Gene expression technology to provide new data on vitamin C safety

Related tags Gene Dna

State-of-the-art gene expression technology is being used in a new
trial to assess the safety of high doses of vitamin C.

It is thought to be the first time such technology has been used to measure the safety of a vitamin and is expected to produce more accurate results than those previously extracted from older studies.

The maximum level of vitamin C that can be safely taken in supplement form has been hotly debated by industry and scientists.

One of the best-known vitamins, vitamin C is an antioxidant that has been linked in epidemiological studies to prevention of cardiovascular disorders and cancer. Some research has tested very high doses of the vitamin to investigate whether it could act as a preventative against chronic disease, and while results have not been conclusive, some consumers consume high doses to maximize the potential benefit.

But while the UK supplement industry recommends an upper safe level of 2000mg vitamin C, or 3000mg for short term usage, a report last year from experts commissioned by the Food Standards Agency recommended that the upper level should be limited to 1000mg based on potential side effects like stomach cramps, diarrhoea and flatulence.

There has also been some lab research in 2001 suggesting that the vitamin could produce toxins that damage DNA.

Many experts were suprised by the FSA report findings and most agree that there is little evidence of toxicity from high doses of the vitamin. New evidence to support the safety of doses up to 2000mg will be valuable to the supplement industry.

"There is no evidence that high doses are toxic but we do not know as the information isn't out there,"​ said Professor Joseph Lunec head of the Genome Instability Group within the Department of Cancer Studies and Molecular Medicine at the University of Leicester, who is heading up the trial.

A major part of the FSA-funded project involved establishing assays for routine analysis of intracellular vitamin C and markers of DNA damage. Prior to carrying out the dosing study in human volunteers, the toxicity of vitamin C was established in cultured cells and gene expression studied.

"Any food will affect expression of genes so we are looking to see if these different amounts of vitamin C are inducing any genes associated with good or bad effects,"​ Professor Lunec told

"Nobody has used gene expression data before,"​ he added. "We hope it will be more accurate as it will take into account all potential expression of genes. Other studies have looked at very specific effects."

The University of Leicester was one of the first institutes to get a microarray machine developed for gene profiling. Professor Lunec is now recruiting 280 healthy adults to supplement their diets with doses of up to 2000mg vitamin C a day.

The trial is expected to conclude by the end of the year.

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