Healthy Food & Healthy Living by Dr. Ayala

Is soda bad for your brain?

One of the biggest fears we face – especially if we’re lucky enough to live a long life – is dementia. Despite great efforts to treat Alzheimer's and other dementia forms, there is no cure for this malady. Prevention is crucial.

Important modifiable risk factors for dementia are poor nutrition, binge drinking, lack of physical activity and mental stimulation and smoking.

A new study in the American Journal of Clinical Nutrition looks at a large population of almost 180,000 people in England, with no signs of dementia at the start of the study, and follows them for an average of almost 10 years. The diet of the participants was reported, and their sugary drink consumption tallied. The genetic risk of dementia was assessed for each participant looking at common genetic variants related to the risk of Alzheimer’s disease. 

During follow-up almost 1300 of the participants developed dementia. After adjusting for socioeconomic status, lifestyle factors, such as alcohol intake, smoking, exercise and weight status, and underlying health conditions that may affect dementia risk, the researchers found that those who consumed more than 2 sugary drinks a day had greater odds of developing dementia: their risk rose by some 35 percent. Excessive intake of added sugar was also linked with dementia risk.

The added risk was seen with sugary drinks, but also with artificially sweetened ones. On the other hand, those consuming moderate amounts of fruit juices did not have a higher risk of dementia. These links were not modified by genetic predisposition.

A similar study of almost 3000 people over the age of 60 years showed almost doubling of dementia risk among those with high intake of artificially sweetened drinks, and another study of 1865 people showed greatly increased risk of dementia with an intake of on average 7 sugary drinks a week.

How could sugary drinks impair the brain? It might be that the excessive sugar and rapid rise in insulin impair the brian, and for artificially sweetened drinks the authors suggest that aspartame could disrupt energy production and increase oxidative stress.

Why are sugary drinks singled out?

The western diet contains plenty of added sugar, but while sugar’s added to many foods, most of the added sugar hides in drinks – soda, sports drinks, energy drinks, flavored milks and fruit juices – the sheer amount of sugar in sugary drinks can explain why they are linked so tightly with obesity.

But studies show that there is something distinctive about getting calories in liquid form. Solid sugars suppress hunger somewhat, while liquid sugar – in sugary drinks – doesn’t affect satiety.  Sugary drinks’ calories are just added, and the meals eaten with them will be just as large, if not larger. And several studies have suggested that sugary drinks are an independent risk factor for diabetes and hypertension irrespective of obesity. 

Liquid sugar lends itself to overconsumption, and it might very well be that sugar in liquid form poses an especially tough burden on our body’s metabolism and on our brain’s function.

Dr. Ayala 

Can your diet affect skin appearance and aging?

Healthier diets are associated with fewer face wrinkles, while a diet rich in junk food and meat with earlier skin aging according to population studies. Yes, this is just a link. It might be that healthy eaters avoid the sun and protect their skin from it – excessive sun exposure ages the skin. Health conscious people also tend to avoid smoking, another known skin-aging factor.

Does food affect facial wrinkles?

A pilot study conducted at the UC Davis Dermatology Clinic that actually tests the effects of foods in a controlled setting does so with almonds. Participants (28 postmenopausal women with fair skin that tends to burn and freckle in the sun) were treated with 2 ounces of almonds daily for 16 weeks, and skin assessment was done using high resolution photos, and a computer based validated facial modeling measurement.

The almond group had decreased wrinkles after 16 weeks.

This prospective randomized pilot study was extended and expanded to 24 weeks. This time about 50 women completed the study.

The second study showed that at 24 weeks there was continued reduction of observed wrinkles, there was also reduced pigment intensity in the almond group, compared to the control (pigmentation is another sign of skin aging).

What is it in almonds that can affect the skin? Almonds are rich in vitamin E, an antioxidant that protects from ultraviolet rays that age the skin (UVA). Many nutrients affect skin health: antioxidants and carotenoids such as beta carotene prevent collagen degradation, and provide protection from ultraviolet radiation on the cellular level.

And although this study was performed with almonds, there’s likely nothing unique about these nuts: many healthy foods contain beneficial antioxidants that may reduce wrinkles and improve skin’s appearance. 

A prospective study feeding women 85 grams (~3 ounces) of mango daily for 16 weeks showed a reduction in wrinkling when assessed by photographs. Interestingly, consuming 250 grams (~9 ounces) of mango daily increased wrinkles after 16 weeks. The researches suggest that this unexpected result may be due to the high sugar intake associated with eating high amounts of mango.

Eat well for rosy, clear skin

A skin change that’s clearly connected with food is its pigmentation. 

Skin’s pigment changes after sun exposure: most of us tan when exposed to the sun, by the production of melanin. Skin’s color also changes by the pigments we ingest, mainly due to carotenoids found in carrots, sweet potatoes, dark green leafy greens, sweet red peppers and other colorful fruits and veggies. 

The skin tone associated with eating a carotene-rich diet is deemed more attractive and vibrant in experimental studies.

A study following 35 students for 6 weeks looked at how fruit and veggie intake affects skin tone, as measured by a spectrophotometer. The researchers found that measured skin tone correlated with reported changes in the diet: eating more fruits and veggies increased skin redness and yellowness, and these skin tone changes were achieved with about 4 servings of fruits and veggies.

What we eat, unsurprisingly, affects our wellbeing, and several skin disorders can also benefit from improving the diet. Take acne, one of the most common skin complaints, with 80-90 percent of US teens with some degree of acne. Recent research connects the Western diet – high in processed foods, sugars and animal products, low in plant and whole foods – with acne prevalence and severity.

There are countless reasons to eat more fruits, vegetables and nuts, but if you need yet another compelling one: Good food may give you beauty from within, and is probably at least as effective as some of the expensive creams in the market that promise to do so.

Dr. Ayala

Does when and how you exercise affect your appetite?

Exercise is a cornerstone of wellness, and is independently important. Exercise is also used as a tool to control weight, but it isn’t a very effective weight loss plan when applied without a weight-loss diet. Exercise’s less than expected influence on weight loss is attributed to our body’s tendency to compensate for energy loss by increasing appetite and intake, or energy conservation and a reduction in energy expenditure. But although exercise by itself (without calorie control) doesn’t result in significant weight loss, regular exercise is linked with lower risk of gaining weight over the years. 

Does when you exercise matter?

Does the timing of exercise matter? The study of our circadian rhythm – our internal clocks that run a ~24 hour cycle related to the sun’s activity – is showing that many of our processes, including hormonal secretion, appetite, and metabolic pathways, fluctuate with the time of day. 

A new study in the current issue of the journal Appetite looks at the effect of morning vs. evening exercise on appetite, food intake and voluntary performance.

The healthy volunteers undertook two trials, in one they exercised at 10:30 am, and in the other at 10:30 pm. They ate a standardized meal 2 hours before exercise (intense cycling), and were offered a meal after exercise in which they could eat as much as they wished.

And the results: Although the participants reported similar appetite regardless of the time of day they exercised, they ate on average 150 calories more when they exercised in the evening.

This is a small study, and bear in mind that many people, especially in the US and in Europe, tend to eat more food in the evening as it is. Also, when to exercise isn’t necessarily a choice – time constraints arise throughout the day, and it’s hard enough to fit exercise as it is.

If you do have the flexibility you can experiment with timing your exercise and seeing if it helps you better control your appetite and intake. 

High or low intensity

Another method that could supposedly help with appetite control through exercise is increasing the intensity of the workout. High intensity exercise may suppress hunger more than low intensity exercise.

High intensity interval training – short intermissions of high effort sprints, interspersed with recovery periods – is rising in popularity and is sold as a time-saving and more efficient way to train than moderate intensity continuous exercise.

A new review study in Appetite collected 13 randomized controlled studies compares high and medium intensity exercise.

The researchers found that both types of exercise suppressed appetite for a period of about ½- 1½  hours, high intensity exercise to a greater extent. Which makes sense: during times of acute exercise the body diverts its resources to muscles, and puts the digestive system on hold. We also know that appetite hormones like ghrelin are suppressed during exercise.

The diminished appetite does not last however. Hunger bounces back and the post-exercise disinterest in food is short lived, regardless of exercise intensity.

The habit you can keep

The most important thing is to exercise – time and type of exercise matter less – and even if there’s no effect on weight whatsoever.

The best exercise is the one you can do, the activity that you enjoy, that’s accessible to you, that fits your schedule, that doesn’t cause you discomfort, the one that doesn’t require equipment you don’t readily have or an ill-afforded membership. 

If you still haven’t mastered an exercise habit the most important parameter is sustainability – pick a plan that you could keep and adopt as second nature, one that you can stick to.

To an active and healthy 2023!

Dr. Ayala

Holiday spices add more than just lovely aromas

The aroma of warm spices signals the holiday season: Imagine cinnamon, cloves, nutmeg, cardamom, and black pepper and you can almost sense holiday pies, hot cider, and cozy evenings with loved ones around a fireplace.

The holiday season’s aromatic traditions are a reminder of the importance of spices and herbs. They elevate foods’ flavor into the extraordinary with rich, complex flavors, they bring faraway worlds and memories to the table. 

They can also play an important part in wellness. 

Hippocrates, the father of medicine, supposedly said: “Let thy food be thy medicine and thy medicine be thy food,” and prescribed spices and herbs collected in the Greek hills for healing. A spiced wine recipe containing cinnamon, cloves, allspice and honey is attributed to Hippocrates, and was advocated for many ailments – from the aches of the heart to those of the body. 

We now of course have more powerful and more targeted medications, but for some everyday conditions, and for prevention, science is providing evidence of the benefits of herbs and spices. Spices have antioxidant and anti-inflammatory properties, have been shown to affect fat metabolism, and have been found to aid in several conditions (ginger for nausea, cinnamon for glucose control, curcumin for slowing tumor growth).

Spices and herbs contain many phenolic and terpene compounds, and are an antioxidant powerhouse.

Herbs, spices and the microbiome

One of the ways in which these foods affect health might be by feeding the microbes that live within us – they may help propagate the right kinds of microbes, and these microbes may break down the nutrients within herbs and spices into beneficial metabolites.

And a new study from Penn State University finds that even in the context of an average American diet, adding herbs and spices improves the gut microbiome.

The study, published in the Journal of Nutrition, gave 52 adults at risk of heart disease 3 different doses of a combination of herbs and spices, ranging from ⅛, to ¾ to 1½ teaspoons a day for 4 weeks for each dose. 

Adding herbs to the diet resulted in greater diversity of gut microbes, especially after consuming the medium and higher dose of herbs and spices. 

The authors conclude that: “This study suggests that incorporation of culinary doses of herbs and spices into an average American diet changes gut bacterial composition in adults at risk for CVD (cardiovascular disease). Further investigation of the metabolic implications of these bacterial changes is needed.”

The anti-inflammatory benefits

Another controlled study from Penn State University, looks at spices’ effect on inflammation.

The study tested twelve men who were overweight or obese, and who had at least one risk factor for heart disease, with three versions of 1000 calorie meals. One had no added spices, one had 2 grams of a spice mix (containing basil, bay leaf, black pepper, cinnamon, coriander, cumin, ginger, oregano, parsley, red pepper, rosemary, thyme, and turmeric) and the third meal had 6 grams, amounting to 1-2 teaspoons, of the blend. Blood was drawn before the meal, and hourly in the 4 hours after it, and was tested for inflammatory cytokines (cytokines mediate our immune reactions, recruiting inflammatory cells, stimulating the movement of cells towards sites of inflammation, and changing the behavior of blood vessels).White blood cells were also cultured and stimulated to respond to an inflammatory stimulus, resembling what could happen if the body’s attacked by a pathogen such as a virus.

And the results: Inflammatory cytokines were significantly reduced when 6 grams of herbs and spices are added to a meal.

The antioxidant and anti-inflammatory activities of spices and herbs have been shown in other studies: A study of turmeric in people with obesity showed a reduction in cytokines IL-1β and IL-4, and ginger was shown to reduce circulating inflammatory markers in people with type 2 diabetes.

Healthy foods, and especially plant based whole foods, supply us with a whole array of nutrients that may help support health. Food, however, is much more than fuel for running our systems. Food is what connects us to nature, tradition, family, it brings joy! Wishing you a happy holiday season filled with tasty, aromatic, companionable food. 

Dr. Ayala

Is honey really better than sugar?

We’re encouraged to limit sugar and sweeteners in our diet. The American Heart Association advises no more than 6 teaspoons a day for women, 9 for men, and for added sugar to provide no more than 5-10 percent of daily calories. Excess added sugar is linked with obesity, and many chronic diseases such as type 2 diabetes, metabolic syndrome and heart disease.

And since we like sweet food –  to prefer sweet foods is to be human – are there healthier ways to sweeten food? Are honey, maple syrup, agave and date syrup any better?

Sugar is sugar?

Honey is made by honeybees from the nectar of flowers, and contains, besides sugars, a whole array of organic acids, enzymes, proteins, amino acids, minerals, vitamins, and bioactive substances. It has been shown that honey has beneficial effects on sugar control, weight maintenance, inflammation, lipid profile, and as a common cold remedy.

A new systematic review published in Nutrition Reviews including 18 controlled clinical trials set to examine honey’s health effects.

It found that a median dose of 40 grams (about 2 tablespoons) daily over 8 weeks reduced blood fasting sugar, cholesterol, and triglycerides levels. Raw honey was more effective than honey that was heat treated – most of the benefits demonstrated are from studies that use raw honey.

This review is in line with animal studies: several studies in rats show that regular honey intake results in better sugar control and lipid profiles.

Honey’s wellness benefits are plausible: Honey is 80 percent sugar, mostly fructose and glucose, but there are also “rare sugars” in honey, those include monosaccharides and their derivatives (such as isomaltulose), which have effects on fats on gut microbes. Honey contains phenolic compounds and flavonoids and other important antioxidants. Raw honey contains probiotic beneficial bacteria that are known to regulate the immune system and improve lipid profiles.

The flower source of the honey also matters – clover honey, and robinia honey were especially beneficial for fasting blood sugar control and cholesterol reduction.

Swapping sugar with honey

Honey is still in the “added sugar” category, and as such, should be enjoyed in moderation. Replacing sugar with honey can help with moderation, as you’ll be skipping most processed foods – which are made with refined sugar and high fructose corn syrup. Honey’s price point and nuisance value can help limit your consumption.

A “no refined added sugar” principal that allows for natural sweeteners can make sense if it helps you keep a lid on your sweet tooth. 

The added nutrients in honey can also add a bit of wellness.

The authors of the study also suggest that honey should not be lumped with the other refined added sugars which provide nothing but energy (empty calories): “as honey, when taken in moderation, may offer a variety of benefits for glycemic control and lipid levels.”

The key is moderation. I do believe that sweets and dessert have a place in a healthy diet. But a cake doesn't become “health food” because it’s sweetened by honey – cake is still cake.

Dr. Ayala

The healing power of gratitude

Practicing gratitude is one of the keys to a positive outlook on life. Positivity may come naturally to some people, or during certain periods of your life, but for the rest it requires practice, habit building, strengthening it like a muscle – because our mind naturally gravitates towards worry and the detection of danger and misfortune. A positive attitude doesn’t sugar coat or deny the many challenges around us – it just reminds us that there’s also so much that’s going well and that there's plenty that's good in our lives.

There’s a large body of evidence showing that positivity enhances mental and physical well being. Thankfulness predicts lower rates of depression, better emotional states, and healthier relationships. 

A review in the Journal of Positive Psychology focuses on interventional studies rather than observational ones – a better way to test the effectiveness of a treatment modality. These studies test gratitude practice in a test group, and compare the outcomes with a control group that did not use a gratitude intervention. Interventions included gratitude journaling (writing regularly about what you’re grateful for), writing a gratitude letter (devised by Martin Seligman – the father of Positive Psychology – constitutes writing and delivering a letter of gratitude to someone previously not properly thanked) and the Three Good Things exercise, in which you writing down three good things that happened within a stated time period.

The review includes 25 experimental articles that tested gratitude interventions and psychological wellbeing symptoms, such as depression, anxiety, stress, negative emotions and aggression and finds some evidence that gratitude may contribute to improvement in psychological well being.

There were 32 interventional studies centered on emotional wellbeing: happiness, life satisfaction, quality of life, flourishing, etc. and the vast majority of studies show that gratitude practices increased emotional wellbeing.

Regarding social wellbeing, consisting of social skills, contacts and relationships, and purposeful employment, the review includes 19 experimental studies: Practicing gratitude helps maintain healthy relationships and the formation of new ones.

The mind and the body are one and the same, so mental wellbeing likely affects many aspects of what we call physical health. There are, however, only a few studies focused on gratitude and physical health, but there’s some indication that gratitude lessens stress, lessens self reported symptoms, may lower blood pressure, cholesterol and inflammatory markers, and improves sleep. 

Gratitude – for the small things in life

Paying attention to the smaller things to be grateful for is central to the practice of gratitude. The bigger gifts of life are eminent and require less practice. It’s the small stuff though, that lightens your heart repeatedly once you notice it.

Food is a useful, yet fraught, way to recognize our good fortune. Many of us are troubled by food, and have an ongoing stressful fight with it, labeling some of it, or some of its macro nutrients as bad and even evil. But food should really be our constant reminder of how lucky we are for the bounties of nature, for the nourishment that comes from the sun and the earth and from the labor of all who participate in the vast network that makes our every coffee cup, slice of bread, and every morsel of food.

As is nature. There’s a sunrise and a sunset every day for you to admire, a flower, a bird, a colorful leaf, and an old tall tree. Gratitude to nature not only improves wellbeing, it may also help us to better protect our environment.

Wishing you a happy Thanksgiving holiday, and grateful for your readership.

Dr. Ayala

Why is the world getting fatter (and what we can do about it)

Barbara Corkey, PhD, has been the editor in chief of the journal Obesity for the past 20 years, so you can trust that she’s immersed in research of the causes, consequences and treatment of obesity. 

In these 20 years obesity rates in the US increased from 30 to 42 percent, and the rates of extreme obesity doubled (rising from 4.7 to 9.2 percent). Diseases for which obesity is a risk factor – such as type 2 diabetes, heart disease, stroke and some cancers – are correlated with the severity and duration of diabetes, therefore the appearance of obesity at younger and younger ages suggest a tsunami of these chronic diseases.

Corkey writes, in a recent editorial, that we humans “have developed a method to feed the billions of people on the planet, by developing processing of food with preservatives and other chemicals that can make food last longer and make it cheaper to increase calorie density in small packages.”

The cause of obesity, according to the editorial, is the foods that we make, and society overfeeding on them. 

The most consumed foods in the US are highly processed foods, topping the list are things like grain-based desserts (cakes, cookies, donuts, granola bars), chicken dishes, soda and other sugary drinks, pizza, alcoholic beverages, pasta, and beef dishes. Notably missing are fruits and vegetables and whole, unprocessed foods.

We’re now fighting for our health in a world that we humans have changed.

Surgery, drugs and the promise of culinary medicine

What does medicine offer to treat obesity? Key developments, according to Corkey, include bariatric surgery, which according to a recent study in the New England Journal of Medicine increases life expectancy by 3 years compared to the control group – but it's still 5.5 years shorter than the general population's. As to medications, there’s hope: “Novel drug combinations are beginning to close the gap with bariatric surgery and they appear to be very powerful new tools to treat obesity as a disease.”

The great hope, however: Culinary medicine. This is a new evidence based field, that combines nutrition and cooking know-how, in order to help people prevent disease and maintain health by promoting good eating habits. Culinary medicine has been added to the curricula of more than 55 medical schools, residency programs and nursing schools. The advantage of these kinds of interventions is that they can – and should – be started early, really early, before obesity sets in, and not just when illness manifests itself, and that there are no negative side effects.

Health meets food

Turning to your doctor to address obesity and diet-related afflictions is of course just one of the options at hand. 

Physicians used to get only rudimentary nutrition education as part of their training, and if they do have culinary skills it’s due to personal interests and pursuits, and not their medical education or the hospital lifestyle. Culinary skills can be gained in any number of ways: from friends and relatives, from videos and TV, from books and websites. The only way to get food that’s inexpensive, and that’s healthy for humans and for the planet is by getting cooking and preparing meals.

Much like in dentistry, where a visit with the clinician includes guidance on how to brush, floss, and strengthen your teeth, the visit with health professionals should include wellness counseling, especially nutrition education.

And cooking can also provide comfort and lots of joy. There are too many barriers to simple home food preparation, but to reverse the trend we're on, we'll have to overcome those.

Dr. Ayala

The latest on eating late at night

Late night eating is associated with weight gain and overeating.

Much of it can be sensibly explained: If your workday begins around 9am, to get enough sleep you’ll likely need to be in bed before midnight, and sleep is a foundation of good health and weight maintenance. Also, very few people chop a salad late in the day – midnight snacks tend to be calorie bombs. 

But there might be more to meal timing than the clustering of less healthy behaviors related to late meals. We have internal clocks in every cell in our body, and those relate to the time of day and the setting of the sun. Eating at certain times might actually affect metabolism and appetite.

A new study in Cell Metabolism goes further into understanding if midnight meals, in and of themselves, increase the risk of gaining weight. In order to do that the researchers, led by Nina Vujovic, kept everything – calorie and composition of meals, light exposure, exercise, sleep schedule etc. – constant. The 16 study participants, who were all overweight or obese, each completed two routines in a laboratory setting, the only difference between the two was that the meal was 250 minutes (~4 hours) later.

The hunger effect

Hunger was assessed by participants’ responses to questions such as how hungry are you right now, how much could you eat right now, and others assessing specific desire to eat starchy, meaty, salty, dairy or veggie foods. Late eating caused increased feelings of hunger.

The researchers measured the appetite regulating hormones leptin (promotes satiety) and ghrelin (promotes hunger). Leptin was decreased in the late eating condition, compared to the early-meal one. 

The metabolic effect

To test how meal timing affects the body’s physiology, the researchers measured body temperature, energy expenditure, and also took blood samples as well as biopsies of fat tissue.

When the participants ate later they burned fewer calories, and the fat cell biopsies showed a tendency to store fat rather than to break it down for energy needs. Late eating caused physiologic and molecular conditions favoring a positive energy balance and weight gain. 

Not just a correlation?

The authors conclude: “Our results show that late eating consistently altered physiological functions and biological processes involved in regulation of energy intake, expenditure, and storage — each of these three in a direction favoring weight gain.”

This small study shows that late eating, by itself, while eating the exact same meal, may tip the scale towards gaining weight. 

In reality, people will likely act on the greater hunger experienced with late meals if they have access to food, which most of us do. 

In reality, this physiologic effect is compounded by behaviors that make late-night eating prone to caloric indiscretion. Chances are that late at night you’d rather order pizza and cookies than chop a salad.

Dr. Ayala

Do babies naturally hate Kale?

A new study about kale-hating fetuses captured the imagination in popular media recently. The research, published in Psychological Science, scanned about 100 pregnant women using 4D (3D made into a video) ultrasound after exposing them to vegetables, and showed more smiling fetuses after exposure to carrots, and more “cry-faces” after mom-to-be ate kale. The ability to code 4D ultrasounds and visualize the curve direction of the corner of a fetus’ mouth in the third trimester results in stunning images – cuteness factors in to make these findings more shareable, and that’s perhaps why this study made it into the Today show.

These aren’t surprising findings though. 

Many pregnant women say that their fetus reacted to certain foods they ate, perked up soon after they had a dose of their favorite flavor, and also liked the same food as a baby.

These anecdotes are supported by theoretical plausibility and some evidence. We know that a fetus develops taste buds early on in pregnancy, that the nose passages (where the organ of smell resides) are open, and inhale amniotic fluid by the end of the second trimester.  Even though the flavor and aroma receptors are not fully developed, and the fetal brain interpretations of the senses are immature, exposure to the content of the amniotic fluid does occur. We have evidence that flavor molecules, originating from mom’s diet, are present in amniotic fluid. There are also studies that show that exposure to certain flavors in pregnancy increases the chance the baby will like these flavors better once they’re introduced to new foods, in the second half of their first year of life.

As to the babies displeased with mom’s food choice: prenatal exposure may lead to better acceptance of kale later in life, and that’s something on which "future studies need to follow up,” the researchers conclude.

It’s never too early

Humans are innately fond of sweet food. But natural preference is just a starting point, as we’re creatures of instinct, but also of habituation and learning. As with many natural tendencies, a parent’s role is to modulate these in order to form healthy, adaptable behaviors in their kid. And since when it comes to food only 1 in 10 kids eat enough veggies, focusing on acquiring a flavor preference for veggies could be very beneficial.

These smiling and frowning 4D ultrasound babies are a reminder that it’s never too early: Mom’s diet during pregnancy, and if she’s breastfeeding, after birth, exposes the baby to the flavor of veggies from the very beginning, well before they eat their first pureed tomato. 

Food habits are one of these things in which timing really matters, as there’s a window of greatest opportunity to take advantage of. Generally, a baby’s first 20 months are the time they’re most open to new flavors and textures – bear in mind that babies are usually fed nothing but milk until age 6 months. Acceptance of new foods decreases after that, food neophobia (dislike of the unfamiliar) peaks at age 5 years, after which interest in new flavors and textures usually recovers.

Say yes to vegetables

Taking advantage of the high adaptability of the very young makes for a good head start with loving your veggies. 

A review, in Appetite, looked at 46 relevant scientific studies – 25 interventional studies and 21 observational ones – on promoting intake of vegetables in kids under 3 years of age. 

Repeated exposure (for 8-10 repeats) was the focus of 27 studies. All 21 experimental studies find that recurrent exposure increases intake, usually by at least about an ounce a day, and that the younger the baby, the greater the gains in veggie consumption. The 6 observational studies confirm the same trends. Some of these studies had up to 6-month follow up, demonstrating that repeated exposure led to a stable uptick in veggies.

Pay attention to the amount of repeats in these studies: Although there is a chance of success by the third exposure, it usually takes many repeats to change a baby’s mind and by the eighth exposure about 70 percent of babies will like a veggie they previously disliked. The persuasive power of repetition works on a baby the way it works on us – hence the repetitive messages and ads we shown.

And bear in mind that many things we eventually love to eat are an acquired taste – think coffee, cheese that smells like sweaty feet, garlic, hot sauce  and wine.

Exposure to a variety of veggies also seems to increase veggie intake in young kids in the 15 studies examining this strategy. When variety is piled on to repeated exposure the advantages are magnified.

Setting a veggie-loving example also helps. Parents who eat vegetables in the presence of their kids tend to have kids that eat vegetables. Three observational studies in the above review confirm that setting a good example of eating and enjoying vegetables is associated with higher frequency and intake in their young kids. And that makes sense: Most kids eventually eat their parents’ diet.

It’s never too late to fall for veggies. Try to do so yourself if it hasn’t happened to you yet; there’s lots of flavor and beauty to explore in the veggie kingdom. The finest chefs in the world are demonstrating their newly found veggie infatuation through vegetable tasting menus – why, Eleven Madison Park recently retained its 3 Michelin star status after going plant-based. Serve veggies in a positive, calm, fun, no pressure way. It also follows common sense that better-tasting, nicely prepared veggies will be better liked.

Soon enough, your kids may like kale.

Dr. Ayala

Does the microbiome affect diabetes risk?

Type 2 diabetes is a global epidemic and one of the most common conditions impacting people's health. The incidence of this chronic disease and its many consequences is rising, as type 2 diabetes now presents at younger and younger ages. It is estimated that as many as 9.3 percent of the world population had diabetes in 2019, and that by 2030 the rates will surpass 10 percent.

The risk of developing type 2 diabetes is clearly related to obesity and to genetic predisposition. Diet is also a major contributor, but not by the simplistic way people may imagine: People with no sweet tooth at all can also be at increased risk of type 2 diabetes due to poor diets; it’s not just about eating sweets and added sugars. Diabetes is an impairment of sugar metabolism, leading to too much sugar in the bloodstream instead of our cells. Diet and exercise habits affect our body’s sugar metabolism in profound ways, and the fiber and fat that you eat, and how much you move, change how your body deals with glucose, the body’s main fuel, regardless of how much candy and soda you ingest.

Partners in sugar metabolism

But it’s not just the cell's metabolic machinery, pancreatic hormones and the liver that take part in metabolizing our sugars.

Each of us is home to a whole universe of microorganisms: trillions of bacteria, fungi and viruses. Microbial life outnumbers our own cells 9 to 1, and its genetic material outweighs our own 150 to 1. Our inhabitants, our microbiome, we’re finding out, play a role in our immune system, our endocrine system, our propensity for weight gain, our risk of several diseases, our energy levels, our mental state and our mood.  

Do the microbes living in our gut affect how our body deals with sugars and our susceptibility to type 2 diabetes?

A new study in the American Journal of Clinical Nutrition looks at the evidence connecting gut microbes to insulin resistance and glucose intolerance. The researchers identified 45 relevant studies tying specific gut bacteria to sugar metabolism. 

The researchers found that several types, 6 especially, were linked with sugar and insulin metabolism. Some of these bacteria are protective and their presence is associated with lower risk, yet the presence of other bacteria is inversely correlated with diabetes risk. These links seem to be independent of weight status and of diabetes drugs.

One of the mechanisms in which gut bacteria affect health outcomes may be their production of short chain fatty acids. Short chain fatty acids are produced by bacteria when they break down and ferment dietary fiber and resistant starch. 

And indeed, the presence of short chain fatty acids and other metabolites produced by gut bacteria seems to correlate with sugar control, suggesting that short chain fatty acids may be mediating the microbiome’s effect.

Our microbiome probably plays a role in the development of diabetes. But we also, in turn, affect our microbiome to a great extent. A study in Nature finds that just 2 percent of our gut microbiome profile is genetically determined, and the rest is affected by the environment and by lifestyle.

Helping your helpers

The gut microbial community is dynamic, and depends on many factors, including age, medications, genes, exercise,  and especially diet.

Boosting a healthy microbiome doesn’t require any probiotics, nor are any lab tests, supplements or special foods needed. To improve the gut population it’s recommended you eat whole plant foods (including many types of fruit, veggies, legumes, beans, grains etc.,) lots of fiber, embrace variety in your diet, and reduce refined and highly processed foods.

Dr. Ayala

Exercise for the diet resistant

Exercise is a fundamental and super important key to wellness. Physical activity helps prevent diseases, it slows aging, and boosts mental function. It makes you look and feel better. 

But despite what junk and fast food manufacturers suggest in their clever marketing, tying sugary drinks to athletes and the olympic games, exercise will not enable you to burn off all that many extra calories, and on its own – without a reduction on caloric intake – exercise yields less than expected weight loss. 

An exercise deficit issue?

We can’t really outrun the fork and out-exercise a poor diet. 

Obesity isn’t an exercise deficit problem, it’s mostly an overeating and poor diet problem, Americans aren’t that much less active than they were a few decades ago, and exercise alone isn’t a weight loss plan, studies have shown. The calories burnt by exercise are at least partly compensated for, through energy conservation during the rest of the day and by a vigorous appetite and post-workout eating.

Most overweight people who try to lose weight don’t respond to exercise alone that much, but that doesn’t mean that exercise doesn’t help you lose weight. Exercise not only helps burn calories and keep muscle mass during weight loss, it also helps with improving your diet, as people who pursue fitness often find it easier to eat better – exercise often starts and perpetuates a virtuous wellness cycle. 

And now, a new study in eBiomedicine, part of the Lancet, finds that exercise may play a pivotal role in weight loss for a subset of people. For these people, exercise isn’t just a few more “calories out” in the energy balance sheet – exercise actually changes their metabolism.

Most people lose weight when they reduce their caloric intake, but a subset of people lose much less than expected despite adhering to diet programs. The researchers looked at the clinical records of 5000 women, and identified the 20 percentile who were most and least sensitive to diet, based on their weight loss on a 6-week 900 calorie/day supervised diet. They then studied 10 diet-resistant and 10 diet-sensitive obese women among them. These 20 women were put on a closely supervised exercise regimen. Exercise included weight lifting and treadmills, and was done 3 times a week for 6 weeks. The women were followed by weight and body composition measurements, as well as blood and muscle function tests, and muscle composition studies, using a muscle biopsy.

Flawed one size fits all 

The exercise training had minimal effect on the diet-sensitive women, but among the diet resistant women it changed body composition and muscle metabolism – it increased the mitochondrial content and metabolism in their muscle – and enhanced fat loss.

Besides offering hope for the people who find weight loss especially challenging, this study emphasizes that a personalized approach to obesity is warranted. “In cases in which diet-adherent individuals fail to achieve successful weight loss through caloric restriction, exercise may preferentially enhance their weight loss capacity by reprogramming skeletal muscle metabolism to enhance oxidative processes, consistent with our findings in biopsied muscle and derived primary muscle cells,” the authors write. 

Exercise is recommended for every human out there, for fitness’ sake, and definitely for people trying to lose weight. It may play an especially crucial role for a subset of us, whose positive and weight-altering reaction to exercise is uniquely greater, and in which physical activity over-performs.

Dr. Ayala

The rise and rise of tempting flavor and calorie bombs

Obesity rates have doubled in the US over the past three decades, and are now at about 42 percent. This rise follows a dramatic change in our food environment and our eating habits. Over the last few decades food technologists and food manufacturers have increased and popularized food products that are abundant, relatively inexpensive, calorically dense, and are what’s called “highly palatable”.

What’s highly palatable? A winning formula is one that combines sugars, fat and salt in a way that pleases our reward systems, giving us pleasure. The food industry has been busy making highly processed products from low-cost raw ingredients, and formulating them into super pleasing things to eat. They’re so pleasing that it’s hard to stop eating them – and we’re encouraged to never forget an opportunity to snack on them by massive and ever present marketing efforts.

A new study in the journal Public Health Nutrition examines just how much reformulation occurred in the past decades. While other studies focused on the rise in sugar in the American diet, the authors say theirs is the first longitudinal study of the spread of hyper palatable foods.

The researchers looked at the prevalence of hyperpalatable foods in a statistically representative US food system between 1988 and 2018 using three USDA and CDC food databases. Hyperpalatable foods were identified by criteria that look at the content and proportion of sugars, fat and salt in processed foods.

And the results: Hyperpalatable foods rose by 20 percent in three decades. Hyperpalatable foods now make up 70 percent of available foods in the US! The same grain food items were 50 times more likely to be hyperpalatable in 2018 compared to 1988. Foods in categories such as dairy and meats also went through reformulation, making them more exciting to the palate.

The authors suggest that this reformulation may be one key factor contributing to the rise in obesity: “Our findings indicate that the practices introduced to the food companies in the 1980s focused on product reformulation and enhancement may have had ongoing deleterious effects on our food system, contributing to the current obesogenic food environment in the US.”

An interesting finding is that the biggest rise in hyperpalatable foods was in ones with extra fat and salt – these are meal items and savory foods, rather than desserts and sweets. This may represent the expansion in frozen and ready to heat meals.

Resisting temptation

The authors call for public health policies limiting the addition of fat, sugar and salt to processed foods to below the threshold of hyper-palatability. 

Since that’s unlikely to happen anytime soon, the personal health solution is to minimize highly processed foods and prepared meals as much as possible. There’s a reason it’s so hard to stop eating highly processed foods – they’re designed to entice and to leave you wanting more, while at the same time giving you little nourishment. 

In this food environment it’s no wonder vegetables and fruit find it so hard to compete for attention.

Dr. Ayala

Is what’s better for the planet also better for you?

Climate change is a pressing issue, and mitigating it may demand some personal sacrifices. Our food system and dietary choices are linked to climate change because food production contributes about one third of greenhouse gasses worldwide. 

Some diets contribute more greenhouse gasses than others.

Some food patterns pose more chronic disease risk than others.

Are carbon footprint and disease risk aligned?

Production of animal foods emits more greenhouse gasses. Beef production emits 10 times more than chicken, and 20 times as much as growing legumes, nuts and seeds. We also know that diets high in red and processed meat are linked with higher risk of heart disease, cancer and overall earlier death.

There are very few studies about the relationship between diet, environment and health, according to researchers from Tulane University, led by Donald Rose, and some of the data relies on specific populations, such as Seventh-Day Adventists, who are not representative of the general population, as their lifestyle and demographics aren’t just a choice of plant-based diets. The researchers set out to check personal health/planet health relationships in a representative population. The study appears in the journal Public Health Nutrition.

The researchers looked at the diet of almost 13,000 nationally representative Americans aged 18-64 years. Each diet’s greenhouse gas was calculated. The researchers used a well established diet mortality tool called PRIME (the Preventable Risk Integrated ModEl), which estimates the number of lives that can potentially be saved by behavior changes – such as diet, exercise, smoking and alcohol – in a population. They then simulated what would happen if they moved the population from the highest carbon emitting diet to the lowest.

And the results:

Moving from a high to a low emitting diet would result in 24,000 lives saved a year, which is 2 percent less deaths in the US. Most of the lives saved in this simulation would be thanks to a reduction in heart disease deaths.

What would be causing the reduced risk of death on the low carbon diet? The low carbon diet has more plant foods and less beef.

The results of this study concur with another study from the United Kingdom, which simulated a transition to a less-meat diet, and found a reduction in deaths lined up with the reduction in emissions – the more meat is substituted with plants the more lives saved.

The authors conclude: “This provides additional evidence that diets which are environmentally less impactful are also more healthful and suggests that efforts to implement more environmentally sustainable dietary patterns in the USA could also reduce mortality from CVD (cardiovascular disease).”

Another study in the journal Climatic Change estimated how even small changes to the diet affect both greenhouse emissions and health. The researchers looked at the risk of diabetes, colon cancer and heart disease, and in the simulation model, a diet’s red and processed meat content was progressively swapped with legumes, grains, fruits and vegetables. The model did not alter added sugar, dairy, eggs or fish. The healthier diet models reduced the risk of heart disease, colon cancer and type 2 diabetes by 20-45 percent while dropping  greenhouse gas emissions 200-800 kg per person a year – depending on the relative shift to plant-based proteins.

No sacrifice at all?

While the percentage of vegetarians in the American population is in the small single digits, and that's unlikely to change, moving from a high meat diet to a lower meat diet can save many lives and improve personal wellness, while also improving our atmosphere.

Lowering the thermostat in summer, increasing it in winter, and cutting on driving may be a price we will each decide to pay in order to cut greenhouse gasses, but when it comes to food, what’s good for the planet will also do you some good personally. 

And eating more plants can be pleasurable – a plant-centric diet can be absolutely delicious, so culinary considerations need not suffer.

Dr. Ayala

This is how weight is gained

Although people blame vacations, holiday meals and older age, weight is actually gained slowly and steadily over a lifetime. Much like you don‘t notice the slow bodily transformation from teenager to young adult to middle aged, as there’s no clear demarcation, weight stealthily adds up unnoticed – until it is.

More than 40 percent of the adult US population is obese, and since obesity is a risk factor for a multitude of chronic diseases – including stroke, heart disease, diabetes and several cancers – understanding how weight is gained can help mitigate this raging epidemic.

A new study in the Journal of Obesity looks at weight gain over a decade of almost 14,000 statistically representative Americans. The results are concerning.

Over 10 years more than half of the people followed in the study gained 5 percent or more body weight, more than a third gained 10 percent body weight or more, and a fifth added 20 percent.

Weight gain over the decades

The study shows an inverse relationship between age and weight gain. The greatest weight is gained by young people – between 20s and 30s – in which an average of almost 18 pounds of weight is added on.

Between 30s and 40s weight gain averages about 14 pounds. It slows further down to about 10 pounds for the 5th decade of life, and to 5 pounds for the sixth.

This pattern adds up to 47 pounds over four decades.

People usually think that older age and slower metabolism leads to the accurate observational finding that the older the population the greater the obesity incidence. This is not the case according to these findings. 

In fact, people gain the most weight when they’re young, but despite gaining 18 pounds by the mid 30s many young people are not obese – it takes further weight gain to push you into the obese category.

Obesity rises with age because the older you are the more years you have to steadily gain weight, a process that actually starts early on.

Why would weight gain slow down with age? One reason is that the bigger the body, the more energy it needs, so if you gain significant weight in your 20s and 30s, if you continue eating the same amounts you’ll gain less weight in subsequent years. 

Habits over time

We’ll all age with time – it’s inevitable. But we don’t have to get fatter over the decades – that’s avoidable with better eating and exercise habits.

It's mostly eating habits – lifelong habits – that determine weight gain trajectory.

Studies in overfeeding, in which people were fed 1000 excess calories daily for three weeks led to more than 4.5 pounds gained. But the excess weight was lost within 6 weeks after the overfeeding experiment ended. Extend that to 100 days – which is what was done in another study – and weight gain was on average 18 pounds, and although much of the weight was lost when the experiment ended, 3 extra pounds lingered, and the participants continued to gain weight over the years. 

It's what you do day in and day out that matters the most.

It’s wise to take inventory of your eating habits early on (and it's never too late), add highly nutritious healthy foods such as fruits, vegetables and whole grains, and cut out unhealthy, seductive calorie bombs, such as highly processed foods, foods with lots of added sugar, and sugary drinks.

Dr. Ayala

Is our love affair with protein healthy?

Americans are obsessed with protein. Fat and carbs have been vilified – for unjustified reasons for the most part; there’s nothing inherently wrong with these two macronutrients, even though some fats and refined carbs are foods to limit.

Protein on the other hand has gained a health halo, as many people think that eating more of it will build muscle and help them eat less – hence the popularity of protein shakes and powders.

The body requires protein for its upkeep – from 10-35 percent of daily calories should come from protein, or about 0.8 gram of protein per kg of weight. Athletes, children, pregnant and breastfeeding women, and older adults need more protein than the average adult. 

Protein malnutrition plagued the world in the past, and is still an issue in some parts of the world. The American diet, however, has abundant sources of protein from plants (nuts, seeds, legumes, soy, grains etc.) and from animal sources (meat, fish, seafood, cheese, eggs etc.). Pair this abundance with our appetite for protein, which drives people to pack a protein bar and jerky in their bag just in case, and most Americans get twice as much as they need.

Too much of a good thing?

What happens with excessive protein? 

It does not, as some believe, turn into extra muscle. 

If that extra protein replaces other food (perceived as having a macronutrient that’s out of favor, such as carbs), and caloric intake is adequate, you might be missing out on other nutrients that come from foods not as famous for their protein content. Focusing on protein may turn you away from vegetables, many of which also contain protein, among their very many other important micronutrients: 1 cup of broccoli has 3 grams of protein, a third of its dry weight is in fact protein. 

If that extra protein makes you exceed your caloric expenditure, its energy will be stored as fat, and you’ll gain weight. 

Excess protein is metabolized, its extra energy is stored as fat, other components are broken down and excreted. Protein's amino acids break down into nitrogen, which is excreted through the urine mainly as urea.

A high protein diet may put extra strain on the kidneys.  This is especially worrisome if there’s an underlying kidney disorder – which is not uncommon, as up to a third of Americans are at risk of kidney disease due to conditions such as diabetes and hypertension. 

A new study in Frontiers in Ecology and the Environment looks at how our excessive protein intake affects the environment, especially our waterways.

As mentioned above, the more protein you take in, the more nitrogen you excrete. Multiply that by the US population, and this makes for a significant flow of nitrogen to our waterways. Sewage actually makes 15 percent of the total nitrogen flux from land to ocean in North America. The technology that removes most nitrogen from sewage exists, but it’s expensive, and used on only 1 percent of sewage.

This human contribution of nitrogen to rivers, oceans and lakes results in excessive nutrients in the water, which lead to plant material overgrowth, toxic algal blooms, and hypoxic dead zones. It can make water unsafe to drink. “For most healthy individuals, greater protein consumption has negligible positive health benefits but is potentially deleterious to the environment,” the authors write.

The researchers analysis suggests that if Americans ate the recommended protein amounts it would reduce nitrogen losses into waterways by 12 percent. 

If you also take into account the production of our excess protein food – 60 percent of US protein intake is from animal sources – eating the recommended protein allotment will improve environmental stability much further, as the meat industry is a major contributor to greenhouse gasses and nutrient runoff.

Thinking of food as nutrients isn’t serving our health, as protein isn’t in and of itself better than fat or carbs – they’re all necessary, and can come from healthy – or less healthy – sources. Our focus should be on healthy foods and portion control. If, to increase protein intake, you replace a sugary drink with nuts or legumes this is an improvement. But opting for whey and casein protein powders and processed meat instead of whole foods is clearly a nutrition downgrade, regardless of the macronutrients involved. And this protein-overload trend has environmental costs, too.

Dr. Ayala