Personalized nutrition apps could provide valuable data to people trying to eat healthier, though more research must be done to show effectiveness.
As a type 2 diabetic, Michael Snyder has long been interested in how blood sugar levels vary from one person to another in response to the same food, and whether a more personalized approach to nutrition could help tackle the rapidly cascading levels of diabetes and obesity in much of the western world.
Eight years ago, Snyder, who directs the Center for Genomics and Personalized Medicine at Stanford University, decided to put his theories to the test. In the 2000s continuous glucose monitoring, or CGM, had begun to revolutionize the lives of diabetics, both type 1 and type 2. Using spherical sensors which sit on the upper arm or abdomen – with tiny wires that pierce the skin – the technology allowed patients to gain real-time updates on their blood sugar levels, transmitted directly to their phone.
It gave Snyder an idea for his research at Stanford. Applying the same technology to a group of apparently healthy people, and looking for ‘spikes’ or sudden surges in blood sugar known as hyperglycemia, could provide a means of observing how their bodies reacted to an array of foods.
“We discovered that different foods spike people differently,” he says. “Some people spike to pasta, others to bread, others to bananas, and so on. It’s very personalized and our feeling was that building programs around these devices could be extremely powerful for better managing people’s glucose.”
Unbeknown to Snyder at the time, thousands of miles away, a group of Israeli scientists at the Weizmann Institute of Science were doing exactly the same experiments. In 2015, they published a landmark paper which used CGM to track the blood sugar levels of 800 people over several days, showing that the biological response to identical foods can vary wildly. Like Snyder, they theorized that giving people a greater understanding of their own glucose responses, so they spend more time in the normal range, may reduce the prevalence of type 2 diabetes.
The commercial potential of such apps is clear, but the underlying science continues to generate intriguing findings.
“At the moment 33 percent of the U.S. population is pre-diabetic, and 70 percent of those pre-diabetics will become diabetic,” says Snyder. “Those numbers are going up, so it’s pretty clear we need to do something about it.”
Fast forward to 2022,and both teams have converted their ideas into subscription-based dietary apps which use artificial intelligence to offer data-informed nutritional and lifestyle recommendations. Snyder’s spinoff, January AI, combines CGM information with heart rate, sleep, and activity data to advise on foods to avoid and the best times to exercise. DayTwo–a start-up which utilizes the findings of Weizmann Institute of Science–obtains microbiome information by sequencing stool samples, and combines this with blood glucose data to rate ‘good’ and ‘bad’ foods for a particular person.
“CGMs can be used to devise personalized diets,” says Eran Elinav, an immunology professor and microbiota researcher at the Weizmann Institute of Science in addition to serving as a scientific consultant for DayTwo. “However, this process can be cumbersome. Therefore, in our lab we created an algorithm, based on data acquired from a big cohort of people, which can accurately predict post-meal glucose responses on a personal basis.”
The commercial potential of such apps is clear. DayTwo, who market their product to corporate employers and health insurers rather than individual consumers, recently raised $37 million in funding. But the underlying science continues to generate intriguing findings.
Last year, Elinav and colleagues published a study on 225 individuals with pre-diabetes which found that they achieved better blood sugar control when they followed a personalized diet based on DayTwo’s recommendations, compared to a Mediterranean diet. The journal Cell just released a new paper from Snyder’s group which shows that different types of fibre benefit people in different ways.
“The idea is you hear different fibres are good for you,” says Snyder. “But if you look at fibres they’re all over the map—it’s like saying all animals are the same. The responses are very individual. For a lot of people [a type of fibre called] arabinoxylan clearly reduced cholesterol while the fibre inulin had no effect. But in some people, it was the complete opposite.”
Eight years ago, Stanford's Michael Snyder began studying how continuous glucose monitors could be used by patients to gain real-time updates on their blood sugar levels, transmitted directly to their phone.
The Snyder Lab, Stanford Medicine
Because of studies like these, interest in precision nutrition approaches has exploded in recent years. In January, the National Institutes of Health announced that they are spending $170 million on a five year, multi-center initiative which aims to develop algorithms based on a whole range of data sources from blood sugar to sleep, exercise, stress, microbiome and even genomic information which can help predict which diets are most suitable for a particular individual.
“There's so many different factors which influence what you put into your mouth but also what happens to different types of nutrients and how that ultimately affects your health, which means you can’t have a one-size-fits-all set of nutritional guidelines for everyone,” says Bruce Y. Lee, professor of health policy and management at the City University of New York Graduate School of Public Health.
With the falling costs of genomic sequencing, other precision nutrition clinical trials are choosing to look at whether our genomes alone can yield key information about what our diets should look like, an emerging field of research known as nutrigenomics.
The ASPIRE-DNA clinical trial at Imperial College London is aiming to see whether particular genetic variants can be used to classify individuals into two groups, those who are more glucose sensitive to fat and those who are more sensitive to carbohydrates. By following a tailored diet based on these sensitivities, the trial aims to see whether it can prevent people with pre-diabetes from developing the disease.
But while much hope is riding on these trials, even precision nutrition advocates caution that the field remains in the very earliest of stages. Lars-Oliver Klotz, professor of nutrigenomics at Friedrich-Schiller-University in Jena, Germany, says that while the overall goal is to identify means of avoiding nutrition-related diseases, genomic data alone is unlikely to be sufficient to prevent obesity and type 2 diabetes.
“Genome data is rather simple to acquire these days as sequencing techniques have dramatically advanced in recent years,” he says. “However, the predictive value of just genome sequencing is too low in the case of obesity and prediabetes.”
Others say that while genomic data can yield useful information in terms of how different people metabolize different types of fat and specific nutrients such as B vitamins, there is a need for more research before it can be utilized in an algorithm for making dietary recommendations.
“I think it’s a little early,” says Eileen Gibney, a professor at University College Dublin. “We’ve identified a limited number of gene-nutrient interactions so far, but we need more randomized control trials of people with different genetic profiles on the same diet, to see whether they respond differently, and if that can be explained by their genetic differences.”
Some start-ups have already come unstuck for promising too much, or pushing recommendations which are not based on scientifically rigorous trials. The world of precision nutrition apps was dubbed a ‘Wild West’ by some commentators after the founders of uBiome – a start-up which offered nutritional recommendations based on information obtained from sequencing stool samples –were charged with fraud last year. The weight-loss app Noom, which was valued at $3.7 billion in May 2021, has been criticized on Twitter by a number of users who claimed that its recommendations have led to them developed eating disorders.
With precision nutrition apps marketing their technology at healthy individuals, question marks have also been raised about the value which can be gained through non-diabetics monitoring their blood sugar through CGM. While some small studies have found that wearing a CGM can make overweight or obese individuals more motivated to exercise, there is still a lack of conclusive evidence showing that this translates to improved health.
However, independent researchers remain intrigued by the technology, and say that the wealth of data generated through such apps could be used to help further stratify the different types of people who become at risk of developing type 2 diabetes.
“CGM not only enables a longer sampling time for capturing glucose levels, but will also capture lifestyle factors,” says Robert Wagner, a diabetes researcher at University Hospital Düsseldorf. “It is probable that it can be used to identify many clusters of prediabetic metabolism and predict the risk of diabetes and its complications, but maybe also specific cardiometabolic risk constellations. However, we still don’t know which forms of diabetes can be prevented by such approaches and how feasible and long-lasting such self-feedback dietary modifications are.”
Snyder himself has now been wearing a CGM for eight years, and he credits the insights it provides with helping him to manage his own diabetes. “My CGM still gives me novel insights into what foods and behaviors affect my glucose levels,” he says.
He is now looking to run clinical trials with his group at Stanford to see whether following a precision nutrition approach based on CGM and microbiome data, combined with other health information, can be used to reverse signs of pre-diabetes. If it proves successful, January AI may look to incorporate microbiome data in future.
“Ultimately, what I want to do is be able take people’s poop samples, maybe a blood draw, and say, ‘Alright, based on these parameters, this is what I think is going to spike you,’ and then have a CGM to test that out,” he says. “Getting very predictive about this, so right from the get go, you can have people better manage their health and then use the glucose monitor to help follow that.”
Electricity is emerging as a powerful treatment for chronic ailments.
Kelly, a case manager for an insurance company, spent years battling both migraines and Crohn's, a disease in which the immune system attacks the intestines.
For many people, like Kelly, a stronger electric boost to the vagus nerve could be life-changing.
After she had her large intestine removed, her body couldn't absorb migraine medication. Last year, about twice a month, she endured migraines so bad she couldn't function. "It would go up to a ten, and I would rock, wait it out," she said. The pain might last for three days.
Then her neurologist showed her a new device, gammaCore, that tames migraines by stimulating a nerve—not medication. "I don't have to put a chemical in my body," she said. "I was thrilled."
At first, Kelly used the device at the onset of a migraine, applying electricity to her pulse at the front of her neck for six minutes. The pain peaked at about half the usual intensity--low enough, she said, that she could go to work. Four months ago, she began using the device for two minutes each night as prevention, and she hasn't had a serious migraine since.
The Department of Defense and Veterans Administration now offer gammaCore to patients, but it hasn't yet been approved by Medicare, Medicaid, or most insurers. A month of therapy costs $600 before insurance or a generous financial assistance program kicks in.
A patient uses gammaCore, a non invasive vagal nerve stimulator device that was FDA approved in November 2018, to treat her migraine.
(Photo captured from a patient video at gammacore.com)
If the poet Walt Whitman wrote "I Sing The Body Electric" today, he might get specific and point to the vagus nerve, a bundle of fibers that run from the brainstem down the neck to the heart and gut. Singing stimulates it—and for many people, like Kelly, a stronger electric boost to the nerve could be life-changing.
The mind-body connection isn't just an idea — the vagus nerve literally carries signals from the mind to the body and back. It may explain the link between childhood trauma and illnesses such as chronic pain and headaches in adults. "How is it possible that a psychological event causes pain years later?" asked Peter Staats, co-founder of electroCore, which has won approval for its new device from the Food and Drug Administration (FDA) for both migraine and cluster headaches. "There has to be a mind-body interface, and that is the vagus nerve," he said.
Scientists knew that this nerve controlled your heart rate and blood pressure, but in the past decade it has been linked to both pain and the immune system.
"Everything is gated through the vagus -- problems with the gut, the heart, and the lungs," said Chris Wilson, a researcher at Loma Linda University, in California. Wilson is studying how vagus nerve stimulation (VNS) could help pre-term babies who develop lung infections. "Nearly every one of our chronic diseases, including cancer, Alzheimer's, Parkinson's, chronic arthritis and rheumatoid arthritis, and depression and chronic pain…could benefit from an appropriate stimulator," he said.
It's unfortunate that Kelly got her device only after her large intestine was gone. SetPoint Medical, a privately held California company founded to develop electronic treatments for chronic autoimmune diseases, has announced early positive results with VNS for both Crohn's and rheumatoid arthritis.
As SetPoint's chief medical officer, David Chernoff, put it, "We're hacking into the nervous system to activate a system that is already there," an approach that, he said, could work "on many diseases that are pain- and inflammation-based." Inflammation plays a role in much modern illness, including depression and obesity. The FDA already has approved VNS for both, using surgically implanted devices similar to pacemakers. (GammaCore is external.)
The history of VNS implants goes back to 1997, when the FDA approved one for treating epilepsy and researchers noticed that it rapidly lifted depression in epileptic patients. By 2005, the agency had approved an implant for treatment-resistant depression. (Insurance companies declined to reimburse the approach and it didn't take off, but that might change: in February, the Center for Medicare and Medicaid Services asked for more data to evaluate coverage.) In 2015, the FDA approved an implant in the abdomen to regulate appetite signals and help obese people lose weight.
The link to inflammation had emerged a decade earlier, when researchers at the Feinstein Institute for Medical Research, in Manhasset, New York, demonstrated that stimulating the nerve with electricity in rats suppressed the production of cytokines, a signaling protein important in the immune system. The researchers developed a concept of a hard-wired pathway, through the vagus nerve, between the immune and nervous system. That pathway, they argued, regulates inflammation. While other researchers argue that VNS is helpful by other routes, there is clear evidence that, one way or another, it does affect immunity.
At the same time, investors are seeking alternatives to drugs.
The Feinstein rat research concluded that it took only a minute a day of stimulation and tiny amounts of energy to activate an anti-inflammatory reflex. This means you can use devices "the size of a coffee bean," said Chernoff, much less clunky than current pacemakers—and advances in electronic technology are making them possible.
At the same time, investors are seeking alternatives to drugs. "There's been a push back on drug pricing," noted Lisa Rhoads, a managing director at Easton Capital Investment Group, in New York, which supported electroCore, "and so many unintended consequences."
In 2016, the U.S. National Institutes of Health began pumping money into relevant research, in a program called "Stimulating Peripheral Activity to Relieve Conditions," which focuses on "understanding peripheral nerves — nerves that connect the brain and spinal cord to the rest of the body — and how their electrical signals control internal organ function."
GlaxoSmithKline formed Galvani Bioelectronics with Google to study miniature implants. It had already invested in Action Potential Venture Capital, in Cambridge, Massachusetts, which holds SetPoint and seven other companies "that are all targeting a nerve to treat a chronic disease," noted partner Imran Eba. "I see a future in which bioelectronics medicine is competing directly with drugs," he said.
Treating the body with electricity could bring more ease and lower costs. Many people with serious auto-immune disease, for example, have to inject themselves with drugs that cost $60,000 a year. SetPoint's implant would cost less and only need charging once a week, using a charger worn around the neck, Chernoff said. The company receives notices remotely and can monitor compliance.
Implants also allow the treatment to target a nerve precisely, which could be important with Parkinson's, chronic pain, and depression, observed James Cavuoto, editor and publisher of Neurotech Reports. They may also allow for more fine-turning. "In general, the industry is looking for signals, biomarkers that indicate when is the right time to turn on and turn off the stimulation. It could dramatically increase the effectiveness of the therapy and conserve battery life," he said.
Eventually, external devices could receive data from biomarkers as well. "It could be something you wear on your wrist," Cavuoto noted. Bluetooth-enabled devices could communicate with phones or laptops for data capture. External devices don't require surgery and put the patient in charge. "In the future you'll see more customer specification: Give the patient a tablet or phone app that lets them track and modify their parameters, within a range. With digital devices we have an enormous capability to customize therapies and collect data and get feedback that can be fed back to the clinician," Cavuoto said.
Slow deep breathing, the traditional mind-body intervention, is "like watching Little League. What we're doing is Major League."
It's even possible to stimulate the vagus through the ear, where one branch of the bundle of fibers begins. In a fetus, the tissue that becomes the ear is also part of the vagus nerve, and that one bit remains. "It's the same point as the acupuncture point," explained Mark George, a psychiatrist and pioneer researcher in depression at Medical University of South Carolina in Charleston. "Acupuncture figured out years ago by trial and error what we're just learning about now."
Slow deep breathing, the traditional mind-body intervention, also affects the vagus nerve in positive ways, but gently. "That's like watching Little League," Staats, the co-founder of electroCore, said. "What we're doing is Major League."
In ten years, researcher Wilson suggested, you could be wearing "a little ear cuff" that monitors your basic autonomic tone, a heart-attack risk measure governed in part by the vagus nerve. If your tone looked iffy, the stimulator would intervene, he said, "and improve your mood, cognition, and health."
In the meantime, we can take some long slow breaths, read Whitman, and sing.
