Thursday, January 15, 2015
Should we all live on beans?
There is a book called “The Blue Zones” which researched areas of the world that have an unusual concentration of centenarians (people reaching the age of 100). Let me put up a brief summary of its conclusions before I comment:
All long-lived people live on a high-carb, low-fat, plant-based diet
All long-lived people eat a lot of vegetables, including greens.
Whenever they can get it, long-lived populations eat a lot of fruit and it seems to contribute to their longevity
When animal products are consumed, it’s occasionally and in small amounts only. But the 7th Day Adventist study also showed that vegans live longer than vegetarians or meat eaters, so the ideal is to avoid all animal products. If you do eat animal products, it shouldn’t be more than a few times a month (paleo eaters take note).
All long-lived people had periods in their life when a lot less food was available and they had to survive on a very sparse, limited diet. For example, the centenarians in the book in Okinawa describe a time during World War II when they lived on sweet potatoes for three meals a day. When discussing the centenarians in Italy: “When their family was young, in the 1950s, they were very poor. They ate what they produced on their land — mostly bread, cheese and vegetables (zucchini, tomatoes, potatoes, eggplant, and most significantly, fava beans). Meat was at best a weekly affair, boiled on Sunday with pasta and roasted during the festivals.” This reinforces my concept of periodic fasting. Because we live in a society of such abundance, we have to force ourselves to go through periods of restrictions with periodic cleanses and fasting.
All long-lived people live in a sunny, warm climate — but not necessarily tropical. They got plenty of vitamin D from natural sunshine. The warmer climate probably also contributes to less stress and a more relaxed lifestyle.
All long-lived people consume beans in some form or another.
Nuts appear to be good for health. The 7th Day Adventists who ate a small serving of nuts several times a week had about half the risk of heart disease of those who didn’t.
The typical centenarian diet is very simple. If you analyze all these diets from long-lived people around the world, they essentially eat the same simple foods every day. It appears that you do not need a wide variety of foods in your diet to be healthy. Quality food over variety is more important. Also, rich foods like meat and cheese are reserved for special occasions, and eaten at the most a few times a month if at all.
They did not constantly change their diet or jump on the latest superfood fad. They ate the same seasonal things every day of the year.
Those conclusions were derived from a study of just 5 populations -- and from a statistician's point of view a sample size of 5 is most unlikely to support accurate generalizations.
But let us accept that the generaliations are accurate and ask whether there are other factors that explain the findings. One such stood out to me as I read it: Food shortage. Note that the groups above lived on very little. A sub-demand food intake both increases longevity and reduces stature. It get you lots of long-lived short people -- as in Japan, where the food supply was very sparse for most people up until about 1960.
The effect of food shortage on stature can be extreme -- as we see in North Korea today, where the average North Korean army recruit averages out at around 4'6". And in reverse we see that the young people of Japan today are much taller than their grandparents. From memory the average has increased from about 5' to about 5'6"
So my theory that the long lives in the study groups are attributable to food shortage is thus easily testable. It follows from my theory that the individuals concerned will be very short. That should be easily testable if the authors want to advance their claims. I think there is a fair likelihood that they won't need to go back with tape-measures, however. I think they will recollect themselves towering over their study populations.
The next question concerns the California Adventists. They presumably had no food shortages, living in one of the great centers of agricultural productivity. That may be so but the Adventists could be a special case for reasons other than their food. They are also members of a very religious group and it has been observed that very religious people (also the Mormons, for instance) tend to live long and healthy lives -- presumably because both the religion itself and the community that usually comes with it de-stresses people.
But, again, let us assume that both food shortage and religion were irrelevant to the findings above. We then come to the policy decision: Is it worth it to live longer on a much less palatable diet than what we are used to? I think there is not much doubt that the majority answer is a resounding: "No". I happen to like beans but that is certainly my answer
Posted by John J. Ray (M.A.; Ph.D.).