Food fads: true, false and two kinds of maybe

kw: book reviews, nonfiction, nutrition

Finally, a genuinely useful book about nutrition, with a kind of "Mythbusters" approach to the subject: Coffee is Good for You: From Vitamin C and Organic Foods to Low-Carb and Detox Diets, the Truth About Diet and Nutrition Claims by Robert J. Davis, PhD. Dr. Davis is well equipped to tackle nutrition beliefs, as a science journalist and author of The Healthy Skeptic. By the way, coffee is good for you, in moderation, of course.

The book has 65 small chapters of a few pages each, in 10 sections. At the head of each we find a title, and a little icon displays where the title belief fits on the Truth Scale: Yes, No, Half True or Inconclusive. In an introductory section he explains several levels of supporting evidence, with the blinded clinical trial being the "gold standard", with the caveat that one must determine who paid for the clinical trial. "Studies" that embody a conflict of interest have no more weight than raw anecdotes, and perhaps less. He is careful to explain the level of support that exists for each of the 65 items.

The one I found most surprising was "Milk is Necessary for Strong Bones", with the icon "No" attached. As I read, I understood. Outside the Euro-American West, more than 2/3 of people over the age of five cannot drink milk. Lactose intolerance is the normal condition of juvenile and adult humans. I knew this, and I have a Japanese wife, one of about 30% of those Asians who can drink milk, and she does, daily. But my in-laws had never drunk milk since they were weaned. It is not the Japanese habit. What was their source of calcium and Vitamin D? Calcium came from tofu and frequent fish meals, where they usually eat the bones (Japanese eat smaller fish than Americans usually do). Vitamin D came from sun exposure. Sunscreen is practically unknown in Japan, at least prior to 2000 or so. They walked almost everywhere, so they got plenty of sunlight. Even in their mid-80s, they had strong bones. Other cultures outside the West have a variety of sources of Ca and D. And those "studies" that support milk drinking, such as the "Got Milk" ads? All funded by the dairy industry.

A number of the beliefs that got a "Yes" were really more in a "Yes, but" category. For example, Vitamin C really can affect how frequently you get a cold and how long it lasts. The catch is, too much C will loosen your stools (not always a bad thing) or cause indigestion (uncomfortable but seldom a danger). And it takes "too much" to reduce the number of colds you catch; also, the shortening is by a day at most. Not worth it for most of us.

Probably the most controversial area, whichever side you might be on, is diets, either for better health or for weight loss. The Mediterranean Diet gets a definite "Good for you", but detoxifying diets get a resounding "No." In fact, they usually do more harm than good. The irony is, the Med Diet should really be called "The Diet of Mediterranean Residents Fifty Years Ago." Most southern Europeans now eat a more American diet, and are experiencing increased obesity, diabetes type 2, and heart disease.

Probably the best advice about keeping yourself healthy and trim is something I heard last night from Chris on ABC's Extreme Makeover, Weight Loss Edition: Vary your workouts, because once your body is used to your current workout, the workout gets less effective; and something I was told by a friend who is a personal trainer: No diet plan works twice, because your body learns to cope with it and defeats you if you try it again. So the best plan is no plan, except the "table push" exercise, which is to take a small serving and to push yourself away from the table before you finish it. Period.

The funniest item is about the Caveman Diet. The author puts it in the Half True category, but warns that nobody really knows what our distant ancestors ate (He doesn't go on to say, the best evidence we have is from the "last meal" found in Ötzi the Ice Man's stomach, several dozen kinds of plant foods and just a little meat). He also recounts a cartoon from the New Yorker in which one cave man tells another, "Our air is clean, our water is pure, we all get plenty of exercise, everything we eat is organic and free-range, and yet nobody lives past thirty."

This is a useful book to keep as a reference, particularly to re-check in coming years as medicine and nutritional science march on. It is also a good read, to read right through, and take note of the particular food habits that might help you improve your own well being.