Mastering Nutrition

Hi, I'm Chris Masterjohn and I have a PhD in Nutritional Sciences. I am an entrepreneur in all things fitness, health, and nutrition. In this show I combine my scientific expertise with my out-of-the-box thinking to translate complex science into new, practical ideas that you can use to help yourself on your journey to vibrant health. This show will allow you to master the science of nutrition and apply it to your own life like a pro.
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Mastering Nutrition



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Aug 20, 2016

Whites have higher 25(OH)D than every other racial group, and the conventional explanation is that light skin evolved to allow sufficient vitamin D synthesis far away from the equator. In episode 24, I explain why these differences may relate to genetics of vitamin D metabolism that have nothing to do with skin color and may reflect a lower average need for 25(OH)D rather than a lower average ability to get enough. But "average" is the key word and when it comes to using this information on a practical level we need to look beyond racial categories and treat each person as an individual.

In this episode, you'll find all of the following and more: should I offer online nutrition classes?; this will start of sounding like it's about racial groups, but it's really about individuals; blacks in America have lower 25 (OH)D than whites; the conventional hypothesis explains this as dark skin being poorly adapted to these latitudes; genetic evidence suggests light skin began evolving long after the migration from Africa; aggregate global 25(OH)D data do not support the conventional hypothesis; Caucasians have higher average 25 (OH)D than non-Caucasians at every latitude; Caucasians have higher average 25 (OH)D at temperate latitudes than non-Caucasians have at equatorial latitudes; blacks in America have higher bone mineral content than whites; calcitriol dominance favors getting calcium from our food, while PTH dominance favors getting calcium from our bones; genetic variation in the 1-hydoxylase can account for the difference in 25(OH)D between blacks and whites in America, but this has nothing to do with skin color or racial groups in the way we have socially defined them; calcium intake could influence how the genetic variation translates into 25(OH)D; this does not affect white 25 (OH)D, and it could be related to calcium intake; ancestral calcium intake could have mediated selective pressure on the relevant genes; blacks in the United States have higher average calcitriol and a higher average calcitriol-to-PTH ratio than whites; similar differences between Inuit and Danes: lower 25(OH)D, higher calcitriol, and lower PTH; a traditional diet raises 25(OH)D, raises calcitriol further, and suppresses PTH further; Asians have lower 25 (OH)D than whites in Hawaii; the references ranges may in effect be applying average white requirements to drive recommendations for everyone; the Maasai and Hadza have higher 25 (OH)D, but this may be due to  higher calcium intakes, and/or higher ancestral calcium intakes that influenced their genetics; non-whites are probably adapted to lower 25 (OH)D than whites on average, but it is individual genetics rather than racial groups that are relevant; 25 (OH)D + calcitriol can be summed for a biological activity index; PTH should be in the lower half of the reference range; magnesium deficiency could confound the PTH measurement, but it probably has to be extreme.