Wednesday, December 1, 2010

Food and diets

Once again nutritional supplements are headline news. This time the benefits of vitamin D and calcium are questioned. What I find shocking is that this so-called revelation is nothing more than a rehash of what we have known to be true for more than 50 years.
Waste of money

When I went to medical school more than three decades ago I learned that osteoporosis is a bone disease affecting the bone matrix proper and that calcium supplements are of no benefit in this condition. If anything excess calcium -remember the bone is also loosing calcium here- put a burden on the kidney and increase the risk for kidney stones.

This mantra was repeated over and over again and finally ended up on a test as well. Someone was clearly concerned that we get the message. And for good reason, because then as now doctors were busily prescribing calcium supplements to anyone with evidence of bone loss. Unfortunately, such bad behavior -akin to prescribing antibiotics for viral infections- only got worse as time went by. By the 1990's doctors had moved ahead and were now recommending calcium supplements for healthy young women with no evidence of bone loss whatsoever.

It would be easy to point a finger at the pharmaceutical industry, which undoubtedly played a major role in all this. But that would be to ignore the urge of doctors to do something, even if they full well knew it was useless. Doctors and patients hate to feel helpless and nothing is more problematic in the practice of medicine than the urge to do something.

Let me be very clear on this: there is no need for any nutritional supplement whatsoever. There are no proven benefits of any supplement but there are potentially serious side-effects. Taking supplements is at best a waste of money, but more often dangerous for your health.

There is also no need for special diets. Humans can thrive on nearly any diet that includes some variety. There is no evidence that any diet is better than any other. Adults can tolerate anything, from complete carnivore to complete vegan and stay healthy. The key health issue relating to food has to do with quantity of food consumed.

The culprit in the obesity epidemic is the ubiquitous availability of cheap calorie dense food. All weight gain is due to excessive intake and all weight loss is due to reduced calorie intake. No diet offers any advantage over any other diet when it comes to weight loss. What matters is calories, pure and simple.

Athletes should eat normal food whenever possible. When offered a choice, always choose regular food  over any packaged, prepared, and especially "scientifically designed" offering. If you doubt the latter, please note that many nutrients were discovered because deficiencies were seen in people who were fed scientifically designed diets.

Endurance athletes are especially likely to obsess about food. Lack of success in many endurance events is often attributed to nutrition. The reason is simple: failure often comes with gastro-intestinal symptoms. Upset stomachs, abdominal pain, diarrhea and vomiting often go hand in hand with poor performance. But are they to blame?

Athletes are not the only ones who are quick to blame food intake. No doubt when you felt ill as a child your parents first asked if you ate something that did not agree with you. When it comes to abdominal pain, humans first think of bad food. So it is not surprising athletes blame nutrition for lack of success. Like many others, I am certainly guilty as charged. Although I have made significant errors that can be attributed to nutrition, more often than not the real issue was training.
Lake Placid 09-

When I ran my first San Francisco marathon, I was forced to stop at mile 7 with a badly upset stomach. I was quick to blame the waffles I had for breakfast. My legs felt fine! Heck I could run like this forever. It took a while to figure this out but I now know the real issue was starting out too fast. I was running 7 minute miles at the time, and although that may not impress many of you, it was way too fast for me. But the excitement of the race got to me. And it wasn't the only time that happened.

I also learned that nearly all food related issues in Ironman have one of two causes: lack of adequate training and-or excessive food or drink intake. Believe  me, you are much more likely to eat and drink too much, or go out too fast than do the opposite.

I will discuss dehydration and drinks tomorrow so stay tuned.

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