DOES IT WORK? Dónal O'Mathúnaexplores chromium and diabetes
CHROMIUM WAS identified as an essential trace element only in 1959. Every day we need to ingest grams of elements like sodium and calcium, milligrams of elements like iron and zinc, but even smaller amounts of the essential trace elements.
There is still some debate over how much chromium we need, but 20-40 micrograms is the usual range. The average diet in developed countries contains more than enough chromium for our dietary needs.
In 1977, several patients in hospitals being "tube fed" (receiving all their food artificially) developed diabetes. Researchers discovered that the food they were receiving contained no chromium.
When chromium was added to their diets, the diabetes went away. Biochemists later found that chromium is required for insulin to work properly in the body. This suggested that chromium is involved in sugar metabolism and thus connected to body weight, exercise and diabetes. After regulations for the sale of dietary supplements were relaxed in the States in the 1990s, chromium was widely promoted for the prevention of diabetes, for weight loss and to improve sports performance.
Chromium still makes up about 6 per cent of the dietary supplement market in the United States.
Evidence from studies
Evidence from numerous studies has clearly shown that chromium does not help people lose weight nor does it improve sports performance. However, the evidence regarding chromium and diabetes is not as clear-cut. Biochemically, chromium is necessary for insulin to work properly in the body.
People lacking chromium in their diet are more prone to develop diabetes. The big question is whether many people get insufficient chromium from their diet, and whether supplements will provide any benefit. No simple test is available for the body's chromium level.
A recent systematic review of all the research on chromium for diabetes found 41 clinical studies. Almost half of these were of poor quality. Those conducted with healthy people found no change in their blood sugar levels when they took chromium supplements.
For those with diabetes, the results varied widely. When the results of all the studies were combined, the average effect was relatively small and well within the normal fluctuation of blood sugar levels. Importantly, studies finding beneficial effects from chromium were older and of lower quality.
More recent randomised controlled trials were larger and of higher quality. These found that chromium supplements have no effect on blood glucose levels or other tests used to measure diabetic symptoms. One of the largest studies to find beneficial effects from chromium was conducted in China where the level of chromium in the diet is believed to be lower than in most developed countries. The results may therefore not be applicable in Ireland.
Problematic aspects
Chromium supplements are believed to be safe, with no clinical studies reporting any adverse effects. Harmful effects have not been found in rats given several thousand times the equivalent of an average human daily intake. The form of chromium used in supplements is completely different from industrial chromium which has been linked to some toxicity problems.
Recommendations
Chromium is found naturally in a number of foods, especially brewer's yeast, liver, wheat germ and some cheeses and cereals. The chromium content in these foods is highly variable, and processing can either increase or decrease the level.
However, such foods will provide more than enough chromium since we need so little of it. Chromium supplements usually contain chromium picolinate, chromium chloride, chromium nicotinate or brewer's yeast. Research studies have not found any differences between the effects of these different formulations.
Chromium supplements do not provide any benefits for those who are healthy. People with diabetes who get insufficient chromium in their diet might see some improve- ments if they take 200 micro- grams of chromium per day.
However, it is highly unlikely that people living in Ireland are deficient in chromium, given the tiny amounts needed in our diet.
• Dónal O'Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University. He authored Alternative Medicine: The Christian Handbook, Updated and Expanded Edition, Zondervan, 2007