Scientists at the University of Glasgow found that in the presence of lipid the ability of antioxidants, such as ascorbic acid (the active component of vitamin C), to protect against the generation of potential cancer-forming compounds in the stomach is less than when no lipids are present.

"Our results illustrate how diet can influence gastric biochemistry", says Emilie Combet, the post-doctoral researcher working on the project, who will be presenting her results at the Society of Experimental Biology's Annual Main Meeting on Monday 2nd of April.

The incidence of cancer of the proximal stomach has been increasing over the last 20 years for which environmental factors, such as diet, certainly play a part.

Nitrite, which is present in our saliva and is derived from nitrate in our diet, is thought to be a pre-carcinogen for gastric cancer.

When it is swallowed and enters the acidic environment of the stomach, nitrite spontaneously forms nitrosating species able to convert a range of targets, such as secondary amines and bile acids, into carcinogenic N-nitrosocompounds.

Antioxidants such as ascorbic acid protect against the formation of these nitrosocompounds by converting the nitrosating species back into nitric oxide (NO). However, NO diffuses rapidly to lipids, where it reacts with oxygen to reform nitrosating species.

The presence of lipids therefore overrides the protective effect of vitamin C against the formation of harmful compounds.

lancaster.ac

Previous research has show that mice can live up to 40% longer if they simply consume fewer calories, but a highly nutritious diet.Because people are not very good at dieting, Dr. Spindler and his colleagues would like to identify drugs which can produce the same beneficial health and longevity effects without the low calorie diet. The problem is to find a way to rapidly identify these drugs. Professor Spindler and his colleagues are examining the gene expression patterns which are induced by low calorie diets, and looking for drugs which mimic these changes. They are searching for drugs which will have these beneficial effects and slow ageing, even when they are given late in life. One drug, normally used to treat diabetic patients, seems to produce many of the beneficial effects of a low calorie diet. However, it is important to be sure that healthy people will benefit from the drug. A very low level of toxicity could interfere with the beneficial effects of such a drug, if it is taken for a lifetime.

Physiological changes associated with ageing include cell damage and the emergence of cancer cells. The most important effects of low calorie diets and longevity therapeutics given late in life may not be to prevent this damage, but instead to stimulate the body to eliminate damaged cells that may become cancerous, and to stimulate repair in damaged cells like neurons and heart cells. Low calorie diets drive the body to replace and repair damaged cells. This process usually slows down as we age, but low calorie diets make the body re-synthesise and turn over more cells , a situation associated with youth and good health. Dr. Spindler and his colleagues used their screening method to search for drugs which cause pre-cancerous and cancerous cells to commit suicide and to replace those cells with new, healthy cells. It is thought that the body does this because it normally kills some cells like damaged and rogue cancer cells to provide energy when it is starving. Then it replaces these cells when a meal is eaten.

It seems it is the total number of calories which are consumed, rather than the type of food which is the key to the effects of low calorie diets on the ageing process. However, it is known that vegetarians and fish eaters live longer than red meat eaters, and that, generally, the more fruit and vegetables in the diet, the better your health and longer your lifespan.

sebiology/