When it comes to curing disease with food, quackery goes too far. Over the centuries, raw garlic has been touted as a home remedy for everything from chlamydia to the common cold. The Renaissance included cures for the plague Figs soaked in hyssop oil. During the 1918 influenza pandemic, Native Americans Onion wolf or raucous “liquid beef” Meat broth to keep the deadly virus at bay.
Even in modern times, the Internet Questionable culinary treats aboundApple cider vinegar for gonorrhea. Orange juice for malaria. Mint, milk and pineapple for tuberculosis. It all has a way of making real science look like rubbish. Research on Nutrition and Immunity” got him a bit devastated by everything in this article Eat this to cure cancerLydia Lynch, an immunologist and cancer biologist at Harvard University, told me.
But in recent years, plenty of forensic studies have confirmed that our diet can really affect our ability to fight off invaders—down to the precise functioning of individual immune cells. These studies belong to a new subfield of immunology sometimes referred to as immune metabolism. Researchers still have a long way to go before they will be able to confidently recommend specific foods or supplements for colds, flu, STDs, and other infectious diseases. But one day, knowledge of how nutrients fuel disease-fighting could influence the way infections are treated in hospitals, clinics, and perhaps at home—not just with antimicrobials and steroids but with nutritional supplements, metabolic drugs, or whole foods.
Although there have been major breakthroughs in immune metabolism, the concepts behind them have been around for at least as long as quackery. People have known for thousands of years that in the hours after we become ill, our appetite wanes; The body feels heavy and lethargic. We lose our thirst. In the 1980s, vet Benjamin Hart He argued that those changes were a package deal—some of the many pathological behaviors, as he called them, that are evolutionarily linked in all kinds of creatures. The goal, Hart told me recently, is to “help the animal stay in one place and conserve energy”—especially since the body devotes a large portion of its limited resources to fueling a fever that fights off microbes.
The concept of disease-induced anorexia (not to be confused with an eating disorder anorexia nervosa) may seem, at first, like “a bit of an oxymoron,” says Zuri Sullivan, an immunologist at Harvard University. Fighting disease-causing microbes is very expensive — which makes eating less a very counterintuitive option. But researchers have long hypothesized that calorie restriction can serve a strategic purpose: deprivation of some calories. Pathogens of essential nutrients. (Because viruses do not eat for energy, this concept is limited to cell-based organisms such as bacteria, fungi, and parasites.) A team led by Miguel Soares, an immunologist at the Instituto Gulbenkian de Ciencia, in Portugal, Showed recently That this exact scenario may play out with malaria. When the parasites explode from the red blood cells where they multiply, the resulting mist of heme (a molecule that transports oxygen) causes the liver to stop making glucose. Stopping seems to deprive parasites of nutrition, weaken them, and calm The worst effects of infection.
Reducing sugar can be a dangerous race to the bottom: Animals that give up food while they’re sick try to starve the invaders out before they do. themselves Running out of energy. Let the interruption of glucose extend for too long, and a person dieting could develop dangerously low blood sugar—a common complication of severe malaria—which, if not treated, can become fatal. At the same time, however, the lack of glucose may have beneficial effects on individual tissues and cells during some immune battles. For example, low carb, high fat Keto diet It appears to boost the protective powers of certain types of immune cells in mice, making it more difficult for pathogens to infiltrate airway tissues.
These results are still far from potential human applications. But Andrew Wang, an immunologist and rheumatologist at Yale University, is hopeful that this kind of research could one day lead to better results. Clinical treatments For sepsis, an often fatal condition in which the infection spreads throughout the body and seeps into the blood. “It is still not understood exactly what you should feed people with sepsis,” Li Wang said. He and his former mentor at Yale University, Ruslan Medzhetov, are now conducting a clinical trial to see if changing the balance of carbohydrates and fats in their diet speeds recovery in people with sepsis. If the team is able to detect clear patterns, doctors may eventually be able to flip the body’s metabolic switches with precise doses of drugs, giving immune cells an even greater advantage against their enemies.
But the rules for these food-disease interactions are, as far as anyone understands them, devilishly complex. Sepsis can be caused by a large number of different pathogens. And context really matters. In 2016, Wang, Midgetoff, and colleagues Discover Feeding mice with glucose during infection Starkly different effects Depending on the nature of the pathogen that drives the disease. When mice were infused with glucose, they were infected with the bacteria ListeriaThey all died—while about half of the rodents allowed to succumb to anorexia caused by the infection lived. Meanwhile, the same sugary menu increased the survival rates of mice infected with influenza.
In this case, the difference doesn’t seem to boil down to file size microbe was eating. Instead, the mice’s diet changed the nature of the immune response it was able to regulate – and the amount of collateral damage that response was capable of inflicting on the body, as James Hamblin did. wrote to Atlantic Ocean in time. The type of inflammation triggered by mice ListeriaThe team found that it can endanger fragile brain cells when the rodents are well fed. But when the mice steered clear of sugar, their hungry livers began producing an alternative fuel source called ketone bodies—the same compounds people make when on a ketogenic diet—that helped fuel their nerve cells. Even when the mice were fighting off bacterial infections, their brains remained resistant to the inflammatory burn. The opposite happened when the researchers succumbed to influenza, a virus that causes a different kind of inflammation: glucose prompted brain cells to better protect themselves against the immune system’s fiery response.
There is not yet one unifying principle to explain these differences. But it’s a reminder of an underappreciated side of immunity. Surviving illness, after all, isn’t just about cleansing the body of pathogens; Our tissues must protect themselves from the shrapnel as immune cells and microbes wage all-out war. It is now clear, Soares tells me, that “metabolic reprogramming is a big component of this protection.” Tactics that thwart like bacteria Listeria It also may not protect us from a virus, parasite, or fungus; It may not be ideal in times of peace. Which means our bodies must constantly switch between states of metabolism.
In the same way that potential infections matter, specific types of nutrients also matter: animal fats, vegetable fats, starches, simple sugars, and proteins. Like glucose, fats can be beneficial in some contexts but harmful in others, Lynch found. In people with obesity or other metabolic conditions, immune cells seem to reconfigure themselves to rely more heavily on fats as they carry out their daily functions. They can be much slower when attacking. This is the situation As for a class of cells called natural killers: “They still recognize a cancer or virus-infected cell and go at it as something to kill,” Lynch told me. “But they lacked the energy to actually kill him.” Timing almost certainly matters. The immune defenses that help someone clear the virus in the first few days of infection may not be ideal defenses later in the course of the disease.
Even starving bacterial enemies isn’t a surefire strategy. A few years ago, Janelle Ayres, an immunologist at the Salk Institute for Biological Studies, and her colleagues found that when they infected mice with salmonella And not allowing the rodents to eat, hungry microbes started in their bowels It spreads outside the intestineMost likely in search of food. The migration ended up killing tons of their small mammal hosts. Meanwhile, the mice that were eating normally fared much better — though salmonella Inside it was also easier to send to new hosts. The microbes were also responding to the metabolic environment and trying to adapt. “It would be nice if it was as simple as, ‘If you have a bacterial infection, reduce glucose,’” Ayres said. “But I guess we don’t know.”
All of this leaves immune metabolism in a somewhat chaotic state. “We don’t have simple recommendations” about how to eat your way to improve immunity, Midgetoff told me. Whatever turns up in the end is likely to be modified by warnings: Factors like age, gender, infection, vaccination history, underlying medical conditions, and more can all alter people’s metabolic needs. After Medgetoff’s 2016 study on glucose and viral infections was published, he remembers being dismayed by an article from a foreign outlet circulating online claiming that “a scientist from the US says that during the flu, you should eat candy,” he tells me with a sigh. “That was bad.”
But given how individualistic and messy nutrition can be for humans, it should come as no surprise that the nutritional principles that govern our individual cells can also become quite complex. For now, we might be able to follow our instincts, Midgetoff said. After all, our bodies have been navigating this mess for thousands of years, and you may have picked up some sense of what they need along the way. It may not be a coincidence that during a viral infection, “something sweet like honey and tea can feel really good,” Medgetoff said. There may be some immunomodulatory value in downing classic chicken soup for sick days: It’s full of fluids and salts, useful things to ingest when the body’s electrolyte balance is thrown off by illness.
The science around cravings is still far from resolved. However, Sullivan, who trained with Midgetoff, jokes that she now feels better indulging in a Talenty Mango sherbet when she feels under the weather with something viral, thanks to her colleagues’ 2016 discoveries. Perhaps the sugar helps her body fight off the virus without harming itself. Then again, maybe not. For now, you think it can’t hurt to dig.