Zinc supplements fail to meet quality standards
supplements in the US, which can be taken to treat the common cold,
do not meet quality standards according to researchers whose
findings prove just how differing mineral supplements are in their
contents and quality.
Out of sixteen zinc products that contained the mineral three failed to pass independent testing. Lower than claimed amounts of zinc were the most common problem ranging from 73 - 86 per cent of the claimed amount. In testing the zinc lozenges there was significant variation among the amount of zinc per lozenge. The suggested dose ranged from as little as 5mg per day to as much as 80mg.
In the US and Europe many people could be consuming too much of the nutrient in supplements. The Health Food Manufacturers' Association in the UK recommends an upper safety level of 15mg zinc for daily self-supplementation. The EU Scientific Committee on Food suggests total daily intake should not exceed 25mg. Both of these differ from the recommended doses of the zinc products tested by the researchers.
The nutrient, which is sold in different forms - capsules, liquid and lozenges - were evaluated by researchers to determine whether they contained the claimed and expected amount and zinc. They also screened for lead contamination and their disintegration and absorption properties. They report their findings on their website.
Of the nine pills/liquids tested three contained less zinc than claimed, ranging from 73 - 86 per cent. None of the products were contaminated with unacceptable amounts of lead. All pills (caplet and tablet) products were able to disintegrate properly.
All seven lozenges contained their claimed amount of zinc and were not contaminated with lead. Although all lozenges passed the quality testing, there was significant variation among them in the amount of zinc per lozenge and their suggested dose ranging from 5 - 80mg.
Zinc deficiency is especially common in adolescents, infants, and seniors, and is associated with diseases including chronic liver disease, sickle cell disease and diabetes. It is thought to affect around 2 billion people in the developing world. For many people, increasing the intake of zinc-containing foods or taking a zinc supplement may be beneficial to their health.
The journal BMC psychiatry (4:8) reported this month that zinc supplements may increase the effectiveness of stimulants used to treat children with attention deficit hyperactivity disorder (ADHD), the most common childhood behavioural disorder that affects around 1 in every 25 school-aged children.
However, a study in the Journal of the National Cancer Institute last February reported that a high intake of zinc in supplements may raise the risk of prostate cancer,