Scientists look to DNA for Nutrition Ideas

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NEW YORK (AP) - As a registered dietitian, Ruth DeBusk has eaten a

healthy diet for a long time. As a geneticist, she wondered if she

could do better.

So earlier this year, she had her DNA tested by a company that gives

personalized nutrition advice based on genetics. The results indicated

she needed more folate.

So DeBusk doubled her minimum amount of folate, a B vitamin found in

leafy greens and citrus.

" I'm more diligent about being sure that I get it every day if

possible, because it really matters, " said DeBusk, who has a private

practice in Tallahassee, Fla., and has written a book on nutrition and

genetics.

" I'll actually make an effort to drink a glass of orange juice or eat

an extra big salad in the evening, being aware it hasn't been one of

my better folate days. "

That's the way it's supposed to work in a field called nutritional

genomics or nutrigenomics. The basic idea is this: There are genes

that affect the risk of getting illnesses like heart disease, cancer,

osteoporosis and diabetes, and the impact of those genes can be

modified by what you eat. Everybody carries one version or another of

each of those genes. So why not find out what gene versions you have

and base dietary advice on that?

" Every time we go to the supermarket we're using educated guesses

about what we should eat and what we shouldn't eat, " says

, director of the National Center of Excellence for

Nutritional Genomics at the University of California, .

In the future, more of that guesswork may be replaced with accurate,

personal DNA-based dietary advice, which says is " rapidly

emerging on the horizon. "

But that time isn't here yet, most experts say. Nutrigenomics is still

in its infancy, with plenty to be learned, and it's not yet clear what

role it may play in standard medical practice.

Most of the research targets heart disease and cancer, and scientists

may be ready to deliver personalized diet recommendations in those

areas within five years, said Ordovas, director of the nutrition

and genomics laboratory at the U.S. Department of Agriculture

Nutrition Research Center at Tufts University in Boston.

" We have scientific evidence that the concept is right, that we can

provide something along those lines in the future, " Ordovas said. " We

are not there yet. "

No? You can walk into some pharmacies or grocery stores right now and

pay $99 for a DNA test kit that will get you personalized diet advice

for heart health, bone health, or any of three other areas. It's from

Sciona Inc., a small company based in Boulder, Colo., that started

offering DNA-based diet advice in 2001. Such tests are also available

by mail order and on the Internet.

Sciona customers collect their own DNA with a cheek swab, complete a

diet and lifestyle questionnaire and send it all in for analysis.

Sciona encourages customers to review its advice with a doctor.

The company acknowledges that some scientists say it's too soon to

offer such a service, but says its testing is based on solid research.

Current testing focuses on 19 genes and the company is studying

others, said lynn Gill-Garrison, chief scientific officer and a

company founder.

Sciona's approach basically starts with standard healthy-eating

recommendations and modifies them when genetic analysis indicates a

need for something more, Gill-Garrison said.

After a DNA test, Sciona may recommend steps like eating more broccoli

or omega-3 fatty acids, she said, or limiting caffeine to protect

against bone loss.

Gill-Garrison said studies show that people with a certain version of

a gene called MTHFR tend to have high blood levels of a substance

called homocysteine, which has been linked to a higher risk of heart

disease and stroke. Studies also show that people with this gene

version can reduce their homocysteine levels by taking in more folate,

she said. So that's the advice Sciona customers with that gene version

get.

High levels of homocysteine also can be spotted with a standard blood

test at a doctor's office.

Ordovas said the trouble with anybody providing gene-based dietary

advice now is that scientists don't yet have the whole picture of what

genes should be considered. With current tests, it's like trying to

size up a landscape by looking through a keyhole, he said. You can't

tell what you're not seeing.

" At least in that very narrow region of our genome that they are

looking, they have potential that they may provide some valuable

information, and it could benefit some people, " he said. But advice

based on current tests " can also be misleading because you are

ignoring pieces that are very important, " he said.

said he doubts anybody will be harmed by the current tests,

and that they're beneficial because they get people to think about

diet and lifestyle. But he said they remind him of the first VCRs or

CD players to hit the market.

" It is an expensive new technology ... and it will probably, in my

estimation, become more efficient, more accurate and more affordable

with time. "

DeBusk, who said she has no financial ties to any of the companies,

figures the time for DNA-based diet advice has come.

" The scientist in me says we shouldn't do this now, we need to wait

another 20 years until many studies have been done, " she said. But her

clients want to know what the best science is right now, and " it's

difficult to say, 'Come back in 20 years.' You can't do that.

" Do we know everything we'd like to know? No... Do we know enough to

start introducing this type of technology and start the long process

of educating people? I would say yes. "