Montana State University

From nutrition confusion to individual nutrition prescriptions

November 22, 2004 -- By Carol Flaherty

Mary Stein in a grocer's vegetable aisle. MSU photo by Erin Raley.   High-Res Available

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From carbs to no carbs to good carbs, eggs to no eggs to designer eggs, and no fats to unsaturated fats to monounsaturated fats, it's enough to make a person tune-out when the morning news on nutrition airs.

We're riding a huge wave of increasingly complex nutrition information, but we'll have extra help in just a few years, says nutrition researcher Mary Stein of Montana State University. This extra help will be in the form of knowing and understanding our own genes and how they relate to the nutrients in our diets.

Research-based information on how specific nutrients affect health "is like a tidal wave coming in right now," Stein says. This information, along with advances in understanding the human genome, will help us in the not too distant future.

"I'd estimate five years, not longer than 10 years, and our visits to the doctor will look a bit different than they do now," Stein says. "Very likely we'll have access to our own genetic information through what is known as a gene chip analysis. With this information, nutrition recommendations for optimal health will become very individualized."

To know what DNA will do for us, look at what we already know about B-vitamins and a healthy heart. One risk factor for heart disease is an elevated level of a chemical in our bodies called homocysteine. Elevated homocysteine is often due to a problem in one of two human enzyme systems, one requiring vitamin B-6 to operate properly and the other requiring folic acid (vitamin B-9).

Most people fall into one of three "genotypes" that interact with folic acid: TT, CT or CC. In people with the TT genotype, the folic acid enzyme system is less efficient. Knowing that an individual's genotype is TT, a health care provider may recommend extra folic acid and riboflavin (vitamin B-2), which can improve a person's ability to use folic acid.

Stein says some confusion will persist for quite a while, because many studies of the effectiveness of nutrients are based on supplements and others are based on food sources of these nutrients. Supplements and food sources can act differently in the human body. For instance, Stein says there are eight different kinds of vitamin E in nature. However, a dietary supplement may have only one or a few of those varieties. For vitamin E, alpha-tocopherol is the most common form in dietary supplements, though research is emerging that a different form, gamma-tocopherol has many benefits. Gamma-tocopherol is abundant in many plant food sources, especially plant seed oils. And, as important as vitamin E is, too much may be harmful.

Even though there are companies doing gene chip analysis today, Stein says we are still limited in our ability to apply this information.

"We still have a lot to learn. It's not just that genes influence how we use our food but that food also influences genes. Nutrients can turn genes on or off. Soon, we will be able to look at an individual person, their genetic make-up, their habits and goals and say 'Here is a nutrition prescription that fits your goals and may reduce your individual risk for a specific chronic disease,'" Stein says.

Stein says the good ol' Food Guide Pyramid in either its current or soon-to-be revised form will still have a place in helping us to make food choices.

"The pyramid is a population-based nutrition guide. It's a great starting point, but we need to do a better job of interpreting it. Even now, the pyramid needs to be interpreted based on age, sex and activity level. An active teenage male is at the top of the range of servings suggested by the pyramid and a sedentary post-menopausal female is on the other end."

The individual nutrition prescription will be based on the As, Cs, Gs, and Ts of our genetic codes. Our learning about the code will need to emphasize the individual, since the proteins built by genes can be turned on or off by everything from maternal attention to our adult actions.

A wise man once said that he believed the results of only two kinds of research about people: those that had a very large "N," meaning those with thousands of participants, and those with an "N of one," referring to what a person finds out is right for himself or herself. When a DNA analysis becomes affordable and the nutrition research results are interpreted in light of our individual DNA, the "N of one" will become a very powerful tool.

Contact: Mary Stein (406) 994-5640