Did you ever wonder why some people can gobble stacks of bacon day after day, without high cholesterol levels to show for it, whereas others seem to get clogged arteries just by looking at fatty foods?

General health guidelines encouraging a balanced diet full of grains, fruits and vegetables are sufficient in helping the majority of people prevent obesity and related diseases. But each of us is somewhat biochemically distinct, woven out of singular genetic strands that influence metabolism and other body functions.

And scientists from the hottest area of nutrition research -- it's celled nutrigenomics -- are busy determining which specific dietary approaches are best suited to the individual biochemical profiles dictated by our genes. After all, we are what we eat, and foods can be viewed as tasty chemical parcels.

Nutrigenomics aims to identify the effects that the nutrients in your food have on the function and expression of the genes in your body.

An outgrowth of the Human Genome Project, the field examines genes that have already been established as markers for disease. Then it tests how common mutations of those known genes can be encouraged or discouraged to carry out their plans, so to speak, via the chemical intervention of particular nutrients.

"With more personalized nutritional genomic information," says Jose Ordovas, senior scientist and director of the Nutrition and Genomics Laboratory at Tufts University, "we will be able to use diet as a primary disease prevention tool, in a precise way."

The research sounds more like science fiction than actual fact: A doctor swipes the inside of your cheek with a Q-tip, and after a quick analysis, produces tailor-made dietary recommendations. It is this highly personalized approach to nutrition that may spark the psychological motivation people need to change dangerous eating patterns, Ordovas says.

"When we give global dietary recommendations, people typically don't adopt them. They think they apply to other people, but not to them. It would be better to say, 'You have to take this because your genes say so!'"

Ordovas' team is currently teasing apart genetic factors contributing to obesity. He envisions a time when an overweight person can be virtually guaranteed that if they follow a particular path they will successfully lose weight and maintain their weight loss.

This much he can say so far. "Some people, for example, will be told to concentrate on limiting certain kinds of fats, whereas others will be told to reduce their total fat intake."

There's a lot of individual genetic variation that influences our propensity to obesity and cardiovascular disease, the number one health threat in the U.S. and Ordovas' main research focus. A lot of it revolves around our imprinted reaction to the modern diet.

"Some people can accommodate the fact that our diet has changed since ancestral times better than others," says Ordovas. Large-scale population studies have revealed that some ethnic groups have genetic mutations that particularly influence their response to diet. Hispanics and Native Americans in the U.S., for example, are especially prone to diabetes. For those at risk, a modified diet could prevent the expression of the mutation that leads to the disorder.

Genes are not necessarily destiny. They are influenced by the chemistry of what we consume. Ordovas expects that we will be benefiting from practical applications of nutritional genomics by the year 2010.