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Showing posts from February, 2013

Could the low testosterone problem be a mirage?

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Low testosterone (a.k.a. “low T”) is caused by worn out glands no longer able to secrete enough T, right? At least this seems to be the most prevalent theory today, a theory that reminds me a lot of the “tired pancreas” theory ( ) of diabetes. I should note that this low T problem, as it is currently presented, is one that affects almost exclusively men, particularly middle-aged men, not women. This is so even though T plays an important role in women’s health. There are many studies that show associations between T levels and all kinds of diseases in men. But here is a problem with hormones: often several hormones vary together and in a highly correlated fashion. If you rely on statistics to reach conclusions, you must use techniques that allow you to rule out confounders; otherwise you may easily reach wrong conclusions. Examples are multivariate techniques that are sensitive to Simpson’s paradox and nonlinear algorithms; both of which are employed, by the way, by modern software to

Calories aren't right on labels and maybe that’s OK

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Has it ever crossed your mind that the number of listed Calories (Kcals) of, say, a large, raw, whole apple at 116 Kcals and that of a glazed doughnut at 125 Kcals might not be an accurate comparison*? Surely, you might think, isn’t the doughnut more likely to add inches to your waistline? You'd be right. The difference that you might have understood intuitively is that, although the number of listed Kcals are similar, your body is likely to extract more of them from the doughnut than the apple. Why the disparity then on the Kcals listing? You can lay blame on the shortcomings of the Atwater Specific-factor System. Here's a little nutrition science history lesson: In the early 20th century, American chemist William Olin Atwater pioneered calculation of energy values from measures of heat combustion of proteins, fats and carbs. This is how we arrived to the familiar protein at 4 Kcals per gram, lipids at 9 Kcals per gram, and carbs 4 Kcals per gram. It would come to be known as

Experts on the evolution of human nutrition

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Want to eat a diet that mimics that of our Paleolithic ancestors? It might be a little more complicated than what the popular books say. The fact is, there was never one Paleo Diet; it's more likely there were hundreds of them and that they were continually changing and broadening over evolutionary time. That was the overarching message of an impressive lineup of experts on ancient human diets at a symposium entitled " The Evolution of Human Nutrition " organized by the Center of Academic Research and Training in Anthropogeny (CARTA) at UC San Diego on December 7, 2012. Now, I'm happy to report, the videos of a few of the talks have been made available (embedded in this post below). You can also read what other folks on Twitter had to say about the event using the #CARTAsymp hashtag in my Storify story . President of the Wenner-Gren Foundation for Anthropological Research Leslie Aiello, who chaired the symposium, expressed some amusement over folks who aspire to the g

The War of the End of the World: The health puzzle posed by its survivors

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The War of Canudos took place in Brazil in 1896 and 1897. Canudos was a settlement of several thousand deeply religious Christians, led by a man known as Antonio Conselheiro. They opposed the recent establishment of the Republic of Brazil, particularly the institution of income taxes and civil marriage; the former was considered government-sponsored theft and the latter a sacrilege. The republic had been declared in 1889 following a military coup that deposed Dom Pedro II, an emperor beloved by the common people and under whose rule slavery had recently been abolished. Canudos was located in the Brazilian sertão , an inhospitable semi-arid region in the northeastern part of the country. The inhabitants of Canudos were the sertanejos . The term jagunço was used to refer to the males, especially the outlaws. Many of the sertanejos lived in semi-starvation, in poor sanitary conditions, and with very limited (if any) access to healthcare. Infant mortality was very high at the time. Thos