Matt Metzgar

The Evolution of Lighter Skin, Part II

I wanted to follow up ont the last post about lighter skin.  The Paleo Diet newsletter had information on this topic as well.  Apparently, lighter skin evolved due to two factors: less sunlight and the consumption of whole wheat.  The consumption of whole wheat caused additional problem with the Vitamin D metabolism.  You can see this by noting that depigmentation is not strictly related to latitude.  The newsletter concludes that:

"Thus, the extreme dermal depigmentation and high prevalence of the lactase enzyme in Northern Europeans were caused by the same negative selective pressure: high consumption of WGA containing whole wheat."

Paleobiotics

I came across this interesting website, Paleobiotics.  It looks at what dietary factors determined gut flora in Paleolithic times.  There are a number of interesting articles on the site.

You can also download this related paper(pdf), that looks at prebiotic consumption in ancient times.

Vitamin D: An Alternative View

I have written a number of times about the benefits of Vitamin D.  However, in the interest of being objective, I do want to point out that there are legitimate questions about using Vitamin D supplements.  A lot of it is summarized in this paper(pdf).

Further commentary is available on the Bacteriality website.  They make raise some interesting questions about the long-term safety of Vitamin D supplements.  In many ways, Vitamin D is a hormone.  So just as in hormone replacement therapy, introducing exogenous hormones eventually reduces the body's endogenous production of hormones.  Obviously, Vitamin D comes primarily from the sun, but the question is, why couldn't the body naturally adapt to different levels of sunlight?

I haven't fully looked into this issue yet, but I hope to see more research on it.

The Evolution of Lighter Skin

I just read an interesting paper on skin color.  The authors hypothesize that lighter skin evolved as a way to increase Vitamin D production under conditions of less sunlight at the higher latitudes.  Apparently, this theory has been around for a while, but I've never heard of it.

The authors suggest that the key is sexual selection.  Vitamin D deficiency leads to a whole host of problems including reproductive difficulties.  Therefore, it was a driver of skin color, since those with lighter skin would have been successful in reproduction at the higher latitudes.

This also explains why blacks have greater Vitamin D deficiency than whites.

Happy Thansgiving 2009!

 

Low-Carb Diets and Insulin Resistance

I was reading through the latest Paleo diet study earlier.  In just ten days, the Paleo diet lowered insulin resistance and improved insulin sensitivity to normal levels.  This is remarkable, but what I find most interesting is the amount of carbohydrates that were consumed.

Subjects in the Paleo diet consumed an average of 249 grams of carbohydrate per day.  Yet in spite of this "high" carbohydrate intake, they were able to normalize insulin function.  According to the low-carb gurus, this shouldn't be possible.

I still am baffled why some low-carb proponents suggest that low-carb is the only way to lower insulin levels.  Clearly, based on this study it is not.  You need to look at the type of carbohydrate being consumed.  Low-carb is more of a sledgehammer approach - by removing almost all carbs, you are likely to remove any bad carbs.

The Paleo Diet blog also picks up on this recently:

"So, for instance in Kitava they eat a lot of carbohydrates and still have no obesity, so it seems as if some bioactive substances of neolithic foods are responsible for hormonal disruption rather than merely carbohydrate content."

There's more to good eating than just low-carb.

Fascia II

I tell you, something still bugs me about the fascia article I mentioned last month.  In the article, Christopher McDougall writes about how is body is unbalanced.  At the end of the article, he works with Lee Saxby who prescribes some light overhead squats.  This seems to cure McDougall, though it does mention he should continue doing this exercise to maintain the results.

The way the article is written, it makes it sound as if all that is needed to straighten out fascia is a slow, weighted movement of some sort.  My question is, did the changes stick for McDougall or did the pain return?  If ever there was an article that needed a followup article, this is it.

This article leaves so many questions unanswered: why overhead squats? Why a light weight?  How long does a person have to continue doing this movement for lasting change? Does this replace all other forms of bodywork?

If this type of therapy can replace bodywork and traditional therapy, then it should be explained more.  Otherwise, a reader is left thinking it's just magazine hype.

Grass-Fed Butter

  
I ordered some grass-fed butter from PastureLand.  It's something I wanted to try.  I thought it might be a good way to get Vitamin K2 from food instead of via supplements.

Again, I can't tell much taste difference.  I don't use that much butter anyways, just to scramble some eggs occassionally.  Overall, this product is probably a minor upgrade, but hopefully an upgrade nonetheless.

Grass-Fed Beef III

I finally got a hold of some legitimate grass-fed beef.  I saw that Heart Ranch in California was having a sale with free shipping.  This turned out well for me, because the cost of the shipping from the West Coast to the East Coast would have been more than the cost of the meat!

Anyways, I tried the beef the other day for dinner.  It definitely has a different taste to it than regular beef.  At this point, I'm not sure if I like it better or worse - I can only say that it's different.  It will take a few more meals before I can tell if I really like the flavor.

Probiotics for Children

There have been a number of studies using probiotics for health conditions.  Overall, there are conflicting results.  Part of it has to due with the fact that there are different species and strains of good bacteria.

A new study appears to have got the right combination.  It tests a probiotic mix on cold and flu incidence and duration in children.  The children who received the probiotics had massive decreases in cold or flu problems over a six-month period.  Specifically, the:

• Fever incidence was reduced by 72%
• Coughing incidence by 62%
• Rhinorrhea (runny nose) incidence by 58%

Then, even if there was an incident, the duration of fever, coughing, and runny nose decreased by 48%.

These are pretty striking results.  I am actually trying to get a hold of this particular probiotic mix.  It is made by HOWARU.  The product used in this study is currently only available in Poland and Israel (I think), so it may take some time to acquire it.

Anyways, this is why you can't generalize and say "probiotics work" or "probiotics have no effect".  It all depends on the strain and combination used.  Even in this study, the combination of two strains was more powerful than just a single strand.  I look forward to more exciting research on probiotics and their health benefits.