Population Health vs. Individual Health

The nutrition and development economics I study have never been more interesting to my stomach. Food safety, improved water and sanitation services, the dangers faced by people with HIV/AIDS, and the drawbacks and difficulties of best nutrition advice come to the fore, not to mention the importance of health care services and the insurance helping to pay for it all. What I also conclude is that policies are built on population recommendations, but population-based science is inappropriate -- in my case regularly inappropriate -- for individual diagnosis.

The stresses of being on the job market and work have been upsetting my stomach. While doing some routine sample tests, my doctor discovered a parasite - cryptosporidium - was lurking. His best guess is that the parasite has been dormant and could have been in there for quite some time. Antibiotics should have cleared him out by now (can I just mention how thankful I am that I don't have to pass an "organic" inspection?). If I had HIV, it could have been a deadly infection.

You usually get cryptosporidium from drinking contaminated water, but it can readily be spread from one carrier through the food system and through public swimming pools. A fellow from the NY State health department called up to make sure I was not in a position to be spreading this around. We have not been able to identify when the infection may have occurred. I'm more thankful than ever for the efforts I've reported on in the past to bring improved water sources to people who don't have them. I'm also rather thankful to have a society with someone in it checking up on people like me to try to minimize the spread of these things.

Irritable bowel syndrome isn't the only option on the table, however, and that's what gets me into the policy arena...
It could be related to a newly developed intolerance for wheat gluten [celiac disease] or dairy products. At the advice of several nutritionists, we've been adjusting our diets over the last several months to include more of the unprocessed, whole grain cereals, breads, pastas, etc. ... which contain more wheat gluten. People who promote meatless diets also tout the benefits of wheat gluten as a meat substitute. So following the advice of doctors and vegetarians may not be good for my health. But we haven't been able to determine that yet.

Then Saturday night I had to be rushed to ER for kidney stones. Now that we know I have them, I'm likely to have them again at some point in the future. There is no real way to prevent them. Once the stone has passed, I'm to take it in to the lab for analysis. In the best case scenario, the irritable bowel syndrome has caused the crystalline deposits. In the worst case scenario, the deposits are increased by some of the foods I eat ... like wheat gluten. Here we go again. While my nutritionists are encouraging me to eat a high protein diet, it may be necessary for me to go on a low protein diet to prevent further kidney stones, again in the worst case scenario.

This is all part of the real tension I see in nutrition that reminds me of the tension between micro and macro. Policies are built on population recommendations, but population-based science is inappropriate -- in my case regularly inappropriate -- for individual diagnosis. In even healthy, well-nourished populations, 5% of the people are more than 2 standard deviations from the mean in height, weight-for-age, weight-for-height and any other measure without having anything wrong with them.

I get to be an example for this one too. One part of the profession (the population-based part) tells me my ideal weight is about 190 while the clinical nutritionist with the fat monitor tells me I have a lot of lean muscle mass from working out and my ideal weight is about 215. To an epidemiologist, I would need to be 6'11" to have that as an ideal weight. Merely observing that a person is short or overweight does not mean they are not healthy or well-nourished. There's no question that I do weigh more than would be ideal for my health, but the difference is between being merely overweight and being morbidly obese.

It is extremely difficult to work all the individual cases into population policy. This is one of the reasons for greater policy humility and not trying to imagine we can legislate our way into good health. This is one of the reasons for greater research humility. What works for the person at the mean or median of the population may well not for significant portions of the rest of the distribution.