Lessons From Ötzi, the Tyrolean Ice Man. Part II

Otzi's Diet

Otzi's digestive tract contains the remains of three meals.  They were composed of cooked grains (wheat bread and wheat grains), meat, roots, fruit and seeds (1, 2).  The meat came from three different animals-- chamois, red deer and ibex.  The "wheat" was actually not what we would think of as modern wheat, but an ancestral variety called einkorn.

Isotope analysis indicates that Otzi's habitual diet was primarily centered around plant foods, likely heavily dependent on grains but also incorporating a variety of other plants (3).  He died in the spring with a belly full of einkorn wheat.  Since wheat is harvested in the fall, this suggests that his culture stored grain and was dependent on it for most if not all of the year.  However, he also clearly ate meat and used leather made from his prey.  Researchers are still debating the quantity of meat in his diet, but it was probably secondary to grains and other plant foods. It isn't known whether or not he consumed dairy.

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What Causes Insulin Resistance? Part II

In the last post, I described how cellular energy excess causes insulin resistance, and how this is triggered by whole-body energy imbalance.  In this post, I'll describe another major cause of insulin resistance: inflammation. 

Inflammation

In 1876, a German physician named W Ebstein reported that high doses of sodium salicylate could totally eliminate the signs and symptoms of diabetes in certain patients (Berliner Klinische Wochenschrift. 13:337. 1876). Following up on this work in 1901, the British physician RT Williamson reported that treating diabetic patients with sodium salicylate caused a striking decrease in the amount of glucose contained in the patients' urine, also indicating an apparent improvement in diabetes (2).  This effect was essentially forgotten until 1957, when it was rediscovered.

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Flu Season is Here

I've noticed everyone around me getting sick lately (I seem to have become mostly immune to colds and the flu in the last couple of years), so I took a look at Google Flu Trends. Lo and behold, the United States is currently near peak flu incidence for the 2010-2011 season. Here's a graph from Flu Trends. This year's trend is in dark blue:


Flu Trends also has data for individual US states and a number of other countries.

It's time to tighten up your diet and lifestyle if you want to avoid the flu this year. Personally, I feel that eating well, managing stress effectively, and taking 2,000 IU of vitamin D3 per day in winter have helped me avoid colds and the flu.

Vitamin D May Prevent Flu and Asthma

The AJCN just published a new controlled trial evaluating the effectiveness of vitamin D supplements on flu and asthma (1). Dr. Hiroyuki Ida's group gave Japanese schoolchildren (10 years average age) 1,200 IU of vitamin D3 or placebo per day from December through March. They found that children taking vitamin D had a significantly lower incidence of influenza A but not influenza B. These are two strains of flu that each accounted for roughly half the flu incidence in this population. Sadly, if you add the total flu incidence for A and B together (which the authors don't do in their tables), vitamin D supplementation didn't reduce total flu incidence significantly.

They also found that in the subset of children not already taking vitamin D supplements, the effect was greater, with unsupplemented children contracting nearly three times as many influenza A infections as children receiving vitamin D. They didn't analyze the influenza B or total influenza incidence in that way, so we don't know if prior supplementation makes a difference there.

The most striking finding of the paper is that the vitamin D group suffered from 6 times fewer asthma attacks than the placebo group. This needs to be repeated but it's consistent with other data and I find it very encouraging.

The paper did have some limitations. They didn't measure vitamin D status so they have no way to know exactly how effective their pill-based supplements were.

Another problem is that they began collecting data immediately after beginning supplementation. Vitamin D is a fat-soluble vitamin that can take 3 months to reach maximum concentration in the body following supplementation. By the time the children were reaching their maximum serum concentration of vitamin D, the trial was over. It would be nice to see the next trial begin supplementation in the fall and look at flu incidence in the winter.

This paper comes on the heels of another showing that vitamin D is necessary for the activation of an immune cell called the killer T cell (2). These are important for resistance to infections and cancer. Overall, these papers add to the accumulating evidence that vitamin D is important for the proper functioning of the human immune system. However, mice may not be the best model for use in studying vitamin D biology. From the first paper:

The evolution of different mechanisms for the regulation of PLC-γ1 activity in human and mouse T cells parallels the development of divergent VDR-dependent and VDR-independent antimicrobial pathways in human and mouse macrophages31, respectively, and may reflect the fact that mice are nocturnal animals with fur and humans are daytime creatures that synthesize vitamin D in the skin after exposure to ultraviolet light.

In other words, mice don't use vitamin D in the same way as humans because they have a different evolutionary relationship to it.