By Dr. Ananda S Prasad
In 1974 the Food and Nutrition Board of the U.S. National Academy of Sciences made a landmark decision, to declare zinc an essential nutrient and establish recommended dietary allowances for humans.
Later, including zinc in total parenteral nutrition fluids was made mandatory, which undoubtedly saved many lives. Dietary zinc deficiency is very prevalent in the developing world (affecting nearly 2 billion people) where mainly cereals are consumed by the population. A meta-analysis of 33 prospective intervention trials of zinc supplementation and its effects on children's growth in many countries showed that zinc supplementation alone had a statistically significant effect on linear growth and body weight gain, indicating that other deficiencies that may have been present were not responsible for growth retardation.
Zinc supplementation has been shown to improve neuropsychological functions in Chinese children with zinc deficiency. It reduces the incidence and duration of acute and chronic diarrhea and acute lower respiratory tract infections in children in developing countries, resulting in decreased mortality. Zinc deficiency in pregnant women causes:
- Abnormal labor
- Retarded fetal growth
- Fetal abnormalities
The immunological effects of zinc deficiency during the early 1960s were not known, although I knew that patients with zinc deficiency in the Middle East died of infection before the age of 25 (personal observation). It has now been shown that in people with zinc deficiency:
- Activity of serum thymulin (a thymus specific hormone involved in T cell function) is decreased
- An imbalance between T helper cell (Th1) and Th2 function develops
- Lytic activity of natural killer cells and the percentage of precursors of cytolytic T cells are decreased
Zinc deficiency has now been recognized to be associated with many diseases--for example:
- Malabsorption syndrome
- Chronic liver disease
- Chronic renal disease
- Sickle cell disease
- Other chronic illnesses
In these conditions, deficiencies of other micronutrients such as vitamins and other trace elements may also be associated. It should be emphasized that nutritional zinc deficiency in the developing countries does not occur in isolation.
Recently the National Institutes of Health's Eye Institute conducted a large double blind clinical trial including 3,640 elderly participants, which showed that antioxidants and zinc supplements delayed progression of age related macular degeneration and reduced the risk of loss of vision. Zinc deficiency is also common in elderly people.
Zinc decreases the copper burden in humans; as such it has been used effectively to treat Wilson's disease. In therapeutic doses, zinc has been shown to be beneficial in the treatment of:
- Hepatic encephalopathy
- Sickle cell disease
- The common cold
More than 300 catalytically active zinc metalloproteins and more than 2,000 zinc dependent transcription factors involved in gene expression of various proteins have been recognized.
The problem has been known for 40 years and a solution is still outstanding. Despite all the evidence, practically no attention has been given by the world's organizations to the problem of zinc deficiency. Growth retardation and increased susceptibility to infectious and cognitive impairment are common in developing countries where nutritional deficiency of zinc is also prevalent.
British Medical Journal February 22, 2003;326:409-410 (Full Text Article)
This is an excellentcomprehensive review on zinc from one of the top zinc researchersin the world. While zinc is an essential component of humannutrition and deficiency can result in some devastating symptomsas discussed above, it is important to avoid the traditionalparadigm approach to nutrients.
Most physicians,natural medical doctors and patients have a strong tendencyto target nutrients for specific diseases. I believe thisis an artifact of being so long rooted in the drug-based healthcare model. Most of you realize that I am a minimalist whenit comes to using supplements but still use them quite a bitwhen indicated.
The key to supplementuse is understanding who needs them and when. This usuallyinvolves an individual assessment so that the individual withthe disease is treated--not the disease. This is an importantdistinction; if you supplement with nutrients indiscriminatelyit is clear they can cause quite serious damage. I have seenthis happen all too frequently in many well-intentioned professionalsand patients.
Fortunately,nutritional typing inconjunction with hair analysis is often helpful in providingthis individualized assessment. I hope to share more detailson this topic later this year, but in the meantime my goodfriend and top-notch nutritionist David Vaughan provides thefollowing pearls on zinc:
People who buildor move into new homes with copper pipes should supplementwith zinc for a year or two. Copper pipes are a huge unmentionedproblem with very long lasting and devastating effects. Ithink research would show a big increase in cancer (especiallyfemale hormone related cancers) from copper plumbing. I alsobelieve there is a strong link between the so-called ADHD/ADDepidemic and copper plumbing. Wouldn't proving that mess upthe plumbing industry?!