Can your genes help create ‘designer’ diets, exercise programs for you?

Thursday, 11.24.11
Can your genes help create ‘designer’ diets, exercise programs for you?
MIAMI HERALD STAFF by Fred Tasker

Can your genes help dictate a diet that lets you lose weight without cutting calories, and know in advance whether you’d get more benefit from bike riding than from long-distance running? UM researchers are looking into it
Doctors and researchers Pascal Goldschmidt, left, dean of UM School of Medicine, Margaret Pericak-Vance, and Evadnie Rampersaud examine a gene expression chip.

Imagine a diet that would let you lose weight without cutting calories, or an exercise program that would tell in advance whether you’d get more benefit from pumping iron than walking a treadmill.

It may sound like wishful thinking or a late-night TV informercial, but researchers at the University of Miami medical school are studying the theory that nutrition and exercise can be affected by a person’s individual genetic makeup.

“I believe if we look at people at the molecular level we can improve their health,” says Sylvia Daunert, Ph.D., chair of the Department of Biochemistry and Molecular Biology at the UM Medical School. The studies question long-held beliefs about food selection and weight loss. For example, could 1,000 calories of turkey cause more weight gain in some people than 1,000 calories of cashews? If so, could a person lose weight through food selection without cutting total calories?

And could a person’s genes pre-determine whether he or she will benefit from a particular type of exercise – or perhaps be at greater risk of injury from it?

UM researchers are looking into it. “We can’t say this is 100 percent correct,” Daunert says. “This is our hypothesis. This is brand-new science.”

UM Medical School dean Pascal Goldschmidt agrees: “It’s not ready for prime time application yet.” Larger-scale studies must be done and scholarly articles vetted by peer-reviewed medical journals. Still, Goldschmidt, a co-principal investigator in the studies, says some of it could be in general use in two to five years.

The research is another offshoot of the historic 2003 success of the Human Genome Project, which mapped all the DNA, genes and chromosomes that operate the human body. Those results already fuel promising new studies into the causes and potential prevention of diseases from Alzheimer’s to Parkinson’s. Now, UM researchers hope genetics can lead the way toward creation of more individual, even “designer” programs of diet and exercise.

Genetic help in diet and exercise is crucial, Goldschmidt says, in the push to help the kinds of obese high school and college students weighing well over 300 pounds he sees regularly in the studies.

“They don’t have the discipline or education to make changes,” he says. “If we don’t want to lose them, it’s very important to find exercise routines in which they can see results pretty rapidly.”

It’s also important for older people seeking healthy food choices, he says: “When you’re 20, you can eat everything. Later, some foods work better than others.”

At UM, three studies are looking into the genetics of nutrition and exercise.

First is the role of genetics in food addiction. “Certain foods trigger addictive behavior in some individuals,” says Daunert. “They make you feel like you want more.”

Serotonin, the “feel-good” neurotransmitter, and cortisol, the “stress” hormone, might be involved, she says.

So one person might be able to eat one potato chip and stop while another would devour the whole bag.

“Different people respond differently to different foods,” Daunert says “Celiacs can’t have grain; other people can’t break down fat. It has to do with their genetic makeup.”

It’s not just that an addicted person might eat more of something. He or she also might not digest it as efficiently.

“It’s whether the bacteria in your gut breaks down the food or stores it as fat,” Daunert says.

The second study is into foods produce negative reactions — but not allergies — in the body.

“For some reason, the immune system recognizes some things we eat as foreign invaders instead of food,” says John E. Lewis, Ph.D., associate professor in UM’s Department of Psychiatry and Behavioral Science.

“It creates reactions from congestion to headache, upset stomach, bloating, indigestion,” Lewis says. “It creates chronic systemic inflammation, which can bring on serious problems. If you read the literature in the medical field, you see that inflammation is involved in many processes like diabetes, heart problems, cancer.”

UM researchers subjected 120 volunteers to blood tests designed by Immuno Laboratories of Fort Lauderdale, testing their genetic reactions to 115 foods including lobster, milk, cranberries, coconut, tomatoes and others.

Most volunteers reacted to four or five of them, Lewis said, adding that “one poor soul reacted to 40.”

“If you can eliminate these foods you calm the immune system and let the body stop reacting,” Lewis says.

Better digestion can lead to weight loss, the study said: “Subjects who eliminated the foods had reductions in weight, body mass index, waist and hip circumference, blood pressure and quality of life.” And they did it without greatly cutting calories.

The third study involves the genetics of exercise. UM researchers put 101 volunteers through a 12-week aerobic and resistance training program, measuring their physical fitness before and after with tests of how much oxygen their muscles could consume while exercising at maximum capacity.

They divided the group into “low responders” and “high responders” based on how much their fitness improved. Then they did genetic tests of the two groups and found that 437 of their genes differed — a clue to why they reacted differently to the exercises.

By repeating the tests with different exercises, they could see which volunteers responded best to, say, bike riding and which responded better to long-distance running.

“We all have the same genes,” says Evadnie Rampersaud, Ph.D., research assistant professor in the Dr. John T. Macdonald Foundation Department of Human Genetics. “But whether some genes are ‘turned on’ by exercise is predictive of what will work best.”

Adds Goldschmidt, co-principal investigator with Rampersaud on the study: “Some subjects had tremendous results. They lost weight, felt good. Others didn’t improve at all. You may benefit from lifting weights; for me, it’s better maybe to ride a bike. We propose to use genes to identify the individual response to exercise.”

But gene testing is expensive. Will this become merely an exercise aid for the rich?

“Tests are always expensive in the research phase,” says Rampersaud. “We hope the cost will go down when the tests are produced for the mass market.”

UM researchers are working on a new genetic computer chip to reduce the cost of such testing, she said.

Testing for genetic indicators for exercise and nutrition also may get simpler, Goldschmidt says. In the research phase doctors might have to identify hundreds of genes to see which affect outcomes. But once they know which genes to look for, which determine the person’s response to a particular food or type of exercise, they might have to identify only five, he said.

Read more: http://www.miamiherald.com/2011/11/24/v-fullstory/2517520/can-your-genes-help-create-designer.html#ixzz1ejyvobmx