Methods for analyzing food samples developed by an Agricultural Research Service (ARS) chemist in Maryland capture what could be considered the most definitive nutrient profiles possible for many of the foods we eat.
Craig Byrdwell, an analytical chemist in the ARS Food Composition and Methods Development Laboratory in Beltsville, has found a way to use seven different detectors—four mass spectrometers and one gas and two liquid chromatographs—to determine exactly what nutrients are in the foods we eat—and at what levels. The achievement puts him at the forefront of scientific efforts to precisely measure nutritional values of foods.
Knowing the levels of nutrients in our foods is critical to ensuring that we get enough of them as well as coming up with dietary recommendations regarding those nutrients. Vitamin D, for instance, is added to most milk, breakfast cereals and some brands of orange juice, yogurt, margarine, and some soy beverages because it is important for healthy bones and teeth.
Byrdwell's methods are the reason why scientists can say with certainty that the amount of vitamin D in a fortified serving of milk, cheese, breakfast cereal, orange juice or a soy product is at the level where it should be.
Over the years, he also has corrected misperceptions among dietary experts about the vitamin D levels in oysters (they don't have as much vitamin D as early studies indicated), identified differences in vitamin D from fish oils versus lanolin, and developed improved nutrient profiles of nutritional supplements, kale, various fruit drinks and vegetable juices and the seed oil in soybeans.
Standard methods for determining a nutrient profile usually involve exposing food samples to ultraviolet light to read their chemical signatures. Ultraviolet light will reveal the presence of vitamins, minerals and fatty acids essential for human health. But Byrdwell says that in many cases, UV readings don't give an accurate picture of a specific compound, and that his approach reveals the molecular structure, or the isomers, of nutrients. Isomers are molecules with the same chemical formula but different chemical structures, and the structure is what determines the nutrient's "bioavailability," or how well it is likely to be absorbed by the human body.
Read more about this research in the March 2018 issue of AgResearch magazine.
Photo: ARS chemists Craig Byrdwell (foreground) and James Harnly review data from a process they used to analyze the amount of vitamin D in milk, orange juice, and dietary supplements.