Researchers from the University of Alaska, Fairbanks, have discovered a biomarker that can measure how much sugar a person has consumed in his or her diet in the past few months.

With obesity on the rise, a great deal of research is devoted to understanding the biology of weight gain. However, scientists can only study what they can accurately measure, and measuring a subject’s diet is notoriously difficult.

“Measuring what people eat is actually very difficult,” explained Diane O’Brien, an associate professor of biology at the University of Alaska, in an interview with Healthline. “Most people can't estimate intake very accurately, especially over long time spans like months. For dietary sugars and sugar-sweetened beverages, self-reporting is even more problematic—people tend to under-report what they view as their ‘less healthy’ dietary behaviors, and to an unpredictable extent.”

As the body grows new cells, it uses materials drawn from the person’s diet. Traces of those materials are used to create new amino acids, the building blocks used to manufacture proteins. The study, led by O’Brien, found that the sugar from sweetened beverages leaves a distinctive marker in the body’s proteins as they produce new hair and blood cells.

One of These Carbons Is Not Like the Others

According to a report from the Harvard School of Public Health, half of Americans drink at least one sugar-sweetened beverage every day. Most of this sugar comes from sugar cane and corn syrup.

Unlike most of the crops grown in the United States, sugar cane and corn are both tropical grasses. Tropical plants undergo a different photosynthesis process than cooler-climate plants when they use sunlight to make food, and in the process, they select a type of heavy carbon called carbon-13.

But we don’t get carbon-13 from sugar alone. Livestock like chicken and cattle that have been corn-fed will also have carbon-13 in their meat. To home in on sugar, O’Brien’s team examined one particular amino acid called alanine. The body manufactures alanine from sugar, rather than by taking apart proteins found in meat, making alanine an ideal sugar intake marker. Once the alanine is used to create hair or blood proteins, it can be measured.

As with some illicit drugs, traces of sugar remain at measurable levels in the body for quite some time. O’Brien explains, “Red blood cells only live about 90 to 120 days, and the time for 50 percent of your red blood cells to be replaced is about two months. So red blood cells reflect diet integrated over a period of one to three months. Hair grows at about 1 cm a month. So, if you have a crew cut, your hair is only reflecting diet over the last few weeks. If you are Rapunzel, you've got a [carbon-13] record over your entire lifetime!”

Sugar From Any Other Plant Would Taste as Sweet

Although O’Brien’s results are promising, follow-up tests will have to be done to establish the efficacy of this test worldwide. Her team examined the Yup’ik, a native population in southwest Alaska. The Yup’ik consume fewer processed foods and corn products than the general American population.

“The marker works really nicely in the Yup’ik population,” O’Brien said. “I think it would work well in other U.S. populations, but we need to test it against other dietary backgrounds to see how generalizable it is and how well it would work across other populations.”

In particular, the Yup’ik don’t eat very much sugar from the other primary sugar source in the United States, the sugar beet. Sugar beets, native to Europe, do not process heavy carbon the way corn and sugar cane do. According to the U.S. Department of Agriculture, sugar beets make up more than half of the country’s sugar production.

O’Brien’s method would miss sugar from this source. In Europe and Japan, which make sugar almost exclusively from sugar beets, this measurement might not be useful at all.

However, despite this limitation, O’Brien’s test still remains far more accurate than anything currently available. It could be used as a basis of comparison to develop additional tests and could also help doctors monitor patients' diets without the handicap of inaccurate self-reporting.

“The thing to keep in mind about our study is that the very nature of the design is kind of biasing us against finding anything,” O’Brien said. “That's why it was exciting to find results—we know we were comparing against an imperfect measure.”

Learn More