Healthy Food & Healthy Living by Dr. Ayala

Is there scientific basis for the blood type diet?

Why are so many of us struggling with our weight and suffering illness? According to naturopath Dr. Peter D’Adamo knowing your blood type, and eating and exercising according to it, is the key to avoiding health and weight problems. His bestseller, Eat Right For Your Type, which was published in 1996, has been translated to more than 50 languages, and has 7 million copies in print.

I know my blood type only too well. The Red Cross is extra excited with my O negative donations (O negative blood is considered a universal donor), but as a pregnant woman I had the pleasure of receiving plenty of shots to prevent hemolytic disease of the newborn.

So how should I be eating? “Type Os thrive on intense physical exercise and animal protein”, according to Eat Right For Your Type. Uh-oh! Although I exercise regularly, I’ve never run a marathon and I’m a vegetarian; I eat lots of grains and legumes, which according to D’Adamo contribute to weight gain in my ‘type’. According to his diet I should eat a lot of lean meat, which I don’t, and avoid gluten, oranges, mushrooms, cauliflower, coffee and tea, black pepper, all vinegars and beans, which I certainly don’t. I thought I was doing fine, but imagine how much better I could be feeling.

The science behind blood type diets

Blood types are perfectly scientific. There are about 30 different antigens than can be present or absent on the surface of a red blood cell. The ABO system for typing blood, which deals with just two of these antigens (A and B), is the most well known and useful, since ABO compatibility is the most important for blood transfusion – getting incompatible blood can be fatal.  Most people have never heard of other blood types such as M, N and Kell.

But do blood types really inform about our disease susceptibility and gastrointestinal fitness?

The book offers plenty of anecdotal ‘evidence’ of people whose symptoms improved when they learned to eat for their blood type. Stories of success sound very convincing, and nothing makes as memorable an impression as personal testimony. But anecdotes are not proof.

A new study in the American Journal of Clinical Nutrition assessed the evidence for blood type diets in the scientific literature. The researchers looked for studies that grouped people according to blood type and studied whether adherence to a certain diet made a difference. Combing the entire life science and biomedical databases, the researchers could not find even one study showing an association between ABO blood type diets and health related outcomes.

Not even one!

Is it possible that blood type affects susceptibility to disease and should predict your optimal diet? It is also perfectly possible that eye color and the curliness of hair could be associated with certain dietary outcomes, and that these traits are inherited together with traits that affect gastrointestinal differences. Much like the belief that blood type is predictive of personality, the notion that blood type affects metabolism and should determine your optimal diet is a belief, in this case, based on no facts whatsoever.

I have not given birth to any children of my blood type – a bit of good news: according to D’Adamo my kids can thrive as vegetarians – so after proving I’m too lazy for  ‘intense physical exercise’ you won’t be surprised I’m also too lazy to cook seperate, individual meals for my husband and three kids.

Dr. Ayala

5 tips to help kids develop healthy flavor preferences

Research shows that although there’s a natural attraction to sweetness and saltiness, taste preference has much to do with exposure, especially early exposure. Infants usually accept whatever they’re fed, and that’s why kids around the world reflect the culinary traditions of their parents. In some cultures kids will eat spicy, sour and even bitter foods, while in others kids have a narrower range, and stick with sweet fat and salty.

When do babies develop flavor preferences?

The window of maximum plasticity in flavor openness probably occurs very early on. Studies suggest that babies whose mothers ate certain foods during pregnancy or breastfeeding tended to like these same foods later on (the flavor of foods is reflected in amniotic fluid and in breast milk, therefore the baby is exposed to mom’s flavor preferences).

A study from the Monell Center in Philadelphia, published in The American Journal of Clinical Nutrition, tried to figure out the time frame of that sensitive period – the time in which baby’s mind and palate are open and accepting to new flavors – by an interesting experiment.

The study recruited about 70 babies whose parents selected to formula feed, and assigned them to either ordinary cow-milk based formula (Enfamil), or hydrolyzed protein formula (Nutramigen) at different ages and for varying periods of time.

Now, I don’t know if you’ve tried baby formulas, but I have. Mostly out of curiosity, I’ve tasted lots of the (vegetarian) food stuffs designed for babies. I mean no offense, and this is of course just my personal opinion, but infant formulas have a unique appeal to babies only – I doubt any adult would add this milk to his morning coffee. But even more astoundingly weird tasting are the hydrolyzed protein formulas. These are the formulas that use amino acids instead of whole proteins, and are given to babies with serious allergies and intolerances. Let’s just say that they have a distinct taste and smell and are a little bitter and sour. In fact, most babies older than 4 months will outright reject the hydrolyzed protein formulas unless they’ve been exposed to it in the first months of life.

The researchers in this study, led by Julie Mennella, found that exposing babies to hydrolyzed protein formulas for 1 month was enough to make the baby open to its taste at the age of 7.5 months. Exposure to hydrolyzed protein formulas for 7 months, as opposed to 3 or 1 month, made babies more accepting of the formula, suggesting that the dose and duration of exposure matter, but what mattered most was timing.

Exposing babies to the unusual flavor was most effective when it occurred really early, and the babies accepted hydrolyzed protein formulas better at 1.5 months and 2.5 months than at 3.5 months. At 3.5 to 4 months the flavor acceptance window seemed to close and the babies just refused the Nutramigen!

Not all is lost

Although it’s easiest to introduce new flavor during the maximum acceptance window, it’s never too late to expand your kid’s palate and broaden their interest in healthy food. As we know, young kids will absorb a new language quickly if immersed in it – grammar, accent and all – while older kids and adults will have to put in more of an effort. But I think learning to enjoy new, healthy flavors is always possible, just like it’s always possible to acquire a new language – it will just take more work, and perhaps a dedicated tutor.

Five tips for developing kids’ healthy flavor preferences

• Eat well as a mom-to-be: If mom eats her fruits and veggies, baby is exposed to their flavor in-utero, a double win! 

• Breastfeed if you can: Breast milk is the ideal baby food for so many reasons. When it comes to flavor development remember that unlike formula, which is uniform, no two breast milk meals are the same, as breast milk reflects mom’s diet; therefore a breastfed baby is exposed to more flavors than a baby who is formula fed. Studies show that breastfeeding may facilitate the acceptance of new foods in childhood.

• Stay away from the sweet-salty-fatty trap: Babies and kids have a natural affinity to sweet and salt. Our job as parents is to expose our young ones to what’s good and healthy, not to what they’ll surely eat. Do your kids a favor and don’t create an expectation that all food should be sweet – expecting the usual sweet –salt-fat trifecta is a preference that can lead to a poor diet and obesity.

• Expose young kids to a variety of healthy foods: Let them experience many flavors and textures, especially in their first two years of life.

• Repeat exposures: Many studies show that repeated exposure works. Even if a vegetable is initially disliked it’s worth persisting at least eight times – kids do change their mind.

Early exposure matters, but it’s never too late to move to healthier eating habits and develop a fondness of wholesome, plant-based foods!

Dr. Ayala

Cinnamon’s for eating, not inhalation

Common sense is slow to develop in humans, and many a time young people will sit around throwing around silly ideas – and then go on to act on the silliest of them all.

And as if kids can’t come up with enough stupidity all on their own, access to a world wide web of thoughts feeds them more tricks and dares – YouTube is great at that.

The cinnamon challenge is nothing new, but I heard about it from my kids only a couple of years ago. The challenge: swallow a tablespoon of ground cinnamon in 60 seconds, without drinking fluids.

Fail to swallow a spoonful of cinnamon, and you might still have your moment of glory in this viral sensation: more than 50,000 YouTube clips, one popular clip with 30 million views (these numbers might be irrelevant by the end of today) and it’s all over Twitter. Subjecting the Cinnamon Challenge to a Google fight (fun site in which you can battle two words or phrases against each other to see which is more Internet popular) shows that cinnamon challenge with its 15 million search results is more popular than chewing gum (7 million). 

Cinnamon sounds innocent enough – every baking home has some, and what can be more natural than an ancient spice from tree bark.

So here’s an opportunity to teach kids a few basic principles in toxicology:

• Dose matters. As Paracelsus famously said: The dose makes the poison. Even water and oxygen – which we can’t survive without -- can be toxic if you have too much of them.
• Safe to eat doesn’t mean it’s safe to introduce into your body in any other way. Do you like hot peppers? So do I. They’re pleasant only by mouth. Water is fine to swallow, and to wash with, but if you inhale it it’s called drowning.

Back to the cinnamon challenge.

An article in the recent issue of Pediatrics warns that the cinnamon challenge isn’t all fun and games. Inhaling cinnamon can damage the lungs and airways, and although the effects are usually temporary, it has led to many emergency room visits, hospitalizations, and a few teens even requiring ventilator support for collapsed lungs.

You see, the cellulose fibers in cinnamon, once in the lungs, do not dissolve or break down – they stay there and are not inert. The authors, led by Steven Lipshultz, cite a study in which cellulose was introduced through the windpipe of rats. This caused inflammation and lung damage, and the results were apparent even a year after the exposure.

When a teen attempts to swallow a large mount of cinnamon there’s a pretty high risk of breathing in some of the cinnamon powder. The powder can damage the lining of the airways and lungs and even cause permanent scarring. Introducing a foreign substance into the airways is even more dangerous for people who have asthma. 

Bottom line, there are better – tastier, and more creative – uses for cinnamon.

I’m just afraid that warning kids about the dangers of the challenge – or locking the cinnamon along with the liquor as some parents have suggested – will introduce it to the few that haven’t heard about it yet, and just increase its allure.

Dr. Ayala