Those "Health" emails: Is it True What They Say About Bananas?

My old friend Marty P. sent me an email a few weeks ago entitled “Eat Bananas Friends!” I wrote back that it was ultimately a lot of silly stuff, based on half-truths, misreadings of data and leaps of faith that were ultimately a lot like the old test question answer: true; true; not related.

He wrote back and said: "Hey--when you knock something like this, you should be specific." Marty was right...so here's the email and my comments in italics following each nugget:

This is interesting. After reading this, you'll never look at a banana in the same way again.

Bananas contain three natural sugars - sucrose, fructose and glucose combined with fiber. Well, one can say that, more or less, about any fruit. So, while true, the implication is misleading in that it implies something unique about the banana. And, just for completeness sake, fructose seems to be a particularly nasty sugar.

A banana gives an instant, sustained and substantial boost of energy. Research has proven that just two bananas provide enough energy for a strenuous 90-minute workout. So what? Two bananas contain about 200 calories, the same as in about ten Tootsie Rolls (I am not, however, saying Tootsie Rolls are as good as bananas, but our dietary problem in western societies is not a lack of calories, so the bananas are not solving any issue with their calories). But according to this table, a 90 minute strenuous workout (aerobics) for a 150 lb person would burn 1,035 calories! So, this is nonsense.

No wonder the banana is the number one fruit with the world's leading athletes. As Frau Farbissina might say:

"Rilly?"

How do they know this? Where are the data showing a survey of the "world's leading athletes" reporting that they prefer bananas over passion fruit or even the lowly apple? Another unsubstantiated claim.

But energy isn't the only way a banana can help us keep fit. As I mentioned above, too much energy through food is a problem and not a solution. Energy does not keep us fit. Just more silly stuff.

It can also help overcome or prevent a substantial number of illnesses and conditions, making it a must to add to our daily diet.One cannot just make a statement like this without a shred of evidence to support it. I know of no studies which showed that in one group, eating bananas avoided certain diseases which were not avoided to the same degree in another group which did NOT eat bananas. Just nonsense.

Depression: According to a recent survey undertaken by MIND amongst people suffering from depression, many felt much better after eating a banana. Sounds like high science, doesn't it? A survey among people with depression asking them if they felt better after eating bananas? Did they also ask them if they felt better after eating chocolate? Or crab cakes? And what is MIND, anyway? I found two different MIND web sites, one in the UK and one at Harvard. I could not find a survey about bananas and depression on either.

This is because bananas contain tryptophan, a type of protein that the body converts into serotonin, known to make you relax, improve your mood and generally make you feel happier. Boy, this stuff just gets worse and worse. Tryptophan is NOT a protein, but an amino acid (and amino acids, as you will remember from high school biology are the building blocks of proteins); and yes, it is a precursor to serotonin. But bananas, per gram, contain one-one HUNDRETH of the amount of tryptophan in an egg white and one twenty-fifth as much as the same weight of turkey. This amount of dietary tryptophan will not affect your brain serotonin levels.

PMS: Forget the pills - eat a banana. The vitamin B6 it contains regulates blood glucose levels, which can affect your mood. Yes...bananas are a good source of this vitamin, but it will NOT affect your mood by helping to manage you blood sugar.

Anemia: High in iron, bananas can stimulate the production of hemoglobin in the blood and so helps in cases of anemia.Pure nonsense. Bananas do not even make an appearance on this list of non-animal sources of iron.

Blood Pressure: This unique tropical fruit is extremely high in potassium yet low in salt, making it perfect to beat blood pressure. So much so, the Food and Drug Administration has just allowed the banana industry to make official claims for the fruit's ability to reduce the risk of blood pressure and stroke. Not quite. What the FDA says is more like this: “ According to the U.S. Food and Drug Administration (FDA), eating foods rich in potassium and low in sodium may help reduce the risk of high-blood pressure and stroke.” This is from the Chiquita Banana web site. Another leap.

Brain Power: 200 students at a Twickenham (Middlesex) school were helped through their exams this year by eating bananas at breakfast, break, and lunch in a bid to boost their brain power. Research has shown that the potassium-packed fruit can assist learning by making pupils more alert.I searched the web but found no such study anywhere, including the Twickenham schools.

Constipation: High in fiber, including bananas in the diet can help restore normal bowel action, helping to overcome the problem without resorting to laxatives. Fine…it is a good source of fiber like many other fruits and vegetables. Better than some, worse than others.

Hangovers: One of the quickest ways of curing a hangover is to make a banana milkshake, sweetened with honey. The banana calms the stomach and, with the help of the honey, builds up depleted blood sugar levels, while the milk soothes and re-hydrates your system. OK—I think you all get the idea by now. I will dispense with the rest of the silliness in this email (if you really want to read it just google for bananas and depression and you will find the whole thing).

My purpose in writing these columns is to counter the bias of journalists and writers of all stripe who make false and/or misleading health claims because of ignorance, bias, agendas or all three. And, this includes anonymous "health" emails positioned to bring little-known or ignored “facts” to light. However, bananas are indeed an excellent food and should be eaten along with other fruits and vegetables regularly in a varied diet; they are not a "wonder fruit" any more than cherries or apples or cantaloupes. I will have more to say about diet next week.

Next week: The Gay Caveman Diet

The image of the Austin Powers series character Frau Farbissina was obtained at www.webwombat.com.au

© Copyright 2009 Doctor's Weekly Commentary
May not be reproduced whole or in part without citation and/or link to this site

Vitamin D--follow up

Although I promised to have more to say about vitamin D last week, I did not think I would return to this topic so quickly; however, just two days after I posted my first entry on vitamin D, Anahad O’Connor wrote an article that appeared in the Science Times section of The New York Times ( Tuesday, February 17, 2009) about sunscreens and vitamin D.

O’Connor’s piece was in the recurring Really? series (a Science Times investigation into bits of conventional wisdom in health-related areas) entitled The Claim: Sunscreen Prevents Vitamin D Absorbtion. The Facts . However, it most definitely did not have all of the facts since it presented only a single point of view in an area where expert opinion differs. And, although it is well documented that a liberal bias exists among journalists, people may not realize that bias may also extend to medical and scientific reportage. In this instance, O'Connor leans towards the orthodox dermatologic point of view (i.e., the cancer-phobic "avoid sunlight at all costs") as put forth by his expert, Henry Lim, MD a well-respected dermatologist from the Henry Ford Hospital in Detroit. So what do O'Connor and Lim say? Well, even if sunscreens do impede vitamin D production, it is negligible; and it is the fear of sun exposure (and, though unstated here, skin cancer) that is the key here.

However, while Dr. Lim is an expert in diseases of the skin, for matters related to vitamin D, I would rather hear what an expert on vitamin D has to say. (This is analogous to asking someone who rebuilds transmissions a question about a car's electrical system; they might know a bit about it since it relates to automobiles, but a better answer would undoubtedly come from someone who rebuilds electrical systems).

For vitamin D, I turn to Michael Holick, MD, PhD, who was asked to write a review on vitamin D deficiency for The New England Journal of Medicine (without a subscription you cannot get the full text of this 2007 article that I linked to within this sentence). There are few things in medicine that would more clearly identify a world-class expert than having been asked to write on a particular topic by the New England Journal of Medicine.

So, what does Dr. Holick have to say about vitamin D, the sun, deficiency and possible problems associated with insufficient D? Let's start with this quote:

According to several studies, 40 to 100% of U.S. and European elderly men and women still living in the community (not in nursing homes) are deficient in vitamin D.

But, is this important? Again, from Dr. Holick's article:

Of great interest is the role it [vitamin D] can play in decreasing the risk of many chronic illnesses, including common cancers, autoimmune diseases, infectious diseases, and cardiovascular diseases.

Hmmm...so widespread deficiency may have a role in certain common diseases. What is interesting to me in terms of The Times article is that the author did not discuss anything at all about this well-known common deficiency of vitamin D (that in some cases, may be related to sunscreen use), much less the possible public health impact of this phenomena.

Here is what Holick has to say about sun and vitamin D (D3 denotes animal-derived D and D2 plant-derived):

Sensible sun exposure can provide an adequate amount of vitamin D3, which is stored in body fat and released during the winter, when vitamin D3 cannot be produced. Exposure of arms and legs for 5 to 30 minutes (depending on time of day, season, latitude, and skin pigmentation) between the hours of 10 a.m. and 3 p.m. twice a week is often adequate.

So, before coating yourself with SPF 45 give yourself a few minutes of pure sun (and SPF 8 cuts vitamin D production in the skin by 95%).

One other point: I had thought that the author of The Times article, Anahad O'Connor might have been very sensitized to the problems of skin cancer and sun exposure since s/he was likely a freckle-faced, light-skinned individual of Celtic origins. However, I learned Mr. O'Connor is African American and thus might have been a bit more sensitive to the more widespread vitamin D deficiency in the African American community and the possible consequences of this.

Next week: those emails you get that make all sorts of health claims for common items

© Copyright 2009 Doctor's Weekly Commentary
May not be reproduced whole or in part without citation and/or link to this site

Vitamin D Levels and Muscle Strength

Vitamin D Status and Muscle Function in Post-Menarchal Adolescent Girls

This study, published in The Journal of Clinical Endocrinology and Metabolism, showed that--in a group of 12-14 y/o girls living in the UK--greater muscle strength was associated with higher vitamin D levels.

I start with this study to make a few initial points on my first blog: first, this is an observational study, and not a clinical trial; in other words, they did not divide the girls randomly into two groups and--in a blinded fashion--give one group vitamin D and the other a placebo and see if there was a difference in muscle strength.

What they did was measure the vitamin D levels and muscle strength in all the girls and see if there was a correlation. And, they found one.

But, does this association mean that the lower vitamin D levels led to relative weakness? No...it does not. Association does not equal causality, and this is a common mistake made when one draws conclusions from this type of research. For example, this could mean that the girls with the greatest strength and highest vitamin D levels were outdoors more and thus were exposed to more sunlight, yielding higher vitamin D levels.

One other point: vitamin D has several functions aside from the well-known calcium absorption and bone-building/maintenance functions (e.g., immune, cardiovascular, muscular). The dermatologists have scared the heck out of us and turned many people (mainly women) away from even the occasional ray of sun (they react to the sun as if they were vampires).

Vitmain D deficiency is quite widespread and it would be a terrific idea to get between 10 and 15 minutes of direct sunlight before smearing on the sunblock with an SPF of 45. Please folks: GET SOME VITAMIN D!! This is especially true for darker complected people (African Americans, for example) who should think of supplementation.

I will have more to say about vitamin D and health in the future.

© Copyright 2009 Doctor's Weekly Commentary
May not be reproduced whole or in part without citation and/or link to this site