To say you might have a "broccoli gene" is a stretch, but in the not-too-far future, doctors say they'll be able to look at your DNA to determine how much — or how little — of the leafy green veggie you need to stay healthy.

It's called nutrigenomics, and it's the future of disease prevention, according to the National Cancer Institute.

"We have evidence that certain nutrients may prove more cancer-protective for one person than the next, suggesting that in another five years or so, doctors will write prescriptions for diets," said John Milner, NCI's chief of nutrition and cancer-prevention research.

Most people know vegetables, fruits and fiber are thought to fight cancer. But Milner says nutrigenomics can help determine which foods benefit which people.

"Everybody might benefit from broccoli, garlic and tomatoes," Milner said. "But a subset will receive the greatest benefit."

Scientists are still conducting complex research to determine how particular foods effect people with certain genes, so the application of this "new science" is at least five years off, Milner said.

But despite the additional work needed to bring nutrigenomics to the mainstream, Dr. Richard Shames, a California-based physician and holistic health expert, called the science "a breakthrough as great as the discovery of penicillin" in the prevention of many diseases.

"People diet, take vitamins, exercise, make lifestyle changes without really knowing if that particular maneuver is best suited for them," Shames said. "Doctors prescribe medications that are useful for 68 percent of people in a study. That is infantile compared to analyzing individuals' DNA and making specific recommendations for them."

But others in the medical community are skeptical. American Council on Science and Health Nutrition director Dr. Ruth Kava said that while nutrigenomics could be useful in fighting certain diseases, in most cases it's unnecessary.

"Propensity for obesity, for example, can be determined from family history," she said. "And the usual advice — exercise, don't smoke, eat your five servings of fruits and veggies a day — isn't going to be any less important because you can look at people's genes."

But it's the individualized nature of nutrigenomics — the fact you shouldn't just eat tomatoes but maybe eat more of them while another person should eat broccoli to fight the same disease — that makes it revolutionary, according to Shames.

"The era of one-size-fits-all health care is over," he said.

Others are concerned with privacy issues. Dr. Susan Burke, director of nutrition services for ediets.com, said nutrigenomics seems very "Big Brother."

"If insurance companies get wind of the fact that someone has a genomic tendency to heart disease, they might change his rate or penalize him for not pro-actively fighting the disease," Burke said.

Washington, D.C.-based health lawyer Larri Short said there are laws in place that forbid such genetic discrimination. But that doesn't mean it won't happen, she warned.

"It's possible an employer would choose not to promote someone genetically prone to a high-risk disease," she said.

Short was also concerned about lifestyle invasion. Just like many employers and health-care companies now offer discounted gym memberships in hopes that it'll save them money later, those genetically predisposed to a disease might be similarly targeted — and penalized if they don't take action.

Short said many Americans won't like that. "There's an ethic in this country of personal autonomy, the right to say that making a lifestyle change is not worth it," she said.

Milner conceded that there are ethical concerns to be "aired and discussed" — but he argued that nutrigenomics might actually decrease health costs — and would ultimately make people healthier.

"If we can predict who will benefit, insurance companies might embrace this," he said. "It's prevention rather than treatment."