Can You Eat Your Way to Better Immunity?

Turmeric and vitamin C boosters recently joined hand sanitiser in the category of hyper-popular products. In the search for any and every type of armour to feel their best, people are stocking up on superfoods and supplements. But to what avail? Can your diet really lead to a stronger immune system?

Quick biology refresher: Your immune system is a complex network of cells and proteins that serves as your body's first (and best) line of defence against harmful viruses and bacteria. To strengthen it, you want to focus on other areas of wellness—in this case, nutrition—that directly affect the network.

Why does what you eat matter? In addition to macronutrients, like protein, your immune system needs sufficient levels of crucial micronutrients, as they work together to sound the alarms and fend off an invader immediately. But relying on high doses of just one micronutrient (say, vitamin C) isn't enough to protect you, says Adrian Gombart, PhD, a professor of biochemistry and biophysics at the Linus Pauling Institute at Oregon State University, who studies immunity. That's because you need a range of strengths within your army, not just a single hero—which means diversifying your diet.

The good news is that doing so is a lot simpler than it sounds. It all comes down to loading up on nutrient-dense foods and getting the recommended intake of vitamins and minerals, without driving yourself crazy (stress can weaken your immunity) or falling for fads (which often forbid helpful food groups). Here's how.

Instead of scooping up every "booster" your local health food spot offers, focus on these four expert-recommended micronutrients:

1. Vitamin D
   "This fat-soluble vitamin is like the head coach that tells every cell in your body what to do and how to behave, including the immune cells that attack invaders", says Roberta Anding, RD, a sports dietitian for the Baylor College of Medicine. "And two-thirds of Americans are deficient".
   
   You should aim for 2,000 IUs a day. You can get the vitamin from the sun (experts say you want 10 to 15 minutes of midday rays several times per week to tick the box without risking skin damage), as well as fatty fish (which also has immunity-boosting omega-3s), certain kinds of mushrooms and egg yolks. Still, most experts suggest taking a supplement to make sure you're truly getting enough.
   
2. Magnesium
   "We know that magnesium, found in leafy green vegetables, can help modulate inflammation and support a healthy immune system", says Taylor Wallace, PhD, a nutrition professor at George Mason University. About half of Americans come up short, says Wallace. And upping your intake could have benefits even if your levels are only slightly low. The government recommends 320 and 420 milligrams per day for adult women and men, respectively. Get it from bulgur (230 milligrams per cup), spinach (157 milligrams per cup) and nuts (almonds have approx. 2.6 milligrams per gram, and cashews have approx. 2.8).
   
3. Vitamin C
   This antioxidant has been shown to stimulate the production of white blood cells, the little guys on the front line of attack. "Frozen berries are great because they're frozen at peak ripeness for max nutrition", says Wallace. The US National Institutes of Health (NIH) suggests 75 milligrams of vitamin C daily for women and 90 milligrams for men. For context, a cup of strawberries has 85 milligrams, a kiwi has 64 and a glass of freshly squeezed OJ has about 90.
   
   If you're particularly nervous about getting sick, Gombart says it's okay to down more C. Extra (around 1,000 to 2,000 milligrams total) is handy if you need to enter fight mode at a moment's notice. And if you don't, you'll just pee out the excess anyway.
   
4. Zinc
   A zinc deficiency can hurt the development of T and B cells, says Ryan Maciel, RD, the head performance-nutrition coach at Precision Nutrition. These are the soldiers mainly responsible for spotting intruders, so you want them to be strong. A review in the "Journal of Immunology Research" found that proper zinc levels can also help fix chronic dysfunctional inflammatory responses. To get more Z—the NIH recommends 8 milligrams daily for women and 11 milligrams for men—prioritise whole grains, beans and seafood, particularly oysters and scallops.

What you don't take in is as important as what you do. Minimise these immunity busters for maximum defence.

1. Alcohol
   While it may be tempting to shake up a random Tuesday cocktail during stressful times, know that alcohol may weaken the respiratory system's defences, even for those who aren't chronically heavy drinkers, according to a study in "Alcohol Research: Current Reviews". An occasional drink or two is fine (if you're of legal age, of course), but try to avoid daily pours and full-on benders.
   
2. Junk food
   A little dessert or a bag of crisps, even if you're splurging more than usual, typically won't invite issues. But that's as long as you're consistently eating wholesome, nutrient-dense foods, like the good stuff mentioned earlier. "A diet high in saturated fat and low in fibre, fruits and vegetables can cause an inflammatory response that may compromise immunity", says Anding.
   
3. Trendy, restrictive diets
   If staying healthy is your main priority, you don't want to cut out food groups. Some immune cells need glucose to function, so skimping on carbs, for example, isn't in your best interests.

There's no harm in tapping into anti-inflammatory "superfoods", like turmeric and ginger. But it's important to make sure your diet is well rounded versus forming a false sense of security from any one ingredient or supplement, says Wallace. Think of it this way: You wouldn't wear a mask in public but neglect to wash your hands once you get home.

If you're worried you're still coming up short on the nutrition front, feel free to pop a multivitamin, says Gombart. Real food is always better, but a little extra armour never hurt anyone.