April 2, 2010
When micronutrients like vitamins and minerals are in short supply they are temporarily reserved for the most essential organs, at the expense of less pressing tasks. This is a survival mechanism, an example of physiological triage (1). Neglecting less essential functions on occasion may do no harm but chronic shortages due to bad diets will cause health problems in the long run.
That micronutrients are crucially important should come as no surprise. Vitamins are defined as substances that the body needs but cannot make or cannot make in sufficient quantities; and we obviously cannot make minerals. Chronic micronutrient deficiencies therefore have to be expected to take their toll.
Vitamins and minerals play numerous roles; they are antioxidants, stabilize protein structures and act as enzyme cofactors. They are therefore involved in all aspects of physiology, including such fundamental tasks as DNA maintenance and repair (2).
Inefficient or incorrect DNA repair due to micronutrient shortages leads to genome instability, a known contributor to increased cancer risk, accelerated aging and neurodegenerative diseases (2). Genome damage caused by micronutrient deficiencies is believed to be at least as common and extensive as genome damage from environmental genotoxins like chemical carcinogens, UV and ionizing radiation. Genome instability caused by micronutrient deficiencies in turn increases DNA sensitivity to environmental genotoxins.
The increase in cancer risk with increased DNA damage was demonstrated in a case-control study involving participants from Scandinavia and Italy (3). Cancer patients and matching controls were divided into three groups according to the degree of chromosomal damage found in their lymphocytes. Those in the groups with the most extensive DNA damage were 2.35 (Scandinavia) and 2.66 (Italy) times as likely to develop cancer as those with the lowest amount of damage.
Separate analyses of the data for non-smokers, smokers and people with past exposure to environmental toxins produced essentially the same results (3). In other words, it didn't matter whether the chromosomal abnormalities were caused by smoking, environmental genotoxins or other factors such as nutritional deficiencies; only the extent of DNA damage was important.
If micronutrient deficiencies cause DNA damage and DNA damage contributes to degenerative diseases, it makes sense to diagnose and try to prevent chromosomal damage by adequate micronutrient intakes. This has led to a call for adjusting recommended dietary allowances (RDAs) to optimize genome stability:
"There is a strong international awareness that it is also necessary to redefine RDA for the prevention of degenerative disease (such as cancer, cardiovascular disease and Alzheimer's disease) and compression of the morbidity phase during old age. Because diseases of development, degenerative disease and ageing are partly caused by damage to DNA it seems logical that our attention would be better focused on defining optimal requirements of key minerals and vitamins for preventing damage to both nuclear and mitochondrial DNA." (2)
Optimal intakes for most of the micronutrients known to be critical - the vitamins C, E, B2, B6, B12, folate and niacin, and the minerals zinc, iron, magnesium and manganese - haven't been determined yet. However, for those that have been studied - e.g. folate and vitamin B12 - intakes in excess of current RDA values are required to prevent chromosomal damage (2). Yet, many people don't even reach current RDA values.
Optimizing micronutrient intakes seems like an effective and affordable way to reduce the degenerative disease burdens threatening to bankrupt medical care systems in developed countries.
1. Ames BN. "Low micronutrient intake may accelerate the degenerative diseases of aging through allocation of scarce micronutrients by triage." Proc Natl Acad Sci USA 2006;103(47):17589-17594. [link]
2. Fenech M. "Nutritional treatment of genome instability: a paradigm shift in disease prevention and in the setting of recommended dietary allowances." Nutr Res Rev 2003;16:109-122. [link]
3. Bonassi S, Hagmar L, Stromberg U et al. "Chromosomal aberrations in lymphocytes predict human cancer independently of exposure to carcinogens." Cancer Res 2000;60:1619-1625. [link]