Each year at the annual meeting of the Friends of the Center for Human Nutrition, Dr. Scott Grundy, director of the Center, presents the research highlights and breakthroughs of the past year. This year, Dr. Grundy had much to brag about. The Center has made great progress in separating good fats from bad fats; in collaborating with Texas A&M University to improve vegetables, nuts and meats; in investigating the consequences of being overweight; in defining the link between nutrition, exercise and aging; and in tracing the interaction between gene expression and nutrition. The following is an edited version of his "State of the Onion" address.

GOOD FAT / BAD FAT

The Center is especially interested in dietary fats, particularly good fats and bad fats. What makes a particular fat good or bad depends on how your body reacts to it. One type is saturated fat, which is generally thought to be bad for you. This is the fat that raises your cholesterol and your chance of having a heart attack. We now know, however, that there are many different kinds of saturated fat, most of which are bad for you, including caprylic acid and caproic acid, found in butter and milk fat; lauric acid, found in coconut products; myristic acid, found in butter and coconut products, and palmitic acid, found in butter, meat and palm oil. Stearic acid, a saturated fatty acid found in beef and chocolate, does not raise cholesterol.

Dr. Margo Denke, associate professor of internal medicine and a nutrition scholar in the Center, has spent a decade research all these different kinds of saturated fats. Each year, she seems to add a new one to the list of her studies. She has discovered that all of the saturated fats except one are bad for you because they raise your cholesterol level. The one saturated fat that doesn't raise your cholesterol -- stearic acid -- is transformed in your body into a good fat called monounsaturated fat. Research in the Center has found monounsaturated fat to be a safe fat. Olive oil and canola oil are the major sources of monounsaturated fat in our diet.

THE MAROON CARROT

We have had the opportunity to work with researchers at Texas A&M who are exploring new sources of monounsaturated fats in foods. They found that pecans produced at Texas A&M are high in monounsaturated fatty acid. They have recently produced peanuts high in monounsaturates. Normally peanuts are rich in polyunsaturated fats, which are not as good for you. This new form of peanut is a much healthier variety. We also are trying to get saturated fats out of meat. Animal scientists at Texas A&M have produced a high-mono pork. Dr. Leonard Pike, director of the Texas A&M Vegetable Improvement Center, developed the 1015 onion, which is large and of high quality. Some of Dr. Pike's work is bearing new fruit -- particularly a new variety of carrot, "the maroon carrot." This carrot is high in beta carotene and other carotene products and was developed by Dr. Pike to put the discoveries of the Center for Human Nutrition into practical foods.

WEIGHED DOWN

Forty percent of American adults are moderately overweight, and 30 percent are markedly overweight. A lot of children are overweight, too, and the problem seems to be getting worse. We are investigating the consequences of being overweight from several different angles -- high low-density-lipoprotein cholesterol, high triglycerides, low high-density-lipoprotein cholesterol, high blood pressure, diabetes, coronary heart disease and cancer. A new report from the National Academy of Sciences provided evidence of a link between being overweight and developing cancer. Dr. Ronald Estabrook, a professor of biochemistry at UT Southwestern, chaired the committee that made the report. Our first goal is to understand the causes of overweight and to prevent it from occurring. Our second aim is to prevent these complications from occurring.

GET MOVING

A closely related topic is how you dispose of calories. Without a doubt, lack of exercise is an important contributor to overweight. The amount of fat you accumulate in your body is dependent upon the balance between intake and expenditure. Exercise, thus, is intimately related to nutrition.Dr. Kenneth Cooper, a member of the Center's Scientific Advisory Board, says that not only should you eat the right foods and keep calories under control, but you should also engage in 30 minutes of aerobic exercise three to five times a week and spend 30 minutes lifting weights three times a week. You can do aerobic exercise several ways: walking, cycling, running and swimming. The Center for Human Nutrition has entered into a major collaborative project with the Cooper Institute for Aerobics Research. We are working closely with Dr. Cooper and Dr. Steve Blair to understand better the interaction of nutrition and exercise. The metabolic consequences of physical inactivity are exactly the same as the consequences of being overweight. Dr. Cooper has demonstrated this very clearly. Cardiovascular fitness improves the cardiovascular system through exercise. Metabolic fitness improves total metabolism through exercise. Metabolic fitness improves the way you dispose of carbohydrates and fat, helps control cholesterol and blood pressure, and prevents diabetes. Not only is exercise important to your cardiovascular system, but it also has these lingering effects on your metabolism.

As we get older, our muscle-to-fat ratio begins to change. At age 20, you have about two-thirds more muscle than fat. At 40, the muscle is decreasing, and fat is increasing. By the age of 60, most people have half muscle and half fat. At age 80, most people have twice as much fat as muscle. These changes can't be prevented completely by diet and exercise, but they certainly can be delayed. You can slow down the change in the ratio by paying close attention to your caloric intake and by engaging in regular exercise, including muscle building.

MISSPELLED WORDS

How your body inherently responds to foods is based largely on genetics. UT Southwestern is a leader in molecular biology, which is essentially the study of genetics. The No. 1 factor in what determines natural lifespan is gene expression. Even if we were to cure all disease, most people would die between the ages of 80 and 100. Everyone's DNA is similar, but it's expressed differently, which accounts for individual responses to food and nutrition. The Center for Human Nutrition has become linked with UT Southwestern's Human Genome Project. Here at the National Institutes of Health-funded Genome Science and Technology Center, this effort is led by Dr. Glen Evans, director of the Eugene McDermott Center for Human Growth and Development.

The goal of the Human Genome Project is to determine the structure of the whole human genome. The time has come for us to apply our vast and growing knowledge of molecular biology to human problems. The link between the Center for Human Nutrition and the Human Genome Project is an important step in this direction. The genome consists of the genetic code, which is made up of the DNA in cells. The entire code is written in four letters, the four chemical components of DNA. These components are called A, T, G, C. These letters make up words, called genes. There are 3.3 billion code letters in the human genome. This is equivalent to the letters in 10 Encyclopedia Brittanicas. And all this information is packed into each cell in your body. All the code letters in the genome produce about 100,000 genes. Each gene makes one protein that is used by your body.

The proteins are the building blocks of your body and carry out its functions. The reason we are interested in these genes and the proteins that result from them is because sometimes they can go wrong. Sometimes, only a single gene, but an important gene, is abnormal. This could result from a single misspelled word - one misplaced letter out of 3.3 billion. Unfortunately, this critical misspelling can produce a severe disease, for example, congenital high cholesterol - like our previous patient Stormie Jones, and, early-onset Alzheimer's disease or familial breast cancer. Most chronic diseases don't arise from a single gene defect. Multiple gene defects result in polygenetic disease. In the Center for Human Nutrition, Dr. Jonathan Cohen, assistant professor of internal medicine and a nutrition scholar, is working with Dr. Evans to uncover the multiple genes that contribute to such common diseases as cardiovascular heart disease, stoke, most cancers, diabetes and late-onset Alzheimer's disease. Our present focus is on the genetics of coronary heart disease. What we learn can be rapidly applied to these other diseases. Dr. Cohen has started a family study project in cooperation with the Human Genome Project. He is studying a large number of individuals in different families -- more than 225 large families in which people appear to be genetically normal and 125 large families in which premature coronary heart disease is common. The goal is to determine the genetic underpinning of coronary heart disease in these families.

Another reason the Center for Human Nutrition is interested in genetics is because of the strong interaction between nutrition and genetics. For example, different foods can modify gene expression and genetic integrity. Some can turn genes off; some can turn genes on. Some foods, like antioxidants, can protect genes from being damaged, which can induce misspelled words in the genome and cause cancer. Other foods can damage genes. Genes also can affect our response to foods. Some genes enhance the effect; others reduce the response. Some are responsible for detoxifying dangerous substances in food. In the Center for Human Nutrition, we hope to identify specific gene patterns that cause nutrition-related diseases, that aggravate nutritional diseases, that increase the risk of chronic diseases and that may be targets for drug therapy.