Healthy Food & Healthy Living by Dr. Ayala

Should you reduce sugar to lower cancer risk?

Among popular beliefs about cancer risk is the one tying it with excess sugar. The depiction in popular media is that of cancer cells growing fast out of control when there’s plenty of sugar to feast on. 

Is there good scientific evidence that sugar increases the risk of cancer, or is this just a myth? 

What’s already beyond doubt is that excess sugar can lead to weight gain. Obesity by itself, and type 2 diabetes, which is a common consequence of obesity, both increase the risk of cancer. But is excess sugar by itself – in the absence of weight gain – risky?

Cancer cells, like any other cell, need energy to grow and multiply. Due to their relative accelerated growth and the lack of oxygen inside a tumor, cancer cells may need even more energy, and sugar is the energy currency in our body. There are indeed treatments that try to starve cells of carbohydrates through diet, or through manipulation of insulin – which is necessary in order to get sugars inside cells. Other mechanisms that can make the sugar-cancer link suspect are the inflammatory and oxidative state caused by high sugar intake and insulin resistance.

So the sugar-cancer connection is plausible. Several past studies however were quite reassuring for those of us with a sweet tooth: A recent review of 37 studies didn’t find evidence of a link.

That’s why leading cancer research institutions such as the World Cancer Research Fund and the American Institute for Cancer Research don’t list sugar as a cancer risk at this point. But they do warn that “consumption of sugar-sweetened drinks is a cause of weight gain, overweight and obesity,” and being overweight or obese increases the risk of many cancers, and that greater glycemic load is a risk factor for endometrial cancer.

Sugar and breast cancer

A new study, however, finds a worrying link.

The study in the American Journal of Clinical Nutrition looks at a large cohort of more than 100,000 people, whose dietary intake was assessed every 6 months. Sugar intake was analyzed for total added sugar, as well as specific sugar types (table sugar, glucose, fructose, lactose etc.) and participants were followed for a median of about 6 years for cancer diagnosis.

And the results: In this large cohort sugar was associated with cancer, especially with breast cancer, even when weight status was accounted for. Total as well as added sugar quantity were associated with increased risk of breast cancer; sugars from fruit, however, were not associated with cancer risk. 

Excess added sugar is a well known risk factor for diabetes, heart disease and fatty liver disease. This study links sugar with cancer, especially to breast cancer, and clearly further proof is needed; but since the recommendation is to limit added sugar to no more than 6 teaspoons for women, 9 teaspoons for men for heart-health reasons, the suspected cancer link just adds further motivation for what’s a difficult task. Very few people manage to stick to the eat-less-sugar recommendations. Sugar is added to many processed foods – from breads to condiments to breakfast cereals – and just one serving of sugary drinks already puts you over the top. Sugar limits are easily exceeded on a highly processed food diet even without the joy of the occasional dessert.

Cutting excess added sugar in your diet is one of the most important steps towards improving overall diet quality and reducing the risk of weight gain and chronic diseases, and the easiest way to achieve that is through reducing the amount of sugar in drinks – sweetened drinks are the major contributor of added sugars in the American diet and the easiest to cut – and limiting highly processed foods.

Dr. Ayala

 

Is alcohol really a double-edged sword?

Many health conscious people believe that drinking in moderation is good for you.

I, like most doctors, was trained on this advice. The Dietary Guidelines for Americans – and for many other nations – used to recommend 1-2 alcoholic beverages a day, stating that “alcohol may have beneficial effects when consumed in moderation.” 

The science has since moved on, as have the nutrition guidelines, but public knowledge has not. The last thing the 2 billion people who enjoy alcohol want to hear is that alcohol’s alleged health benefits stand on shaky legs, and there are too many interested parties that continue to push this belief.

It’s an inconvenient truth, but the time has come to revisit the widely held idea that alcohol promotes health, because better data contradicts it.

Good for your heart?

The makings of wine as a health food are closely associated with the French paradox. Epidemiologic studies in the 1980s reported the paradoxical observation, that French people have lower rates of heart disease, despite their luxurious, butter-heavy diet. A 60 Minutes broadcast on the subject, ending with Morely Safer holding a glass of red wine, suggested that the secret to heart health “may lie in this inviting glass.” Sales of red wine shot up 40 percent the next year, and wine makers quickly adopted the health food halo.

Wine contains antioxidants and resveratrol, and might increase HDL, the good cholesterol. It seems perfectly plausible that it could improve vascular health.

Alas, there probably is no French paradox. Further studies found the paradox to be an illusion, a distortion, a result of inconsistent disease reporting and other factors.

The most persuasive evidence tying moderate drinking with health is the famous J curve, in which studies show that the risk of death declines with low levels of alcohol intake and then rises proportionately with higher levels of drinking. In other words, moderate drinkers have a lower risk than teetotalers.

Better research, however, flattened the J curve. After adjusting for confounders – the most important bias is reverse causality: sick, frail people tend to stop drinking – it looks like the more people drink the greater their risk of all kind mortality. Apparently, the question “do you drink” is very different from “have you ever been drinking.” When you remove recent quitters from the studies the positive effect of moderate drinking greatly diminishes.

What is moderation?

A new study that included 600,000 from 19 countries, published in the Lancet looked at alcohol consumption and the risk of cardiovascular disease, including heart attacks, stroke and heart failure. The study included only people who currently drink, in order to avoid the bias risk posed by including sick people who avoid alcohol for health reasons.

Alcohol was associated higher risk of stroke, heart failure, aortic aneurism and hypertensive disease, the greater the drinking the higher the risk, and there was no threshold at which drinking was safe, or seemed beneficial.

When it came to non-fatal heart attacks, however, moderate alcohol intake slightly lowered the risk.

Alcohol consumption was positively associated with all cause death, with the lowest odds of dying among people who drank about 5 drinks a week or less.

The authors estimate that for men, reducing drinking from the current suggested upper limit of 2 drinks a day, to no more than 5 a week, would add on average 1-2 years of life.

This study reached the same conclusion as better-conducted recent studies, and studies using genetic randomization.

As alluded above, it’s very hard to disentangle people’s lifestyle habits, and if you look at populations of never-drinkers, such as Seventh-day Day Adventists, who do have lower rates of heart disease, you can’t really know if not drinking alcohol improved or worsened their outcomes, as they usually lead a healthier than average lifestyle, and don’t smoke or eat meat. There is, however, a gene variant that is associated with lighter drinking that has been helpful in alcohol research. People who inherit a certain genetic variant of the enzyme that breaks down alcohol tend to drink less because they feel alcohol’s unpleasant side effects – such as nausea, headache and flushing – more readily. This, in effect, randomizes society by genes, and not by socioeconomic influences. 

People with this gene variant drink less, have fewer incidences of binge drinking, and many more of them abstain altogether, but there still was a wide variation in drinking among them, supporting the notion that there are societal influences, and that drinking culture affects drinking behavior – even among people with a genetic predisposition to drink less.

If alcohol in moderation indeed caused better heart health, we’d expect the people with the alcohol dehydrogenase 1B gene variant to show both above average and below average cardiac outcomes, and we’d expect those of them with the very lowest consumption – the abstainers– to have higher rates of heart attacks. 

But that’s not what studies found. Quite the contrary: those with the gene had 10 percent less coronary heart disease, as well as lower blood pressure, lower BMI, and lower ‘bad’ cholesterol levels across the board.

What about the rest of your body?

While the heart benefits of moderate drinking are questioned, the harms to many other organs are well known, and not in debate.

Alcohol is a known carcinogen.

A statement of the American Society of Clinical Oncology declares that alcohol drinking is an established cancer risk factor: “In the United States, it has been estimated that 3.5% of all cancer deaths are attributable to drinking alcohol. Alcohol is causally associated with oropharyngeal and larynx cancer, esophageal cancer, hepatocellular carcinoma, breast cancer, and colon cancer. Even modest use of alcohol mayincrease cancer risk, but the greatest risks are observed with heavy, long-term use.”

Alcohol is a leading cause of liver disease and liver cirrhosis.

Alcohol during pregnancy may harm the fetus and can cause Fetal Alcohol Syndrome.

Alcohol abuse affects more than 6 percent the US population; about 90,000 people die of alcohol related causes each year in the US.

Which brings us back to the question, is alcohol really a double-edged sword? Is alcohol in moderation beneficial?

Assessing risk and benefits

To reduce the risk of heart attacks, you can adopt several proven steps such as eating more vegetables and walking regularly. Not as seductive as a glass of wine, but almost risk free.

Not that I’m suggesting abstaining altogether. Alcohol, and wine especially, are a deeply cultural culinary joy, and I’m definitely not one to suggest that life should be approached with extreme caution and as an exercise of life prolongation.

On the other hand, alcohol is pushed so very hard that it becomes really hard to ignore or say no to it. Alcohol is almost the co-star in so many movies and TV shows, and is depicted as the ultimate way to relax or have fun – Grace in Grace & Frankie and Alicia in The Good Wife seem to sustain on a liquid diet. And why are there pink ribbons and tie-ins with breast cancer charities on alcoholic drinks? – reminder: alcohol is a risk factor for breast cancer, it’s particularly cynical to promote drinking to fight breast cancer.

I also have no idea why alcoholic drinks are one of the only products still exempt from displaying nutrition information. The caloric burden of alcohol might have tipped people who count every slice of bread towards greater moderation – every small glass of wine is about 120 calories.

Driving a car carries risk. Most of us assume that risk, because we want and need to go places. Taking on a calculated risk is fine. Not thinking about the risk might also be a fair enough choice.

But we can no longer pretend that alcohol – even in moderation – is something we should be doing for our health. 

Dr. Ayala

Motivation, tips and tricks to help you keep healthy new year resolutions

It’s week two of the new year, and chances are your resolve to take better care of yourself in the new year might be starting to slip.

Don’t give up, alludes a new study. Your efforts will we well rewarded, and I have a few science-based tips that can help you keep at it.

Healthy lifestyle and cancer risk

Healthy habits are proven to lower risk of heart disease, diabetes and dementia. A new study in Ecancermedicine, a journal from the European Institute of Oncology, set out to quantify how much of a difference these healthy habits have on cancer risk.

The prospective study included about 350,000 40-69 year olds, who were followed for an average of 5 years. The participants were asked about several habits: smoking, alcohol intake, physical activity and diet. Healthy diet scores were based on the number of portions of raw or cooked veggies and fresh or dried fruit consumed daily, 5-a-day put the participants in the “healthy” eating group. Weight and height were also measured for BMI assessment.

The number of healthy lifestyle habits was inversely correlated with cancer risk. Each additional good habit reduced cancer risk by 8 percent. Following all 5 habits -- normal BMI, moderate alcohol consumption (14 units or less per week), regular exercise, eating 5-a-day fruits and veggies, and no smoking -- reduced cancer risk by one third, and delayed the age in which cancer appeared by 6 years!

These findings are quite similar to those of another study following another cohort of almost 400,000 people for 11 years that found that adopting guidelines for diet, nutrition, physical activity, and healthy weight was associated with a 25 percent reduction of the risk of developing most types of cancer.

Ask your doctor about this magic drug

These studies focused just on cancer. The evidence regarding diabetes and heart disease is even more impressive.

If there were a drug that could lower your cancer risk by 25 or 33 percent, wouldn’t you be urging your doctor to prescribe it for you? I bet you would, especially if there were no nasty side effects to warn about, since the treatment is absolutely 100 percent safe.

So let’s make 2018 the year in which you implement at least one more healthy habit.

Tips and tricks to help you keep your wellness resolutions

Connect your resolution to something you already do:

Pick a cue – something you do every day, preferably something you like to do – and make it prompt you to exercise, chop that salad or drink some water. Your favorite show or podcast can be a reminder to do a set of pushups or squats. Brushing your teeth can be attached to practicing mindfulness for a few minutes or to washing fruit to pack in your bag for a healthy snack. Going on lunch break could be a reminder to climb a few sets of stairs on your way back to your desk.

Keep it for 30-60 days:

It takes a while until a habit is established, until it becomes routine and automatic. The first few months are hard, but after a habit is set, it’s programmed in, and carrying on is almost effortless. If your streak has been broken and you’ve skipped a day or two, don’t give up, and patiently start over, reminding yourself that it gets easier with time. Some habits are easier to adopt, some harder, but time’s on your side.

Be kind to yourself:

Adopt an inner voice that treats you as you’d treat your best friend. What would you say to your friend that says they – despite their resolution – didn’t exercise all week? You certainly wouldn’t deride them, would you? You’d tell them that it’s understandable, and that today’s a new day, a new opportunity, right?

Keep at it! 

Dr. Ayala

Coffee and cancer?

You might have been surprised by the news coming out last week, announcing that the World Health Organization (WHO) found that coffee isn’t carcinogenic after all. If I were in the coffee business I’d want this news item to get as little publicity as possible, as I doubt anyone was worried about coffee’s carcinogenicity before they were told not to fret.

So what’s this all about?

The last time the WHO’s International Agency for Research on Cancer (IARC) evaluated coffee was in 1991, and at that time it gave it a “possibly carcinogenic to humans“ classification because of limited evidence associating coffee and bladder cancer in case-control studies (which are not the best evidence).

For this evaluation 23 scientists from 10 countries met in Lyon, France, and evaluated 1000 observational and experimental studies that have accumulated in the meantime.

Overall, cancer risk and coffee seem to be unrelated, they concluded.

The group also evaluated mate, a drink popular in South America and steadily gaining popularity elsewhere. Hot mate was classified as “probably carcinogenic to humans” in 1991 based on limited evidence. The new evaluation, based on the latest knowledge, concludes that while the high temperatures in which some people drink their tea or mate might act as a tumor promoter, the researchers think the mate itself is not a problem. Beware of very hot drinks, they advise:

“Drinking very hot beverages at above 65°C was classified as “probably carcinogenic to humans.”

Should we worry?

The WHO’s findings are a scientific evaluation, not a set of recommendations on what to eat.

The categories used by the IARC can be quite confusing.

The highest, most dangerous category, category 1: Carcinogenic to humans, includes processed meats (bacon, ham, hot dogs, sausages). And also cigarettes. Does this mean that meat is as carcinogenic as smoking tobacco? It definitely doesn’t. More than 85 percent of lung cancers result from tobacco smoking, yet according to the WHO’s report 50 grams (about 2 ounces) of processed meat daily might increase colorectal cancer by 18 percent -- smoking is much more likely to cause cancer than eating processed meat, even though both are in the same category. In this same category 1 you can also find ethanol in alcoholic beverages, secondhand smoking, engine exhaust, air pollution, and sun exposure. The sun’s rays, X rays and gamma radiation are all in the same category 1, but that doesn’t mean that beach vacations are as risky as getting a weekly CT scan.

Now, lets visit the category coffee’s in, it used to be 2B: Possibly carcinogenic to humans, and now it’s group 3: Not classifiable as to its carcinogenicity to humans. Coffee shares this distinguished category with tea.

This is science speak, so the best, most benign score you can get is category 4: Probably not carcinogenic to humans – scientists are very careful, and will never declare certainty.

Once the “can it cause cancer” question is raised to the IARC the best possible outcome can be: Probably not. When you ask a scientist: Is this – pertains to practically anything -- 100 percent safe? the answer can never be a simple: Yes.

A better place to look for practical dietary advice is the Scientific Report of the 2015 Dietary Guidelines Advisory Committee, which concluded:

“Currently, strong evidence shows that consumption of coffee within the moderate range (3 to 5 cups per day or up to 400 mg/d caffeine) is not associated with increased long-term health risks among healthy individuals. In fact, consistent evidence indicates that coffee consumption is associated with reduced risk of type 2 diabetes and cardiovascular disease in healthy adults. Moreover, moderate evidence shows a protective association between coffee/caffeine intake and risk of Parkinson’s disease. Therefore, moderate coffee consumption can be incorporated into a healthy dietary pattern, along with other healthful behaviors…However, it should be noted that coffee as it is normally consumed can contain added calories from cream, milk, and added sugars. Care should be taken to minimize the amount of calories from added sugars and high-fat dairy or dairy substitutes added to coffee.”

I wouldn’t be at all surprised if one day we’ll discover that worrying about cancer may cause cancer.

Dr. Ayala

Meat and cancer: Reason to panic?

The World Health Organization (WHO)’s recent findings, connecting red and processed meat with cancer, reverberated throughout the world, but they’re hardly big news.

The American Cancer Society’s guidelines have been advising for decades to “limit how much processed meat and red meat you eat” and mention that: “many studies have found a link between red meat or processed meat intake and colorectal cancer risk.”

And indeed, the International Agency for Research on Cancer (IARC), the expert group that evaluated the meat-cancer link for the WHO, had at their disposal 800 studies on the topic. These studies have been trickling in over the years -- none of them with encouraging news -- leading many agencies and experts to recommend limiting red and processed meat. The WHO basically reviewed the same set of evidence and came to the same unsurprizing conclusions.

But for years, it seemed that the only people noticing those warnings were vegetarians (of which I am one for full disclosure).

So maybe, the WHO’s report’s language is a bit clearer, a bit stronger.

Maybe the main difference is that the media had a bigger appetite for this report at this time – is it because beef jerky and bacon are such hot trends recently?

Or maybe people are more interested in the connection between food and health nowadays, and finally realize that prevention is easier and more effective than treatment.

What should you do? 

The WHO’s findings are a scientific evaluation, not a set of recommendations on what to eat. So here's my take:

If you eat processed meat and don’t want to give it up, meat is definitely not like cigarettes, as some headlines suggested. Meat’s not as carcinogenic and it has nutritional value – cigarettes, on the other hand, have high risk and absolutely zero health benefits. More than 85 percent of lung cancers result from tobacco smoking, yet according to the WHO’s report 50 grams (less than 2 ounces) of processed meat daily might increase colorectal cancer by 18 percent, so smoking is much more likely to cause cancer than eating processed meat, even though both are in the same category of “carcinogenic to humans.” 

And mind you, the IARC’s notorious list of human carcinogens – to which processed meats was added to – also includes ethanol in alcoholic beverages, some types of human papilloma virus (HPV) that quite a few parents resist vaccination from, secondhand smoking, and sun exposure.

Two substances can be in the category of “carcinogenic to humans”, but that doesn’t mean they’re equally dangerous, because the level of risk and the amount of exposure matter a lot. The sun’s rays, X rays and gamma radiation are all in the same category, but that doesn’t mean that going to the beach every weekend is as risky as getting a weekly CT scan.

On the other hand, if you’re open to reducing meat intake, there are many health, environmental and ethical reasons to do so. The scientific advisory report that provides the scientific basis to the upcoming 2015 Dietary Guidelines for Americans stated that:

“Consistent evidence indicates that, in general, a dietary pattern that is higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts, and seeds, and lower in animal-based foods is more health promoting and is associated with lesser environmental impact”.

This report from the WHO is just one more reminder of the processed and red meat cancer link that’s been known or suspected for quite a while, and just one more reason to lower the very high meat intakes typical of the American diet.

Dr. Ayala

 

A miracle diet that prevents cancer?

If you’re ready to believe the sensational titles and overhype in mass media, miracle super foods that decrease the risk of cancer are discovered every other week.

Except miracles are just that: something that rarely happens, and many of these reported ‘proven’ food cures are based on flimsy findings, never again to be reproduced.

Nevertheless, health experts are unanimous about the effect our diet as a whole has on health, and on cancer risk. The World Health Organization estimates that 25 percent of death burden in developed countries is due to lifestyle – completely up to us – risk factors.

8 healthy habits

In 2007, a collaboration between the World Cancer Research Fund and the American Institute for Cancer Research (WCRF/AICR) evaluated the evidence and produced consensus recommendations for reducing the risk of developing cancer and for promotion of general good health and wellbeing. The WCRF/AICR report is the largest study of its kind, and its conclusions are as definitive as the available evidence allows.

The report featured eight general diet and lifestyle recommendations for cancer prevention:

“1: Body Fatness: Be as Lean as Possible Within the Normal Range of Body Weight.” Maintaining a healthy weight throughout life may be one of the most important ways to protect against cancer, and being overweight or obese increases the risk of some cancers.

“2: Physical Activity: Be Physically Active as Part of Everyday Life.”

“3: Foods and Drinks That Promote Weight Gain: Limit the Consumption of Energy-Dense Foods and Avoid Sugary Drinks.” Sugary drinks were targeted specifically in the report: “Such beverages appear to exert little influence on total daily self-selected energy intakes and their habitual consumption can lead to rapid and sustained weight gain even in the face of restricted solid food intake”. Another recommendation under this heading is “Consume 'fast foods' sparingly, if at all.”

“4: Plant Foods: Eat Mostly Foods of Plant Origin.” Diets that are protective against cancer are characterized by large intake of foods of plant origin and, indeed, several cancers are responsive to increased intakes of plant-based foods.

“5: Animal Foods: Limit the Intake of Red Meat and Avoid Processed Meat.”

“6: Alcoholic Drinks: Limit Alcoholic Drinks.” (Men-to 2/day, women to 1/day).

“7: Preservation, Processing, Preparation: Limit Consumption of Salt and Avoid Moldy Cereal Grains and Pulses (Legumes).” Salt and salt-preserved foods probably contribute to stomach cancer risk, and foods contaminated with aflatoxins are a cause of liver cancer. Although salt is necessary for human health, typical levels of consumption are vastly excessive.

“8: Dietary Supplements: Aim to Meet Nutritional Needs Through Diet Alone.” Dietary supplements are not recommended for cancer prevention. According to the report the greatest danger associated with the use of dietary supplements is the possibility that consumption of supplements is serving as an alternate to good nutrition, and supplements are taken as “magic bullets” to compensate for cancer-friendly dietary and lifestyle practices.

So, not as easy as popping a supplement or drinking acai juice, but does this recipe for cancer reduction and longevity actually work?

Not a shortcut, but it will get you there

A new study in the American Journal of Clinical Nutrition, including almost 400,000 people from 9 European countries, scored participants’ compliance with the 6 first WCRF/AICR recommendations (there was insufficient data to assess recommendations 7 and 8). Women were also assessed for another WCRF/AICR recommendation specific to women: Breastfeeding. The total possible score for a man was therefore 6, and for a woman 7. The group was followed for about 12 years, and during that time almost 24,000 people died, 48 percent of them from cancer.

People with the highest WCRF/AICR score (5-6 for men, 6-7 women) had almost 34 percent lower risk of dying than those that had the lowest scores (0-2 for men, 0-3 for women). Each additional point in the WCRF/AICR score was associated with a 1.2 year increase in life expectancy, and a higher score was associated with lower risk of death from cancer, cardiovascular disease and breathing problems. The recommendations regarding overweight and obesity, and eating plant food, were the most strongly associated with risk of dying.

We like things fast and now, and the WCRF/AICR recommendations aren’t a shortcut, but isn’t it nice to know that we do have some control over our heath trajectory?

Dr. Ayala

The dos and don'ts of colorectal cancer prevention

Cancer of the colon and rectum are the third most common cancer in the world, accounting for 10 percent of cancer overall. Colorectal cancer is correlated with industrialization and is more common in higher income countries. In fact, a rise in its incidence usually coincides with the spread the western diet and lifestyle – Japan, Singapore and Eastern European countries experienced a doubling of colorectal cancer rates in the last few decades – therefore nutrition and lifestyle have always seemed to play a big part in increasing the risk for this often deadly disease.

The World Cancer Research Fund is a non-profit that funds scientific research on cancer prevention and promotes healthy living. A new authoritative report from its Continuous Update Project reviewed the current research papers (hundreds of them), weighed the evidence, and came out with an analysis of what we can all do about reducing our risk of colorectal cancer.

Reducing risk, increasing protection

The expert panel found convincing, consistent and cumulative evidence for several modifiable factors:

Probably protect against colon cancer:

• physical activity

• foods containing dietary fiber – the data is about fiber contained in food naturally, not fiber supplemented to food or in supplements

• garlic, milk, and calcium – evidence not as strong as the factors mentioned above, but still quite convincing

Probably increase risk of colon cancer:

• consumption of red meat and processed meat – this is a dose-response relationship, the more red/processed meat the higher the risk

• alcoholic drinks (by men and probably by women)

• body fatness and abdominal fatness – abundant and consistent evidence that obesity, and especially increased belly fat, are a serious risk factor

For other factors the panel found that the evidence is limited and only suggestive of a cancer causing effect:

Maybe protective foods:

• non-starchy vegetables
• fruits
• foods containing vitamin D

Maybe risky foods:

• Foods containing iron
• cheese
• foods containing animal fats
• foods containing added sugars

A plant based diet for cancer prevention

Although cancer is a disease caused by many factors – genetic predisposition and environmental exposures to name just a few – experts agree that many cases of cancer can be prevented. Scientists estimate that by eating healthy, being physically active and maintaining a healthy weight we can prevent about a third of the most common cancers.

What is healthy eating? This report, like many others points toward a more plant centered diet as the best description of what eating well is at its essence.

There is no compelling evidence to convince even me (full disclosure: I am a lifelong vegetarian) that meat in moderation causes cancer or any other disease, but there’s no doubt that half a pound of meat a day – which is what the average American eats – is way too much.

The highly processed food and fast food diet (which can easily be called the fiber-less diet) is definitely the riskiest way to eat when it comes to colorectal cancer, and it plays a role in numerous other ailments, too.

This weekend marks the official beginning of barbeque season, so how about a few more veggies on that skewer?

Dr. Ayala

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

Can vitamin D protect from cancer?

We’re living in the glory days of Vitamin D, which is now touted as a miracle cure-all treatment for, well, practically everything. Doctors are testing their healthy patient’s vitamin D levels and deficient or not, many choose to pop a vitamin D supplement, just in case.

Every day a new study catches the attention of reporters – if only for a brief moment – who are quick to announce that vitamin D deficiency can be blamed on yet another ill. Judging by some headlines the sun vitamin can cure diabetes, heart disease, cancer, hypertension, depression, obesity and even the common cold.

Scientists are known killjoys, and have been trying to curb the enthusiasm for vitamin D supplementation, noting that most of the vitamin D studies are observational, and that much like other vitamin supplementation disappointments (remember the vitamin E, A and C crazes?) it very well might be that healthy people tend to have higher levels of vitamin D (an explanation of why that’s so later), which does not mean that taking vitamin D will make you healthier. Correlation doesn’t prove cause, experts remind us, and they suggest we await further research.

Last November the Institute of Medicine Committee released its report stating that vitamin D is important for bone health, has not been a proven panacea to any other illness, and that most people have adequate amounts of vitamin D (the committee’s lower limit cutoff is 20 nanograms of vitamin D per milliliter of blood, while many labs shoot for 30).

Vitamin D and cancer

Three of the vitamin D experts who were part of the Institute of Medicine’s committee published a new commentary in the New England Journal of Medicine, elaborating why the panel thinks vitamin D isn’t ready for prime-time in cancer prevention.

The beginnings were promising -- several observational studies showed that lower levels of vitamin D were correlated with cancer. But association studies have important limitations, the authors warn, especially where vitamin D and cancer are related.

Obesity, lack of exercise and poor nutrition are known risk factors for cancer. Those precise risk factors tend to be associated with lower levels of vitamin D – vitamin D is sequestered in body fat, therefore overweight people have lower measured levels of this vitamin, non-exercisers tend to spend less time outdoors absorbing the sun and make less of the vitamin, and people who pay less attention to healthy nutrition may get less vitamin D from food or supplements.

And let’s not forget the reverse causation bias: People who are not in great health will stay indoors, eat poorly, and therefore have lower vitamin D levels.

Randomized trials, in which people are randomly assigned to be treated either with an active ingredient, or with a placebo, are much more reliable than observational or case-control studies. There are very few randomizes clinical trials looking at the effect of supplemental vitamin D on cancer incidence. The results of these have been disappointing, inconsistent and inconclusive and research hasn’t established a cause-effect between vitamin D and cancer as of yet. The receptor for vitamin D is expressed in most of our body; therefore it is possible that this nutrient plays a role in cancer prevention or progression.

Several new trials assessing vitamin D supplementation’s effect on cancer are underway, and we can remain hopeful that their results will support vitamin D's benefit for conditions other than bone health, but at this point the authors conclude that “the existing evidence falls short”.

Practical approach to vitamin D

Vitamin D maintains normal blood levels of calcium and phosphorus, and is critical to forming and maintaining our bones.

Our body makes most of its vitamin D: Our skin produces vitamin D after exposure to ultraviolet light from the sun. Just 10 minutes of sun exposure daily will usually get us enough production to prevent deficiency, and the extra vitamin produced is stored for rainy days. Foods with naturally occurring vitamin D aren’t common, and include fatty fish, eggs and mushrooms. Many other foods are fortified with vitamin D: Milk, flour, cereals and margarine are a few examples.

The new reference vitamin D intakes issued by the Institute of Medicine are 600 IU/day for most people aged 1-70 years (see link for other age groups). People who rarely get sun exposure and dark-skinned individuals should probably take vitamin D supplements. While our body never makes too much vitamin D, even if we’re out in the sun all day, day after day, it is possible to suffer vitamin D toxicity (which can cause kidney stones and tissue damage) when we ingest too many supplements, therefore the upper limit recommended by the Institute of Medicine report is around 2000 IU/day.

Wouldn’t it be nice if we could prevent a myriad of illnesses by a treatment as simple as a vitamin pill? Unfortunately, research has not proven that vitamins cure any condition besides vitamin deficiencies (which are very uncommon in the US), and more is not better when it comes to these essential vitamins. For now, I’d stick with Michael Pollan’s rule #40: “Be the kind of person who takes supplements – then skip the supplements.” Becoming that person isn’t easy – it requires adopting good eating and exercise habits – but popping a vitamin isn’t a shortcut to getting the same health benefits.

Dr. Ayala

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

Obesity: Prevention is the cure

The Emperor of All Maladies by oncologist Siddhartha Mukherjee is a biography of cancer, told as the story of the patients battling the dreaded disease, the doctors who care for them and the researchers laboring in search of a cure. It’s also the fascinating story of cancer itself — a mysterious, ancient, devious, tentacled villain, whose nature we’ve been trying to unravel for centuries. The chronicles of this effort are a window into the thrill and tediousness of medical and scientific research. It is the best book I’ve read in a while and I’d like to share just one thought I had while reading it.

The “war on cancer” was declared 40 years ago. Twenty something years into this war, the incredible effort and funds invested in finding new drug therapies and new treatments yielded a few significant “wins” — childhood leukemia, Hodgkin’s lymphoma and testicular cancer became, quite often, curable diseases. But despite some progress, a snapshot of cancer in the 1980’s showed that more Americans were dying of cancer than ever before.

An 1985 article in Scientific American by Harvard biologist John Cairns quantified the lives saved by cancer treatment at the time and found the number to be quite modest. Cairns wasn’t at all surprised by the humble gains, and suggested no one who knows anything about the history of medicine should be. Treatment alone had never eradicated any disease. Tuberculosis, which was one of the leading causes of death in 19th century America, declined well before the arrival of effective antibiotics against its causative bacteria thanks to better nutrition, sanitation and living conditions. Polio was eradicated in the US through vaccination, which prevented disease. Mukherjee quotes Cairns: “The death rates from malaria, cholera, typhus, tuberculosis, scurvy, pellagra and other scourges of the past have dwindled in the US because humankind has learned how to prevent these diseases…To put most of the effort into treatment is to deny all precedent.”

Obesity treatment doesn’t work

Which brings me to our fight with obesity. The weight-loss industry is a multi-billion business. Books, meal plans, support groups, supplements, specialty foods, drugs to suppress appetite, exercise plans and weight loss surgery are just a partial list of possible treatments. They all have their place, and testimonials of success stories can easily be attached to each treatment modality.

But while treating people for obesity is possible, we are facing an epidemic -- two thirds of our population are overweight or obese -- can we delude ourselves into thinking we can treat the majority of our population?

No human ailment has been defeated by treatment, and obesity is no exception. Thousands of weight loss products and plans, and the numbers won’t budge: We’re getting no thinner.

Prevention is the cure, and most of our effort should be focused on prevention. The problem is that prevention isn’t heroic, sexy or profitable. Saving someone from the abyss garners attention, while avoiding a problem goes unnoticed – there is no story to tell.

But prevention is what we have to do, and in order to do that we need to educate our kids on what, how and how much to eat, improve our food landscape, create living conditions that promote physical activity, and remove the oh-so-many messages and cues that make overeating of all the wrong things the default.

Obesity and cancer

Obesity prevention brings us right back to the war on cancer.
Tobacco is a very potent and widespread carcinogen, responsible for an impressive one-third of cancers. Cancer prevention efforts have to start with fighting tobacco use, yet despite major efforts one in five Americans still smokes.

Obesity is a known risk factor for many major chronic diseases, including heart disease, diabetes and stroke. Obesity is also the most prevalent risk factor for many cancers -- breast, endometrial (the lining of the womb), colon, kidney, and esophageal cancer are all associated with excess weight.

Prevention is the only way to cure an entire society. It’s the economical way to do it, too. Obesity treatment has proven to be one of the toughest problems to solve, even at the individual level (so very few dieters manage to maintain their new thinner weight). In the case of obesity, the diet wars have been a distraction from the fact that most diets fail. Prevention, starting at a very young age, is our only chance to reduce our levels of obesity and disease as a society.

Dr. Ayala

"If people are constantly falling off a cliff, you could place ambulances under the cliff or build a fence on the top of the cliff. We are placing all too many ambulances under the cliff." — Denis Burkitt

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

Another apple-a-day may save more lives than the Toyota recall

Many health organizations, including the World Health Organization and the National Cancer Institute, recommend five servings of fruit and vegetables daily to help ward off disease.

Some people (I’m not one of them) go even further and propose that eating enough fruits and vegetables provides strong protection from cancer.

Cancer is a complex group of diseases. We still know very little about what causes some cancers, but it’s probably safe to say that increased risk for most cancer types usually stems from a combination of factors—some genetic and environmental, which are hard to control, and some that we have much more power over. Smoking, exercise, obesity, diet and sun exposure have all been shown to affect cancer risk.

A healthy lifestyle has many components, and I personally don’t believe any one healthy diet habit by itself—even if practiced religiously over a lifetime—has a hugely dramatic effect on cancer incidence in a population.

Having said that, every little bit helps, and while we shouldn’t exaggerate any intervention as the “solution” to cancer, these small measures together do add up and help prevent some disease.

That, by the way, is why I see all health claims on food as at least a little misleading. The diet-health relationship is real, but is always more complicated and variable than what a simplistic statement implies.

A new study in the Journal of the National Cancer Institute got quite a lot of coverage in the past few days; it found what the authors called only a weak association between high fruit and vegetable intake and reduced overall cancer risk. The headlines in many news publications (“Eating Vegetables Doesn’t Stop Cancer " in the New York Times, “Fruit and vegetables have little effect on cancer risk, study finds ” in The Guardian) suggested deep disappointment over fruits and veggies’ “poor performance” against cancer.

Is this a blow to the five-servings-a-day advice? Let’s first take a closer look at the study.

Paolo Boffetta of the Mount Sinai School of Medicine in New York and colleagues analyzed data from the EPIC study (European Prospective Investigation into Cancer and Nutrition), which included almost 500,000 participants from ten Western European countries. In about nine years of follow-up, more than 30,000 participants were diagnosed with cancer.

The authors found a small but statistically significant association between high intake of fruits and vegetables and reduced overall cancer risk--the higher the intake the lower the risk.

The data shows a 3 percent lower risk of cancer for every 200 grams, or seven ounces, of fruits and vegetables a day a person eats. People who ate five or more servings a day had 11 percent fewer cancers than those who ate 0-1.5 servings a day.

These results were consistent across the countries studied.

Higher intakes of fruits and vegetables in this study group were associated with other healthy behaviors, such as smoking avoidance, limited alcohol consumption and exercise, which may also be protective from cancer. But the small protective effect of fruits and veggies persisted even after adjusting for these factors.

How significant is 3 percent protection from cancer?

Numbers are often hard to understand without context—they aren’t as absolute as they sound. Is 3 percent a small number?

There is of course no one right answer to that.

Let’s take a look at the Toyota recall and compare risk/benefit ratios.

The chance of an owner of a recalled Toyota experiencing a deadly acceleration problem is assessed at 2.8 in a million. (There were 17 fatal accidents related to acceleration in 10 years, before six million cars were recalled. New complaints are now pouring in, which is quite typical after a recall and law suits are announced.) But we all expect Toyota to recall and fix all relevant cars, and we’re angry they failed to address this problem sooner.

The yearly cancer incidence in the U.S. is estimated at 4,600 in a million; one and a half million Americans are diagnosed with cancer each year, and 1,500 die of cancer daily. If, as this study suggests, eating an additional seven ounces a day of fruits and veggies can reduce cancer incidence by 3 percent we’d have 40,000 fewer Americans receiving the diagnosis of invasive cancer yearly.

In Toyota's case we demand action when the current risk is as small as 2.8 in a million, yet with cancer, where the disease risk is as high as 4,600 in a million, some suggest that a reduction of 3 percent in risk does not make much of a difference.

I wouldn’t perhaps recommend a drug with many side effects if it reduced a rare disease’s risk by 3 percent, but for an “intervention” as benign as eating an additional apple a day, and a disease as serious and common as cancer a 3 percent risk reduction looks like a decent size reward.

What if fruits and veggies offer no protection from cancer?

When a study shows only a small difference in outcome between the studied groups, there’s also the possibility that this difference can be explained by chance, and by something other than the variable studied. In this case we have to bear in mind that eating more fruits and veggies is generally associated with a healthier lifestyle, and no matter how hard the authors try to control for the other healthy lifestyle factors, some bias may remain.

So even though this study and several others show a probable small reduction in all-cancer risk, let’s bear in mind that it’s also possible that eating your veggies might offer no significant protection from cancer.

Yet, this “worst case” scenario still leaves us with many excellent reasons to continue promoting fruits and veggies. Here’s a partial list of good reasons to eat plenty of fruits and vegetables:

• They help lower the risk of heart disease and stroke (a study showed a 30 percent lower risk in people eating five servings a day, compared to those who eat only 1.5 servings a day)

• They help lower blood pressure

• They help lower diabetes risk

• They help lower risk of eye (cataract and macular degeneration) and digestive (constipation and diverticulitis) problems

• They provide lots of fiber, both soluble fiber, which helps lower cholesterol and regulate sugar, and insoluble fiber, which is important to digestive health

• They provide vitamins, minerals and many other beneficial plant molecules—phytonutrients—many of which we’re only starting to understand. (And I’m sure there are a few we have yet to discover. My mom knew nothing about lycopene, for example, when she fed me tomatoes and watermelon.)

• They have high nutritional value and low caloric density, so eating many fruits and vegetables (rather than practically any other food) helps lower caloric intake and maintain optimal weight

• They taste good, are beautiful to look at, and connect us to nature

My last item on the virtues list is completely non-objective; I’m guilty of total fascination with colorful growing things that we can also eat.

If, in all the years that fruits and vegetables have been consumed and studied, the worst we can say about them is that they’re not as thick a shield against all cancers as some had hoped, this speaks to just how good for us they really are.

So keep those fruits and veggies coming!

Dr. Ayala

Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!

This entry has been posted as part of The Kathleen Show's Prevention not Prescriptions

Body mass and cancer

I am taking a short break for a few weeks to spend time with my family and travel. Meantime, I'm reposting some of the more popular posts I’ve written over the past year so that new readers have a chance to catch up. Enjoy this post! - Ayala

Most people think changing their diet would make them healthier, and they are right. Nutrition affects health in a profound way, and unhealthy eating habits are a big risk factor in many diseases.

Excess bodyweight (overweight or obesity) is increasingly recognized as an important risk factor for some cancers. Since two thirds of Americans are overweight or obese, overeating is a major contributor to cancer occurrence in the US, even more so than cigarette smoking.

Last week, a new study in the prestigious Lancet, showed further evidence that increased Body Mass Index (or BMI, a measure of body fat based on height and weight that applies to both adult men and women) is associated with increased risk of common and less common malignancies (The Lancet, Volume 371, Issue 9612, 16 February 2008-22 February 2008, Pages 569-578). The researchers found that in men, a 5kg/m2 increase in BMI raised the risk of esophageal adenocarcinoma by 52%, thyroid cancer by 33%, and colon and kidney cancers each by 24%.

In women, a BMI increase of 5kg/m2 increased the risk of endometrial (59%), gallbladder (59%), esophageal adenocarcinoma (51%) and kidney (34%) cancers.

They also noted weaker but significant positive associations between increased BMI and rectal cancer and malignant melanoma in men; postmenopausal breast, pancreatic, thyroid, and colon cancers in women; and leukemia, multiple myeloma, and non-Hodgkin's lymphoma in both sexes.

This study is a meta-analysis combining findings of 141 carefully selected previous studies, and looking at over 282,137 cases of cancer.

It offers further support to the link between obesity and cancer, but does not supply a clear mechanism for how extra weight causes the disease.

Evidence has been accumulating about the relationship between lifestyle, nutrition and cancer prevention, and that led to collaboration between the World Cancer Research Fund and the American Institute for Cancer Research. Their second expert report was published recently, and was a huge undertaking, involving over 100 scientists from 30 different countries. WCRF/AICR commissioned and funded the report, but the content has been driven by an independent panel of 21 world renowned scientists. Over 5 years the group systematically collected and reviewed all the relevant global scientific literature on the subject. They then evaluated the evidence and produced consensus recommendations for reducing the risk of developing cancer and promotion of general good health and well-being. This report is the largest study of its kind, and its conclusions are as definitive as the available evidence allows.

The full report is very long and can be downloaded (free) at http://www.dietandcancerreport.org. Chapter 12 of the report features eight general recommendations for cancer prevention:

“1: Body Fatness: Be as Lean as Possible Within the Normal Range of Body Weight.” As discussed in the Lancet article, maintaining a healthy weight throughout life may be one of the most important ways to protect against cancer, and being overweight or obese increases the risk of some cancers.

“2: Physical Activity: Be Physically Active as Part of Everyday Life.”

“3: Foods and Drinks That Promote Weight Gain: Limit the Consumption of Energy-Dense Foods and Avoid Sugary Drinks.” Sugary drinks were targeted specifically in the report: “Such beverages appear to exert little influence on total daily self-selected energy intakes and their habitual consumption can lead to rapid and sustained weight gain even in the face of restricted solid food intake”. Another recommendation under this heading is “Consume 'fast foods' sparingly, if at all.”

“4: Plant Foods: Eat Mostly Foods of Plant Origin.” Diets that are protective against cancer are characterized by large intakes of foods of plant origin and, indeed, several cancers are responsive to increased intakes of plant-based foods.

“5: Animal Foods: Limit the Intake of Red Meat and Avoid Processed Meat.”

“6: Alcoholic Drinks: Limit Alcoholic Drinks.” (Men-to 2/day, women to 1/day).

“7: Preservation, Processing, Preparation: Limit Consumption of Salt and Avoid Moldy Cereal Grains and Pulses (Legumes).” Salt and salt-preserved foods are probably a cause of stomach cancer, and foods contaminated with aflatoxins are a cause of liver cancer. Although salt is necessary for human health, typical levels of consumption are vastly excessive.

“8: Dietary Supplements: Aim to Meet Nutritional Needs Through Diet Alone.” Dietary supplements are not recommended for cancer prevention. According to the report the greatest danger associated with the use of dietary supplements is the possibility that consumption of supplements is serving as an alternate to good nutrition, and supplements are taken as “magic bullets” to compensate for cancer-friendly dietary and lifestyle practices.

Changing dietary habits may not be easy, but the gathered evidence makes me hopeful. By taking steps to improve our diet a lot of diseases can be prevented.

Ayala