Why Protein Is Key to a Healthy Immune System and How Much You Really Need

When you think about the foods that help keep your immune system healthy, vitamin C and zinc may first come to mind. While those are surely health-boosters in their own right, protein is a key ingredient for keeping the immune system in tip-top shape.

"Proteins are the building blocks for all sorts of cells and tissues in the human body, and the immune system is completely included in that," Cynthia Li, MD, integrative and functional medicine doctor and author of ‌Brave New Medicine‌, tells LIVESTRONG.com.

Another way to think about it? "Protein helps to form the cells that operate the immune system," says Isabel Smith, RD, CDN, a New York City-based registered dietitian.

Myb protein, specifically — which can be found in both animals and plants — plays a critical part in keeping our immune system humming along and preventing the development of immune and inflammatory diseases, according to a January 2017 study published in the journal ‌Immunity‌.

When we don't consume enough protein, a lot of important health functions can go downhill, per a November 2012 review article in the ‌Journal of Obesity & Weight Loss Therapy‌. Many of the jobs of the immune system — including preventing sickness and speeding recovery — can be compromised when we get too little of the nutrient.

The recommended dietary intake (RDI) of protein is approximately 46 grams a day for the average woman and 56 grams for the average man, according to Harvard Health Publishing.

These recommendations are based on a formula: 0.8 grams of protein per kilogram of body weight (or 0.36 grams per pound), so you can calculate your personal RDI based on your specific weight.

Research shows that Americans are meeting, if not exceeding, the general guidelines for protein intake. Indeed, a review published December 2019 in ‌Advances in Nutrition‌ found that adults are eating an average of 1.1 grams of protein per kilogram of body weight each day.

Still, ideal protein intake varies from person to person, and some groups of people need more than the average RDI.

If you're working to lose weight, for example, you may actually want to consume ‌more‌ protein than if you were maintaining your weight.

While cutting calories is one reliable way to shed pounds, the same December 2019 study mentioned above revealed that these calories should not come from protein.

In fact, the study reported that those who are actively cutting calories to lose weight should be consuming more — around 1.3 grams of protein per kilogram of body weight (1 kilogram is about 2.2 pounds, for reference).

To put that into perspective, that's about 89 grams of protein for a 150-pound person and 106 grams for a 180-pound person.

One reason this may be? Protein can be helpful for weight loss; it helps you feel full, increases satiety hormones and requires more energy to metabolize, per an April 2015 paper published in the ‌The American Journal of Clinical Nutrition‌.

Similarly, people who are strength-training to build muscle mass may want to increase their protein intake.

A broad sports nutrition review published June 2017 in the ‌Journal of the International Society of Sports Nutrition‌ found that those actively working to build muscle should, at minimum, eat about 1.6 grams of protein per kilogram of body weight each day (or 109 grams for a 150-pound person; 131 grams for a 180-pound person).

Our protein needs shift as we age, and older adults should be especially conscience of getting enough.

According to a position paper published by an international study group in August 2013 in ‌The Journal of Post-Acute and Long-Term Care Medicine‌, healthy adults aged 65 and older should consume 1 to 1.2 grams of protein per kilogram of body weight daily (that's 69 to 81 grams for a 150-pound person, and 81 to 98 grams for a 180-pound person, for reference).

And those who are ill should aim for even more — 1.2 to 1.5 grams per kilogram daily (or up to 102 and 123 grams, respectively).

The reason, the authors explain, is in part because more protein is needed to offset inflammatory conditions associated with chronic and acute diseases that commonly occur with aging. Higher protein intake supports good health and promotes recovery from illness.

There are many delicious, protein-packed foods available to help you meet your nutrition goals and maintain a healthy immune system.

"It's always ideal to get protein from whole foods as opposed to processed foods," Dr. Li says, adding that she'd rather the majority of her patients rely on foods like fatty fish and legumes for protein rather than, say, a protein shake.

Part of her reasoning, she says, is that whole foods are often "naturally packaged with nutrients" that work well together and that our bodies utilize well.

She recommends a variety of foods to keep protein levels in check, including:

• Nuts like almonds and walnuts
• Seeds like chia and flaxseeds
• Legumes like chickpeas, lentils and beans

• Oily fish like wild salmon and sardines
• Eggs
• Organ meats like liver

That said, Dr. Li acknowledges that some people's digestive systems have difficulty processing certain foods (looking at you, beans), who may benefit from more concentrated, processed forms of protein, like whey.

She's also a big fan of bone broth, which she notes is different than meat stock. "It's a broth that's made by cooking bones over a long period of time, with a little bit of vinegar for acid," she explains. "In theory, you're drawing out amino acids, which can be healing for the system."

Smith agrees that both plant- and animal-based proteins can be beneficial for the immune system. "It's just about getting enough," she says, noting that she herself likes to include a mixture of both in her diet. Some favorites? Tofu, edamame, grains, beans, chicken, fish, eggs and dairy.