Changing your diet to improve your health is nothing new—people with diabetes, obesity, Crohn’s disease, celiac disease, food allergies, and a host of other conditions have long done so as part of their treatment. But new and sophisticated knowledge about biochemistry, nutrition, and artificial intelligence has given people more tools to figure out what to eat for good health, leading to a boom in the field of personalized nutrition.
Personalized nutrition, often used interchangeably with the terms precision nutrition or individualized nutrition is an emerging branch of science that uses machine learning and “omics” technologies (genomics, proteomics, and metabolomics) to analyze what people eat and predict how they respond to it. Scientists, nutritionists, and health care professionals take the data, analyze it, and use it for a variety of purposes, including identifying diet and lifestyle interventions to treat disease, promote health, and enhance performance in elite athletes.
Increasingly, it’s being adopted by businesses to sell products and services such as nutritional supplements, apps that use machine learning to provide a nutritional analysis of a meal based on a photograph, and stool-sample tests whose results are used to create customized dietary advice that promises to fight bloat, brain fog, and a myriad of other maladies.
“Nutrition is the single most powerful lever for our health,” says Mike Stroka, CEO of the American Nutrition Association, the professional organization whose mandate includes certifying nutritionists and educating the public about science-based nutrition for health care practice. “Personalized nutrition will be even bigger.”
In 2019, according to ResearchandMarkets.Com, personalized nutrition was a $3.7 billion industry. By 2027, it is expected to be worth $16.6 billion. Among the factors driving that growth are consumer demand, the falling cost of new technologies, a greater ability to provide information, and the increasing body of evidence that there is no such thing as a one-size-fits-all diet.
The sequencing of the human genome, which started in 1990 and concluded 13 years later, paved the way for scientists to more easily and accurately find connections between diet and genetics.
When the term “personalized nutrition” first appeared in the scientific literature, in 1999, the focus was on using computers to help educate people about their dietary needs. It wasn’t until 2004 that scientists began to think about the way genes affect how and what we eat, and how our bodies respond. Take coffee, for instance: Some people metabolize caffeine and the other nutrients in coffee in a productive, healthy way. Others don’t. Which camp you fall into depends on a host of factors including your genetics, age, environment, gender, and lifestyle.
More recently, researchers have been studying connections between the health of the gut microbiome and conditions including Alzheimer’s, Parkinson’s, and depression. The gut microbiome, the body’s least well-known organ, consists of more than 1000 species of bacteria and other microbes. Weighing in at almost a pound, it produces hormones, digests food that the stomach can’t, and sends thousands of different diet-derived chemicals coursing through our bodies every day. In many respects the microbiome is key to understanding nutrition and is the basis of the growth in personalized nutrition.
Blood, urine, DNA, and stool tests are part of the personalized nutrition toolkit that researchers, nutritionists, and health care professionals use to measure the gut microbiome and the chemicals (known as metabolites) it produces. They use that data, sometimes in conjunction with self-reported data collected via surveys or interviews, as the basis for nutrition advice.
Stool sample tests that measure gut microbiome composition and diversity are among the fastest growing sector in the market, along with accompanying products. Companies take the results and use them to provide customized diets and advice designed to improve gut health.
Ruth Cammish, a general physician in Manchester, England, had already changed her diet when she had her stool tested by AtlasBiomed a couple of years ago. Rather than life-changing advice, she was seeking a benchmark of her gut health; she’d recently increased her fiber intake and the diversity of her food choices in a successful attempt to treat the lifelong eczema that had worsened as she neared 40. Now she wanted to know what the changes meant for her microbiome.
The test confirmed that she was on the right track, motivating her to continue eating foods “rich in different colors of the rainbow” and taking probiotics for her skin. She also appreciated the weekly food recommendations that AtlasBiomed sent to her. She’s taken the tests a few more times, more out of curiosity and the opportunity to glean nutritional information than as a curative: She isn’t convinced the results will miraculously fix everything that ails her.
“I take it with a pinch of salt,” she says. “It’s a snapshot of what your microbiome is doing at that moment. The microbiome changes, and these tests are in their infancy.”
If you’re thinking of signing up for a stool sample test, Cammish’s attitude is a healthy one, says Mariette Abrahams, founder and CEO of Qina.Tech, a consulting firm and platform that has been collecting and analyzing data on the business and science of personalized nutrition since 2012, when you could count on one hand the number of companies in the industry.
“When it comes to microbiome tests, the technology is available, but the science is only emerging,” she says. “We are not yet at a point where we can accurately specify or predict what you need to eat to modify your microbiome in the long term.”
One limiting factor is that most areas of digital health research, including the microbiome and nutrigenetics, have focused primarily on northern Europeans and North Americans, the people who tend to make use of the technologies. Studies need to be diverse across populations and the socioeconomic sphere before nutrition can truly be personalized.
Another limitation is that scientists are still struggling to understand what is a healthy microbiome and what is an unhealthy one. “The idea that you can predict what you eat, what the microbes are going to do, and what it’s going to do to you is very appealing but we don’t have enough data yet to do it really well,” says Brett Finlay, a microbiologist at the University of British Columbia.
When Finlay was researching The Whole-Body Microbiome, How to Harness Microbes—Inside and Out—for Lifelong Health, which he co-wrote, he had samples of his stool analyzed by DayTwo, American Gut, and the now-defunct UBiome. He was impressed with the amount of information he received. "If you are a microbiologist geek and love looking at microbe names, they’re fun.” he says.
But with the exception of DayTwo, which gave each food he ate a letter grade (foods now receive a number score on an app), Finlay didn’t receive much in the way of what he calls “actionable items.”
That’s not surprising. Given how new the science is, expecting a microbiome test alone to tell you everything you need to know about what to eat for better health is unrealistic, according to Jonathan Eisen, a UC Davis microbiologist who regularly doles out an “overselling the microbiome award” on his blog.
“Imagine trying to study a tropical rainforest by flying a drone around the outside, chopping up one square foot of the leaves, sucking them out into a vacuum cleaner and flying away, and saying you understand the rainforest,” he says.
Eisen served on the scientific advisory board at UBiome, although he left years before the company was charged with multiple counts of fraud, in part because he was having problems with some of the claims it was making about its products and their clinical utility.
Much of the advice that stool-sample test companies give “is advice that could be given and should be given without ever sampling our microbiome or feces or skin,” he says. “It’s just general advice about fiber and other good nutritional practices.”
There’s a history of overpromising in the tech industry; at the end of August, Theranos founder Elizabeth Holmes is scheduled to go on trial for doing just that. Not every company is a Theranos, but if you’re looking for a cautionary tale, that’s a particularly apt and timely one.
With that in mind, what should consumers look for if, like Cammish, they’re curious? Abrahams says a good place to start is with a company’s website: Look for a credible scientific team that understands the science and technologies.
Learn what technologies the company uses to analyze its samples and provide actionable recommendations. To ensure that your expectations are met, find out what you’ll receive in a report. Some companies offer food lists. Others offer a dashboard.
Think twice before going with a company that wants to sell you a product based on an assessment. “If it is done well and with integrity, it can be better because there is a synergistic approach,” says Stroka of the ANA. “But there is a potential conflict of interest there, that the assessment will be geared toward selling you a product.”
While microbiome tests can identify a large fraction of the trillions of microbes in the gut, Abraham cautions that you may get different results and recommendations depending on what company you use, because different companies use different protocols and have different quality standards. She also advises learning whether the company’s approach has been validated in clinical trials.
Eisen agrees. “You can’t assess what someone is doing if they don’t share their methods and their results,” he says, adding that testimonials on a website are no substitute for research papers about the microbiome that have been published in peer-reviewed journals.
Among the many companies offering stool sample tests, only a small number, such as DayTwo, have those kinds of publications. However, Eisen says, “This does not mean all of DayTwo’s claims are backed up by papers, but rather that at least they have some scientific publications that back up some of what they are doing.”
As skeptical as he is, Eisen remains an optimist. “I think there is no doubt we will be able to do personalized nutrition about the microbiome at some point,” he says, “but I also know that it is just insanely complicated and we can barely figure out what is going on in mice that are inbred and genetically identical to each other and raised on the exact same food source in a lab setting where they are exposed to the same everything. With humans, it’s even more complicated.
“It is an extraordinarily difficult thing to do, even though I want to do it and think it is coming,” he adds. “But it’s not coming as fast as these companies say it is coming.”