Tag Archives: vitamin D

White Skin in Europeans Only Took Off 6,000 Years Ago

Posted on April 8, 2015 | Comments Off on White Skin in Europeans Only Took Off 6,000 Years Ago

…according to an article at Science magazine. Europeans 10,000 years ago didn’t look much like those of today.

When it comes to skin color, the team found a patchwork of evolution in different places, and three separate genes that produce light skin, telling a complex story for how European’s skin evolved to be much lighter during the past 8000 years. The modern humans who came out of Africa to originally settle Europe about 40,000 years are presumed to have had dark skin, which is advantageous in sunny latitudes. And the new data confirm that about 8500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin: They lacked versions of two genes—SLC24A5 and SLC45A2—that lead to depigmentation and, therefore, pale skin in Europeans today.

But in the far north—where low light levels would favor pale skin—the team found a different picture in hunter-gatherers: Seven people from the 7700-year-old Motala archaeological site in southern Sweden had both light skin gene variants, SLC24A5 and SLC45A2. They also had a third gene, HERC2/OCA2, which causes blue eyes and may also contribute to light skin and blond hair. Thus ancient hunter-gatherers of the far north were already pale and blue-eyed, but those of central and southern Europe had darker skin.

Pale skin may be advantageous in northern latitudes because it allows production of more vitamin D.

The article also discusses European evolution of lactose tolerance and height. The ability to digest milk in adulthood apparently didn’t spread through Europe until about 4,ooo years ago.

RTWT.

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Worried About Inadequate Calcium on Your Paleo Diet?

Posted on January 27, 2014 | 1 comment

Bix at Fanatic Cook has a post on calcium and dairy consumption as regards to protection against broken hips from thin bones (osteoporosis). Or rather the lack of protection!

I’ve worried before that most paleo diets could be deficient in calcium because they don’t include milk products. Osteoporosis in adults or inadequate bone growth in kids are about the only significant problems you might see if that’s the case.

Bix quotes Harvard professor and pediatrician Dr. David Ludwig:

“Humans have no nutritional requirement for animal milk, an evolutionary recent addition to diet. Anatomically modern humans presumably achieved adequate nutrition for millennia before domestication of dairy animals, and many populations throughout the world today consume little or no milk for biological reasons (lactase deficiency), lack of availability, or cultural preferences.

Adequate dietary calcium for bone health, often cited as the primary rationale for high intake of milk, can be obtained from many other sources. Indeed, the recommended levels of calcium intake in the United States, based predominately on balance studies of 3 weeks or less, likely overestimate actual requirements and greatly exceed recommended intakes in the United Kingdom.

Throughout the world, bone fracture rates tend to be lower in countries that do not consume milk compared with those that do. Moreover, milk consumption does not protect against fracture in adults, according to a recent meta-analysis.”

Read the whole enchilada.

Another article mentions Dr. Ludwig:

People with a high-quality diet — those who get adequate protein, vitamin D and calcium from things like leafy greens, legumes, nuts and seeds — may get little or no added nutritional benefit from consuming three servings of dairy a day, Ludwig argues.

Hmmm. Wonder how he feels about grains. Sounds paleoish so far.

I’m just about ready to stop worrying about calcium.

Steve Parker, M.D.

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Too Much Calcium May Be Worse Than Too Little

Posted on April 6, 2013 | 1 comment

I’ve been fretting that the paleo diet may not provide enough calcium to keep aging bones strong. On the other hand, the writer(s) at the Joslin Diabetes Blog point out that too much calcium may promote cardiovascular disease.

The February, 2013, issue of British Medical Journal has a pertinent research report. The Joslin blogger writes:

Participants were women from a mammography cohort who were asked about their calcium consumption, using a food frequency questionnaire, at baseline and seven-to-ten years later. The 61, 433 women were followed for a period of 19 years. During that time, 6894 participants died of cardiovascular disease or stroke. The researchers found that the women taking over 1400mg of calcium per day had a higher incidence of cardiovascular disease. Participants whose calcium consumption remained within suggested bounds, between 600mg and 1000mg per day, did not appear to have a greater vulnerability to cardiac disease.

Read the rest.

I confess I haven’t read the BMJ article.

I always wonder about overall death rates when I see results like this. A group may have higher or lower rates of cardiovascular disease, and yet live longer than the comparison group. An intervention could prevent cardiovascular disease and cardiovascular death, yet increase the incidence of death from infection, cancer, accidents, or suicide, etc.

I bet a lot of adults eating a paleo-style diet approach or exceed 600 mg a day of calcium. I’m feeling better about the calcium in paleo diets. But I don’t want to have to depend on feelings.

The Joslin blogger notes that, “Perhaps it is time to have a conversation with your health care provider to determine what the best dose of calcium is for you.” Problem is, I’m not sure any healthcare provider really knows the best “dose” of calcium for the average person, whether supplemental or dietary calcium.

Sorry, men. These findings may or may not apply to you. At least you don’t have to worry about osteoporosis nearly as much as women.

Steve Parker, M.D.

PS: In case you hadn’t run across it elsewhere, note that taking a calcium supplement without a concomitant vitamin D supplement may be more harmful than taking calcium with vitamin D.

 

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Right Diet Preserves Brain Function and Size

Posted on April 12, 2012 | 1 comment

mp9004223691.jpgThe journal Neurology reports that the proper diet seems to help prevent age-related brain shrinkage and cognitive decline.

From the press release:

People with diets high in several vitamins or in omega 3 fatty acids are less likely to have the brain shrinkage associated with Alzheimer’s disease than people whose diets are not high in those nutrients, according to a new study published in the December 28, 2011, online issue of Neurology, the medical journal of the American Academy of Neurology.

Those with diets high in omega 3 fatty acids and in vitamins C, D, E and the B vitamins also had higher scores on mental thinking tests than people with diets low in those nutrients. These omega 3 fatty acids and vitamin D are primarily found in fish. The B vitamins and antioxidants C and E are primarily found in fruits and vegetables.

So the dietary pattern linked to preservation of brain size and function in this study is: high omega-3 fatty acids and vitamins B, C, D, and E. I don’t know if study participants were getting these nutrients from supplements or from food or a combination. (I haven’t read the full article.)

To find foods high in the aforementioned nutrients, you can use NutritionData’s Nutrient Search Tool.

Note that the time-honored Mediterranean diet is also associated with lower rates of dementia and slower rate of age-related mental decline.

I previously reported that a supplement cocktail of three B vitamins slowed the rate of brain shrinkage.

Steve Parker, M.D.

Reference: Bowman, G.L., et al. Nutrient biomarker patterns, cognitive function, and MRI measures of brain aging. Neurology. doi: 10.1212/WNL.0b013e3182436598

h/t to Randall Parker at FuturePundit

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