jeudi 21 novembre 2013
VITAMIN D BINDING PROTEIN: CULTURE AND MODERN MEDICINE
CULTURE, GENETICS, MODERN MEDICINE AND NON COMPLIANT HEALTH CARE PROVIDERS
Why is this Social Anthropologist writing an article about the scientific aspects of recently popularized Vitamin D? Epidemiologists, those troubadours of tragedy, while polishing their tools, find that there is Vitamin D deficiency present ubiquitously. Supplement manufacturers and their paid peon professors jump into the game recommending more and more supplementation with Vitamin D in pill forms. They ignore nature and Science, as it happens in many of the human chronic conditions that are nebulous.
Then Science comes to the rescue, scientists not paid for by drug companies lay out the dissection of Vitamin D “deficiency”.
While doing my morning reading of medical materials, on this 21st day of November 2013, the just published New England Journal had an interesting article (aren’t all medical articles interesting? Depending upon the keen mind of the reader?)
Vitamin D Binding Protein and Vitamin D status of Black Americans and White Americans
NEJM 2013, 369:1991-2000/November 21, 2013
Working with American Indians I had wondered why ALL of them had low Vitamin D levels and that in many of them, supplementation with oral Vitamin D pills did not bring up their blood levels of Vitamin D?
I was thinking along two lines.
(Malay Moslem women attending a Human Rights Conference! It is obligatory for them to wear cover up)
American Indians were all lean and now all are overweight or obese. Could there be some identifiable chemical that has caused their obesity also responsible for their low Vitamin D levels? Or what changes in hormonal metabolism occurs when a person becomes overweight or obese and how does it affect the Vitamin D levels in the blood?
Could there be some chemical produced by the bacteria in the gut that would have been necessary for proper assimilation of Vitamin D in its metabolic pathway, which is now disturbed by the relentless onslaught of artificial food and its chemical constituents? As a medical student I had a great interest in inflammatory bowel disease and bone disease including Arthritis. A study from Malaysia has shown that the presence of Inflammatory Bowel Disease has an effect on metabolic bone health but not the low levels of Vitamin D.
If you have worked as Medical Doctor in any country with large Black populations, such as Jamaica in my case, it would quickly come to your attention that Osteoporosis was very uncommon among the Blacks. And at the same time, in keeping up with their fellow blacks in the USA, Jamaican blacks are “deficient” in vitamin D despite the fact that they live in Sunny Jamaica!
It is thought that evolutionarily the necessity for Vitamin D eventually made the human skin lighter as humans went north to inhabit colder climes. It is estimated that Blacks need about 20 times the exposure of Whites to accumulate the necessary Vitamin D.
Migration to the new world occurred around 500 years ago (a forced one at that) and the body had to make some changes as it moved away from its equatorial habitat.
And this article I was reading this morning, may give us a clue how that was accomplished.
Our skins can manufacture the precursor of this hormone given the proper exposure to the sun. Bedouin and Arab women who cover themselves top to bottom are notoriously low in Vitamin D levels despite living in the desert. Even among Asians, there were racial differences. In Malaysia, in a study of post menopausal women, 70 per cent of the Malay were Vitamin D deficient where as only 10 per cent Chinese were. It is well known that Malaysian Chinese are fitter, leaner and eat better than their Malay counterparts and in the study the Vitamin D deficiency was related to Malay Race, Increased Body Mass Index and Increased Fat Mass. The fact that the Malay women were covering themselves up (a very recent phenomenon) perhaps does not help.
(Malaysian Chinese are leaner and live longer than other races in Malaysia)
Culture has something to do with your health, in the context of traditional life it may have helped you but in the context of a modern life, which may include migration, it may play havoc with your genes. East Indians who migrate to colder climes and still ate their chapattis were found to have osteomalacia in Scotland. Asians living in Southern USA have lower Vitamin D levels.
With 200 million people living in countries not of their own has a great cultural impact and the unknown effect is on the ancestral metabolism we carry with ourselves. How to adjust our genes that may be used to Curry and Dal to the vagaries of McDonalds? (an East Indian metabolism or any Asian metabolism could never adapt to McDonalds). Migrants get fat, they get more Metabolic problems than the locals (Cambodians in Australia, Guatemalans and Mexicans in the USA, Pakistanis in UK) and this would easily tie in with the article that I was reading this morning, Genes and maladaptation within a rapid time frame.
(the Bedu women who live in the desert are fiercely independent despite the fact they are completely covered, here a saudi Bedu is driving a truck, which is probited to the Arab women)
Vitamin D is manufactured in the skin and converted first in the liver to 25 dihydroxy Vitamin D and then for a second time to 1,25 di hydroxyvitamin D in the Kidney. This is the active form of the hormone, Calcitrol.
If we all have originated in Africa, as it is commonly believed, there was no need for food to contain Vitamin D and this is the case. There are very few natural nutritional sources of Vitamin D: fatty fish, fish liver oil, egg yolk.
Lately vitamin D deficiency has been touted as the cause of multiple diseases and immune deficiencies and cancer, but when is a “deficiency” on a lab test a true “deficiency” in the body?
This paper puts the first light on this matter.
25 OH Vitamin D the precursor of Calcitrol, the hormone is the major circulating form of Vitamin D; it circulates bound to a specific carrier protein, Vitamin D Binding Protein (DBP). DBP also transports Vitamin D (made in the skin by sunshine or obtain through diet: two sources in the diet, Plants give us D2 and animals give us D3 which is the more active form
In this important study published in NEJM (one reason for Doctors who read to subscribe to NEJM), Blacks had lower DBP than whites but the bioavailable 25 OH vitamin D were similar despite them being “deficient”.
Blacks, Asians, Mexicans, American Indians all have low values of 25 OH vitamin D, does this mean that they are all Vitamin D deficient and they should all take hundreds of pills? The lower levels of DBP among Blacks and Asians perhaps are an evolutionary tactic of the Great Spirit!
To complicate matters further, studies from Thailand shows that genetic variations in DBP would affect the response of Vitamin D supplementations on the 25 OH vitamin D levels!
So once again, culture, genetics interact.
So for the Doctors, it is no longer sufficient just to order Vitamin D levels and treat the results on your Electronic Health Records
: They have to know the race of the patient, mixture of the races, as Mexicans have a high rate of Native Indian blood
: They have to know the metabolic bone health status of their patients, such as Bone Density
: Currently we cannot easily measure DBP levels or DBP genetic variations
Keep in mind that Vitamin D deficiency may not be a “deficiency” at all for the majority of the populations of this world
And when repeated blood levels of Vitamin D refuse to budge, the doctors must not begin to accuse the patient of not taking the medications or increase the medications they are already on.
Instead the Health Care Provider has to become COMPLIANT with the knowledge of his patients social and cultural status