A-Z of vitamins & supplements. Zinc -- should you really be taking it?
Zinc is often taken as an 'over-the-counter' drug to reduce the chances of getting the common cold, to improve physical fitness when training, and to enhance the immune system in auto-immune conditions such as rheumatoid arthritis.
But what does the research say about zinc supplementation? Does it really work in these conditions and if so how much should you take?
Like high dose vitamin C, there is reasonable scientific evidence that oral Zinc supplements, taken within 24 hours of the onset of the common cold, reduces the duration of illness. More interestingly, if zinc is taken for at least five months throughout winter, it has positive affects on other aspects of the immune system, reducing antibiotic use in children. So who else should be taking this vitamin? In countries where food shortages and health care infrastructure is lacking, due to drought or war, It is more common to see children with malnutrition, or an undiagnosed problem with absorption of food, such as ceoliac disease or inflammatory bowel disease. In both these cases, zinc which is an essential vitamin, will be replaced to avoid long term health affects.
Some older people will also take Zinc in the hope of reducing their chance of Alzheimer's disease. It has long been known, through our knowledge of Wilson's disease (an inherited condition where the body cannot excrete copper through the intestines and so it builds up in the blood) that excess copper can affect nerve fibers. Over the last 100 years, the incidence of dementia and Alzheimer's disease has been steadily increasing. This increase has been linked to environmental changes and a hypothesis known as " Brewer Hypothesis " suggests that we are insidiously absorbing excess amounts of inorganic copper (copper salt) from water flowing through copper pipes or from fertilisers that directly affects the water systems and the food we eat. It is a controversial area. Because there is no agreement that excess inorganic copper actually is the cause of Alzheimer's disease, we, in the National health service (NHS), do not have allocated resources to perform routine blood tests to assess copper levels before and after starting Zinc.
As for athletes, the scientific community are still unsure if this can really improve performance, with just one study showing benefit. Time will tell.
Despite its role in regulating the immune system, evidence to support its use in rheumatoid arthritis and Systemic lupus erythematosis, to control disease is lacking. This, however, has not stopped many alternative health care practitioners prescribing higher doses than the daily recommended dose, to patients with autoimmune diseases. Perhaps a role for low dose zinc could be permitted with the intention of preventing common infections, of which this patient group is often at increased risk. See main Zinc article which refers to clinical studies.
As for testing your Zinc level, If you are not vegetarian and do not have active inflammatory bowel disease, it should be normal; however, Zinc levels have also been found to decrease as you age. This may be part of the aging process or a more attractive hypothesis currently under investigation is that low levels of zinc cause aging. The latter implies that taking zinc could prevent aging, but studies in humans have not yet confirmed this. In the UK zinc is not routinely checked on the NHS. so you have to go to a private laboratory and have a blood test, which is costly. Zinc levels vary diurnally so it depends on the time day that you have the test carried out.
So, what foods should you eat to maintain your zinc levels?
Eating a varied diet of fish, eggs, nuts, and meat will keep your Zinc levels normal if you are otherwise healthy. If you are a strict vegetarian then you may benefit from taking a zinc supplement. If you feel you are not obtaining sufficient Zinc in your diet then recommended supplement should not exceed 25 mg/day. Nasal zinc sprays should be avoided as they have been linked to permanent loss of smell.
Zinc supplements taken for five months during the winter period seem to be useful for everyone living in colder climes, to prevent the common cold. It continues to be used in patients with Wilson's disease and in children with malnutrition. As yet, there is no agreement on its use in the prevention of Alzheimer's disease, given that 'brewers hypothesis' has not been widely accepted. Further studies are required to better understand whether aging could be slowed by taking zinc, and whether athletes could improve their performance. Strict vegetarians should take a supplement as recommended, not exceeding 50mg per day. Zinc nasal sprays should be avoided due to their side-affects. There is currently no indication to check your zinc level, which varies with the time of day.
If you'd like to know more, you can read my A-Z of vitamins under nutrition.