Dietary Vitamin A and Vitamin D and Genetics
Continuing my arguement that vitamin A deficiency is widespread. At this point I will address a specific argument put forth by Dr. Cannell (director of The Vitamin D Council) that strikes me as particularly dumb. He states: “By the time humans could hunt large mammals, the genome had already evolved.” He goes on to claim that we evolved eating a diet similar to the Great Apes based mostly on fruit, roots, vegetables and bugs. And as evidence of the toxicity of liver he points out that eating polar bear liver can be fatal, and Antarctic explorers have died from eating the liver of their sled dogs, due to the insanely high levels of vitamin A found in these mammals.
However, the people who live in this area, the Inuit, already knew that, and while they didn’t eat the liver of these animals, they still ate livers. He also refers to one study where twin girls got vitamin A toxicity from “chronic consumption of chicken liver,” though when you look at the study they were classified as infants.
An Evolutionary Perspective on Vitamin A
Let’s look at Dr. Cannell’s opinion in light of current beliefs about evolution. First, many theories believe that it was by deviating from the diet of primates that caused us to evolve. Some think that the increased neurotransmitters provided by eating a diet high in amino acids, derived from meat, allowed the brain to grow out of its primate state. Another theory believes that famine drove apes to the sea where they began eating fish, and the extra pre-formed Omega 3 fats motivated increase brain development.
But, aside from that, no evolutionary scientist currently believes that we stopped evolving that long ago. Following is material gleaned from Time magazine, January 2010, on the new science of “epigenetics.”
Darwin postulated that evolution occurred over many, many generations and through natural selection that compounded over millions of years. Modern theory now believes that environmental conditions can cause a genetic imprint on eggs and sperm, which will pass on new traits much faster, possibly within one generation. Epigenetics is the study of patterns of gene expression that do not alter the genetic code but nonetheless change gene activity. The “epigenome” resides above the genome and essentially tell the genes to turn on or off and to express lightly or intensely. Epigenomes are triggered by environmental stressors (diet, prenatal nutrition, stress, starvation, etc) and, while they do not cause permanent genetic changes (natural selection does this), they do change the way genes express themselves. If the environmental stressors are removed the epigenetic triggers will diminish and the original genetic programming will re-establish itself.
Now, this modification of the genome can occur as easily as adding a “methyl group” to a place on a gene. “Methylation” will alter the expression of a gene and a methyl “donor” can be found in something as simple as a B-vitamin (particularly vitamin B-12 and folic acid: there is more on methylation in my book, Health Secrets, in the chapter on Vitamin B-12). So, let’s examine a fascinating little study done with this concept.
We have a species of mouse bred to have yellow coats and a strong tendency towards obesity and diabetes. One group of pregnant mice was a control and another pregnant group was given a diet high in folic acid and vitamin B-12, methyl donors with the potential to attach to the gene in question, in the womb. Within one generation, the offspring of this study group had brown coats, normal weight and no propensity towards diabetes. Simply by adding some B-vitamins to their diet.
First off, I would like to rub this study in the face of every doctor that says you are wasting your time by taking vitamins. Secondly, I would like to point out to Dr. Cannell that evolution can be rapid and flexible, because we do not have to alter the DNA, just the environment. Since humans have been eating liver for millennia it was part of our genetic expression and cannot but have been incorporated into our biochemistry. (And let us not forget that vitamin A is involved in the production of RNA, a genetic component providing cellular communication for function and renewal.)
As scientists work to map the human epigenome they discover that it is far more complicated and extensive than the human genome. The human genome-mapping project contains around 25,000 genes; the epigenetic marks are speculated at being in the millions.
As a related aside, Bruce Lipton’s book “The Biology of Belief” posits the theory, well supported, that in the human, it is not only the environment that alters our genetic expression but also our “perceived” environment. For example, if my upbringing included physical or psychological abuse, the mental patterns that formed will leave me living in an “unfriendly” universe. As a result unthreatening situations may appear to me to be threatening because I am now imprinted with a view of life that is non-supportive. My cortisol levels will rise, even from a perceived threat that is of no real danger, causing damage to my physiology and increasing my risk of diabetes, obesity, hypertension and heart disease. And I can, in turn, raise my children the same way, passing on my anxiety and fear-based motivations.
As mentioned in part one of “Defending Vitamin A”, if you wish to come to your own conclusions I strongly suggest you read Dr. Cannell’s criticisms of vitamin A (on the Vitamin D Council’s website) and then go to the Weston A. Price website to check out their scientific-based responses.