Wednesday, January 25, 2012

New study: Vitamin D levels of the Maasai and Hadzabe of Africa

New study: Vitamin D levels of the Maasai and Hadzabe of Africa
January 25, 2012 -- Dr John Cannell
The most frequent question we get at the Vitamin D Council is, “What vitamin D blood level should I have?” For the last seven years, we have recommended 25(OH)-vitamin D levels of around 50 ng/ml (125 nmol/L), which was our estimate of what vitamin D levels would be in very dark-skinned, scantily clothed peoples who live around the equator. Until yesterday, some of the best evidence we have had to support that recommendation comes from a 1971 study of 8 consistent sun bathing white lifeguards in Saint Louis, Missouri, whose levels ranged from 50-80 ng/ml.

Haddad JG, Chyu KJ. Competitive protein-binding radioassay for 25-hydroxycholecalciferol. J Clin Endocrinol Metab. 1971 Dec;33(6):992-5.

Yesterday, Dr. Martine Luxwolda and colleagues at the Dutch University Medical Center Groningen reported the vitamin D levels of 60 pastoral “hunter-gatherers” (35 Maasai and 25 Hadzabe), who live within a few degrees of the equator in Tanzania. All of the subjects had skin type 6, which is the black shiny skin common to those who come from equatorial regions, and also the skin type which needs the most sunlight to produce robust amounts of vitamin D. The authors added, somewhat tongue in cheek, that the natives did not use sunscreen.

Luxwolda MF, Kuipers RS, Kema IP, Janneke Dijck-Brouwer DA, Muskiet FA. Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l. Br J Nutr. 2012 Jan 23:1-5. [Epub ahead of print]

The Maasai are no longer hunter-gatherers but live, along with their cattle, either a settled or a semi-nomadic lifestyle. They wear sparse clothes, which mainly cover their upper legs and upper body, and attempt to avoid the sun during the hottest part of the day. They eat mainly milk and meat from their cattle, although recently they began to add corn porridge to their diet. Their mean 25(OH) vitamin D level was 48 ng/ml (119 nmol/L) and ranged from 23 to 67 ng/ml.

The Hadzabe are traditional hunter-gatherers. Their diet consists of meat, occasional fish, honey, fruits, and tubers. They have no personal possessions. They wear fewer clothes than the Maasai in that the men often wear nothing above the waist. Like the Maasai, they avoid the sun during the hottest part of the day. Their mean 25(OH)D was 44 ng/ml and ranged from 28 to 68 ng/ml.

Many of us have been waiting years for this data. To me, it means that the Vitamin D Council’s recommendation of 50 ng/ml is just about right, although I cannot argue with someone who recommends a level of 55 ng/ml. Remember, when errors in measuring vitamin D are made, they usually are overestimates. Thus, if mean natural levels are around 45 ng/ml, keeping your level around 50-55 ng/ml keeps you within what both the Maasai and the Hadzabe are telling us.

Burned children
January 24, 2012 -- Dr John Cannell

Dr. Cannell discusses burn victims and the importance of vitamin D in the healing process. Continue reading →

Odd case of hypercalcemia following vitamin D supplementation
January 17, 2012 -- Dr John Cannell

Dr. Cannell discusses the case of a 58-year-old woman who developed high blood calcium on a physiological dose of vitamin D, combined with an excessive dose of calcium. Continue reading →

Vitamin D supplementation for hepatitis C patients
January 23, 2012 -- Dr John Cannell

Dr. Cannell discusses the astonishing results of a new study looking at the effectiveness of hepatitis C treatment combined with vitamin D supplementation. Continue reading →

Another rickets tragedy
January 19, 2012 -- Dr John Cannell

I received the following email this morning and these cases continue to break my heart. I have been conversing over the phone with this mother, Deborah, all day. Continue reading →

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