On the mark

Most of us know that sugary, fatty food choices on a daily basis can make us chronically ill. Conversely, the right food choices at every meal can prevent and even reverse ailments such as Type 2 diabetes or cardiovascular disease.

Nevertheless, the epidemic of chronic diseases related to poor dietary choices persists across the population, shortening life spans and taking a heavy toll on the economy and individual well-being.

But what if there were tests to monitor more precisely the health effects of specific foods, just as there are now clinical tests that can track cholesterol and blood sugar? Would people be more likely to eat right?

Nutrition advocates are counting on it, and they are beginning to pursue that goal by studying biomarkers that can be detected in blood, urine and tissue samples. Biomarkers can reveal how much of a specific food has been eaten and trace the complex molecular changes that take place as the body digests it. More important, they could make personalized nutrition possible by providing clear direction for doctors and patients as to what an individual should eat.

Sang’s lab is studying food biomarkers, the measurable substances in organisms whose presence indicates that exposure has occurred, so that people can more precisely tell foods’ effect on their health.

Among the top food researchers delving into this topic is Shengmin Sang, Ph.D., at N.C. A&T’s Center for Excellence in Post-Harvest Technologies at the North Carolina Research Campus in Kannapolis.

Supported with a $2.8 million grant from the U.S. Department of Agriculture’s National Institutes of Food and Agriculture, Sang is searching for biomarkers for unrefined wheat and oats. The USDA’s Beltsville Human Nutrition Research Center and the University of North Carolina at Charlotte’s College of Computing and Informatics are collaborating with him on the research.

The results of Sang’s research could be a game changer for people pursuing healthier lifestyles. His numerous published findings are a rich resource, not only for him but for other nutritional researchers worldwide. In fact, the American Society for Nutrition has identified food biomarker research as one of the most important tools for advancing the field and achieving the goal of personalized nutrition.

Over time, such new knowledge will find its way into the marketplace in the form of better products, clinical protocols, improved food processes and personalized dietary recommendations.

“I have an interest in diet and human health. Grain is the main food that people eat worldwide, so the impact of grain is huge,” Sang said. “I want to study something that will have a big impact and apply to our daily life.”

Why biomarkers for whole grains?

Whole grains are better for health than refined ones because they contain health-promoting bran and germ – components that unfortunately are removed from most grains during milling. The bran and germ contain a rich array of fiber, vitamins, minerals and phytochemicals that are important for good health. In its My Plate dietary guidelines, USDA recommends that at least half of the grains people consume should be unrefined. The department reports that although most Americans consume the recommended amount of grains, too few of those are whole grains.

Sang’s research addresses a long-standing challenge in nutritional science: the lack of tools to accurately assess how much of a specific food has been eaten and its precise effects on health. Dietary recommendations are based on research that relies heavily on questionnaires, which are notoriously error-prone.

On such questionnaires, research participants record what they eat and how often, and the results are correlated with health status in populations over time. The problem is, most people forget what foods and how much of them they ate. Nor are they always diligent about keeping food logs.

In addition, studies show that unconscious social approval bias plays a role in self-reporting. Most people exaggerate the amount of healthy food they eat and underreport their consumption of soda, chips and alcohol when asked by doctors, dietitians or questionnaires.

Nutritionists also recognize that one-size-fits-all recommendations, although helpful, fall short of promoting optimal health for everyone. For instance, such recommendations fail to account for differences among ethnic populations, many of which have evolved genetically variable responses to foods. Lactose intolerance is just one example, linked to individuals of African descent.

Nutritional science has long recognized that questionnaires are an imperfect tool for shaping dietary recommendations, but until recently, they have been the best tool available. Now, thanks to the relatively new science of metabolomics, researchers such as Sang are exploring biomarkers and how specific foods affect health.

New discoveries about grain

Biomarkers can be molecules, enzymes or hormones in blood, urine or other body fluids or tissue. To find biomarkers for specific grains, Sang first has to purify the individual compounds from grains and elucidate their chemical structures. He determines which molecules are unique to the bran portion of the grain and occur in high enough concentrations to be detected in bodily fluid samples.

Sang’s lab has reported several novel unique compounds in whole grain wheat and oats that have the potential to be used as biomarkers of whole grain intake. In published studies, he is continuously adding new discoveries to the chemical profile of wheat and oats, especially in the compounds known to promote good health.

As Sang breaks new ground, some of his findings could be useful to consumers in the here and now. He has examined 19 commercial oat products for the presence of one type of the healthful, bioactive whole-grain compounds. He found that sprouted oat bran products have the highest concentration of the compound, followed in descending order by oat meal, oat bran and, finally, cold oat cereal. Genetics, environment and post-harvest processing all play a role in how grains retain their healthful components, he reports.

Biomarkers can lead to a more personalized approach to nutrition, Sang said.

Furthermore, his lab has studied how these unique bioactive whole grain compounds are absorbed and metabolized in humans. Some of the newly identified metabolites also can be used as biomarkers of whole grain intake. Strikingly, he observed variations in the metabolism and absorption of these unique bioactive compounds among individuals.

He discovered that a certain type of intestinal bacteria is indispensable to metabolizing some of the healthful compounds that are unique to oats.

Sang and his team are adding new biomarkers to the list that he recently created and further investigating how an individual’s age, gender and microorganisms mediate the biological functions of these biomarkers in humans.

Once biomarkers for food intake become an established clinical tool, nutritionists will be able to make more accurate assessments and provide more useful advice. Such discoveries will be crucial to quantifying intake, analyzing how an individual responds to a specific food, identifying deficiencies and, ultimately, helping people achieve optimal health.

“This knowledge could be used to improve how to assess the impact of whole grain on health and provide personalized dietary advice,” Sang said.