{"id":299,"date":"2014-10-29T16:13:16","date_gmt":"2014-10-29T16:13:16","guid":{"rendered":"http:\/\/joshmitteldorf.peachpuff-wolverine-566518.hostingersite.com\/?p=299"},"modified":"2014-10-29T16:13:16","modified_gmt":"2014-10-29T16:13:16","slug":"poking-fun-at-longevity-science","status":"publish","type":"post","link":"https:\/\/scienceblog.com\/joshmitteldorf\/2014\/10\/29\/poking-fun-at-longevity-science\/","title":{"rendered":"Poking Fun at Longevity Science"},"content":{"rendered":"

\u201cIn science one tries to tell people, in such a way as to be understood by everyone, something that no one ever knew before. But in the case of poetry, it’s the exact opposite!\u201d<\/b>
\n                                 \u2014 Paul Dirac<\/b><\/p>\n

Gretchen Reynolds, in her chart on \u201cLonger Living Through Science\u201d does a good job of making science into poetry. \u00a0Full of qualifications and afterthoughts and 180o<\/sup> reversals, longevity research makes an easy target for satire. \u00a0Reynolds herself has established herself as a consistent advocate for some of the clear messages concerning exercise and diet that come from this research. \u00a0As we smile, let\u2019s remember that our lives and our health hang in the balance, and through all the contradictions, there are some persistent truths.<\/em><\/p>\n

\"NYTimes-Reynolds\"<\/a><\/strong><\/strong><\/p>\n

This chart was published in the New York Times Magazine<\/a> on Sunday, summarizing the last four years of scientific studies concerning longevity.<\/p>\n

The point of the chart is to convince us that longevity science is a hodge-podge of contradictory results. \u00a0The things that consistently lead to better health and longer life are beyond our control (genes, pollution, wealth). \u00a0Among things that are<\/b> under our control, mere mortals cannot know what is effective (diet, exercise, smoking and drinking).<\/p>\n

There are many reasons that specific items in the chart are not as inscrutable as they appear. \u00a0Reynolds cites only studies of the last four years, and current research is always focused on the unresolved questions, not the well-established basics. Studies based on human longevity are the gold standard, but they must be interpreted with care since they cannot be properly controlled. \u00a0(You can\u2019t put humans in cages and vary one factor at a time. \u00a0This makes it difficult to disentangle the many correlated variables and draw conclusions about root causes.) \u00a0Studies of mice and rats are generally the best\u00a0indication of what will work in humans.<\/b> \u00a0Studies of flies and worms cannot be directly extrapolated to humans. \u00a0They are valuable for biochemical understanding and suggestions for further study; but most treatments that work to extend life in flies fail in humans.<\/p>\n

Every result cited in the chart is, in fact, a subtlety, a nuance at the edge of what we already knew about behaviors that affect longevity. \u00a0Absent from the chart was the one result that is new, and a reversal of what doctors had been recommending for decades. \u00a0Standard doctors\u2019 advice has been to minimize salt intake, and last year it was found that higher salt intake is associated with lower mortality<\/a>.<\/p>\n

Perhaps the most contentious area involves weight loss. \u00a0It\u2019s an issue frought with emotion for most of us. \u00a0On the one hand, caloric restriction has been the most robust technique for life extension in lab animals for the last 80 years. \u00a0On the other hand, using will power to eat less doesn\u2019t work for most of us, and in fact willpower has been found to backfire<\/a> and produce weight gain more often than not. \u00a0Further complication comes from social prejudices against heavy-set women. \u00a0For most women, appearance is a stronger motivater than health, and this has produced an epidemic of unhealthy dieting.<\/p>\n

I believe this phenomenon has a lot to do with why studies of BMI have failed to show any advantage to being skinny. \u00a0In fact, these results always underestimate the damage that is done by overeating. \u00a0<\/b><\/p>\n

People\u2019s weight is determined by a combination of genetics with diet and exercise. \u00a0But being congenitally overweight is not a health risk<\/b>, while overeating and under-exercising are clear health risks. \u00a0There are \u201clucky\u201d people who can overeat without gaining weight, and \u201cunlucky\u201d folks who are disciplining themselves to eat less and exercise more, because they fear that extra weight will make them unattractive. \u00a0These two people may have the same BMI, so they are lumped together in the statistics, but the latter will have much better health prospects than the former. \u00a0It\u2019s a kind of poetic justice\u2014regardless of cosmetic appearance, nature has been even-handed in rewarding temperance with health.<\/p>\n

BMI studies should be re-scaled to separate genetics from life style. \u00a0In support of this idea, results from genetically obese mice<\/a> indicate that they have exceptionally long life spans when calorically restricted, even though their appearance is not at all lean.<\/p>\n

\n

Here are some uncontroversial recommendations from the community of scientists who study human longevity:<\/p>\n