Precision nutrition: What this new field is trying to accomplish, and why current technology could hold us back

The National Institutes of Health earlier this year unveiled its first-ever, institution-wide plan for nutrition research over the next decade, which includes a strong focus on the field of "precision nutrition." In 2019, the US government invested $1.9 billion into nutrition research.

But some researchers are concerned our current technology may not be sophisticated enough to find the answers we're looking for in the growing field of precision nutrition.

So, what is precision nutrition anyway, and why is the government investing so heavily in its promise?

"Precision nutrition is an approach to developing more targeted and effective diet interventions based on an individual's personal characteristics," said National Institutes of Health Director Dr. Francis Collins, referencing a paper he published this month in the Journal of the American Medical Association.

In other words, precision nutrition is an attempt to answer the question, "What should I eat to stay healthy?" Researchers analyze everything they can about you -- your race, weight, genetics, gender, lifestyle, and more -- to try to come up with a meal plan to help curb disease.

The concept of "precision" nutrition is important because every person is unique, Dr. Kevin Hall, senior investigator at the NIH's National Institute of Diabetes and Digestive and Kidney Diseases, told ABC News.

"People may respond differently to foods and nutrients and therefore, a diet that is best for one person may be quite different from that of another," Hall said.

For instance, some patients may experience a substantial drop in their blood pressure when they limit their salt intake, while others' blood pressure readings respond much more tepidly to a low-salt diet.

And then there's the microbiome -- the billions of bacteria that live inside our gut -- which researchers are now realizing may play a huge role in our health and overall well-being.

Some researchers believe that certain foods may be broken down and absorbed differently in the gut based on the unique composition of bacteria living within each of us. These differences in how our bodies process food, if substantial enough, could lead to different dietary recommendations for different people with different microbiomes.

Several commercial companies even offer at-home testing kits for your microbiome. You provide a stool sample, and the company does the rest, identifying -- sometimes based on limited science -- which foods they think you should and should not eat.

Recently, researchers in precision nutrition have been interested in how individuals respond to dietary carbohydrates, like sugars and starches. For some, eating a granola bar could spike their blood sugar harmfully high, while the same snack might only moderately raise blood sugar in others.

But Hall cautions that proponents of precision nutrition need to ask themselves if we should really be making important medical decisions using this new and evolving field of medicine, where there's still so much left to learn.

Specifically, Hall says, the technologies that we're using to monitor things like blood sugar, the microbiome, and other individual features of our biology may not yet be ready for primetime.

In his most recent paper in The American Journal of Clinical Nutrition, Hall and his colleagues studied two types of continuous glucose monitors. These monitors are little devices placed on the belly or the arm that measure your sugar levels constantly, 24/7. They are a relatively new technology and a huge benefit for patients with diabetes who are sick of pricking their fingers so often.

In the study, Hall and his colleagues equipped participants with these continuous glucose monitors and then fed them standardized meals. They expected that the monitors would correlate, meaning the estimated blood sugar level that each device reported would be roughly the same.

This would be useful data; you could tell some folks not to eat the bagel and cream cheese with turkey bacon because that spiked their blood sugar too high and that they should instead stick with, say, the berry and walnut quinoa cereal. For others, maybe the cereal spiked their blood sugar too high, and they should steer clear.

What the researchers found, however, is that the monitors didn't always correlate. In some participants, one monitor said the bagel was better, and the other monitor said the cereal was better. With such different results, Hall wonders aloud how we would be able to offer dietary advice in line with the tenets of precision nutrition.

"More research is needed to fully understand the reasons for such discrepancies and the implications for precision nutrition," Hall said.

This call for more research couldn't come at a better time, as the nation bears down against the worst pandemic in over a century. We know that poor diet is associated with chronic health conditions like obesity, diabetes and heart disease.

Therefore, according to Collins, "Nutrition research ... is especially important now, in light of the current COVID-19 pandemic, given the increased risks faced by people with these underlying diet-related diseases."

For now, however, what still remains to be seen is how the burgeoning field of precision nutrition will address the question of, "What should I eat?" and if our current technology has the capability of providing answers.

Nate Wood, M.D., is an internal medicine/primary care resident at Yale New Haven Hospital and a contributor to the ABC News Medical Unit.