Kevin Klatt, PhD, RD

Pigmentation is a great model for teaching evolution and demonstrating the concept of a polygenic trait - there are a number of alleles at different loci at variable frequencies throughout the population.  This variability has been disproportionately seen across a latitudinal cline, with darker skin tones being present around equatorial regions, and a lightening seen as latitude increases. An estimated 88% of total pigmentation variation in humans can be explained by geographic differences; for reference, geography can only explain 13% of craniometric variation, another highly quantitative trait. Considering the recent evolution of modern humans, this drastic geographic distribution in pigmentation has been thought to be the result of strong selective pressures. The major differences in pigmentation are due to the amount and type of melanin synthesized in the melanocytes, and the shape and distribution of the melanosomes, organelles that transport and store melanin . Melanins are...

I'm all for sustainability - I actually ran a Sustainability Living Community in my undergraduate and was involved with a number of sustainability-related groups. The intersect between the food system, nutrition, and the environment has always interested me, and the vast array of opinions on the topic always gets a nice scientific debate going. That being said, there are some efforts that aren't always the best for you. I was at Whole Foods today and saw milk being sold in glass bottles, advertised that it came from a small farm with a nice picture of a happy cow on the front. After having just gone through Vitamins week in the class I teach, photolysis was on my mind. Milk is the highest source of riboflavin for those consuming a typical Western diet. However, riboflavin in milk is particularly susceptible to photolysis - light degrades the biochemical structure of riboflavin (1). Those glass bottles that milk is being sold in may be re-usable and considered better for the...

I really applaud anyone who is trying to make positive changes to their lifestyle, especially by improving their nutrition but, few things annoy me more than massively disseminated misinformation. The most virulent case of this is linoleic acid, an omega 6 (n-6) fatty acid. Do one google search of "Omega 6's and Inflammation" and you'll find articles on every internet health site, written by MDs/RDs/etc etc, telling you that Omega 6's, like those found in vegetable oils, are virtually the cause of every modern day ailment, from heart disease, to acne and arthritis. They'll cite you information stating that the n-6:n-3 fatty acid ratio is all out of whack. There seem to be 2 reasons that people claim linoleic acid is pro-inflammatory. 1, because it is a precursor to inflammatory molecules in the body. 2, because it is subject to oxidation, and these oxidative endproducts (reactive carbonyl compounds, ketones, aldehydes) incite an immune response . 1. Lino...

One of the most common 'anti-nutrients'/organic compounds that alternative health/ancestral diet followers seem to talk about is phytic acid. The structure of phytic acid contains an inositol group (similar to B-vitamin structures) and 6 phosphate groups. Phytic acid exists in plant foods, particularly high in nuts, seeds, whole grains and legumes. Phytic acid is a particularly important reservoir of phosphorous and other mineral cations for a plant - plants contain the enzyme phytase, which can hydrolyze the bonds between phytic acid and its bound minerals (phytic acid:mineral complexes are known as phytates). Humans do not produce phytase, though some bacteria in the human small intestine may have phytase activity, allowing for the release of a small fraction of the bound mineral. The human GI tract's pH, also, does not facilitate the liberation of minerals from their phytate complexes. Phytic acid most commonly binds to non-heme iron, zinc, and calcium (1). From an evo...

A study came out in Gastroenterology (1), that I find to be nicely timed with my most recent post on the need for controlled studies surrounding issues like gluten. I am in no way saying this is the be all end all for the gluten-free fad, but this is a scientific step in the right direction for understanding the role of gluten, if any, in medical conditions. A lot of people are avoiding gluten for a number of reasons - they think it causes weight gain, it's 'toxic', causes GI discomfort, skin problems, etc etc. Much of the information that pushes gluten-free diets is anecdotal, and doesn't control for confounding factors - when it comes to food, there are hundreds of food components/chemicals to consider, at both the macro and micronutrient levels, as well as the many interactions between said components. I must admit a pretty non-scientific sentiment- I've always been a bit skeptical of the scientific community's acceptance of gluten sensitivity. Not that ...