8 Supplements Dietitians Recommend to Boost Immunity

Oct 31, 2024

For some, cold and flu season means loading up on "immunity-boosting" supplements and remedies. While some people take supplements by the handful, nutrition experts tend to keep only a few key options in their medicine cabinets during the chillier months.

Since supplements are largely unregulated in the United States, non-food remedies that claim to prevent the flu or keep you healthy may overpromise and underdeliver. Yet supplement sales continue to climb, with revenue from vitamin and nutritional supplement production reaching nearly 31 billion dollars in the United States in 2018.

So, which supplements are worth the investment? While remaining mindful of each person's unique nutritional needs and requirements, we asked registered dietitians what they keep stocked in their homes during cold and flu season.

Dietitians are all about evidence-based recommendations, so taking a virtual peek into their medicine cabinet is worthwhile. Just get the green light from your healthcare provider before you start any supplementation plan.

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One vitamin seemingly popular among the registered dietitian community is vitamin D. "Supplementation of vitamin D is critical to help ward off infections," Brittany Scanniello, RD, a Colorado-based registered dietitian, tells Verywell. In addition to assisting with calcium absorption and bone health, vitamin D's role "includes effects on cell proliferation as well as immune-supporting effects," she says.

Melissa Azzarro, RD, a New Hampshire-based registered dietitian and author of A Balanced Approach To PCOS, also takes vitamin D during the cold and flu season.

"Since I am indoors more often, my body is not making this important vitamin from sun exposure," Azzarro tells Verywell, adding that adequate vitamin D levels support a healthy and functioning immune system.

Along with vitamin D, Azzarro keeps additional vitamin C on hand during cold and flu season. "Although additional supplementation of this vitamin won't help me prevent getting sick, it has been shown to help reduce the duration of a cold," she explains. Once a cold sets in, she pops a vitamin C along with her daily supplementation plan.

Whenever she feels under the weather, Azzaro turns to zinc lozenges. “If taken within the first day of illness, this supplement may reduce the duration of illness in some people,” she says. However, she cautions against taking zinc supplements daily along with a multivitamin, as multivitamins often already provide adequate amounts of this mineral.

While not technically a supplement, green tea is a staple in the home of Melissa Nieves, LND, RD, MPH, a registered dietitian and owner of FadFreeNutrition.com.

"Green tea is a great source of antioxidants that help keep the immune system healthy and help ward off flu viruses," Nieves tells Verywell. She says some of the ways tea catechins and polyphenols are thought to help impede influenza viral replication include:

Scanniello says while she loves garlic as an immune-supporting food, eating it daily is unrealistic. "Since a compound found in garlic has been shown to support the disease-fighting response of some white blood cells in the body when fighting a cold or the flu, I like to make sure that my body is fueled up when we enter cold and flu season," she says. "An allicin-containing garlic supplement has its place in my regimen from October through April."

Another supplement found in Azzarro’s home during the colder months is elderberry. However, she only takes it once she feels the onset of illness. “Since the data suggests that taking elderberry can reduce flu symptoms, I am all about it,” Azzarro says.

Probiotics, or live and active bacteria, are a wellness go-to for Whitney Gingerich, MA, RD, an Indiana-based registered dietitian. She takes probiotics consistently during cold and flu season. Certain strains of probiotics offer therapeutic potential for viral infection.

From coffee to candies, there is no shortage of medicinal mushroom products on the market. Scanniello incorporates these into her diet, especially during the winter season.

"Medicinal mushrooms have been shown to impact our immune systems positively," Scanniello says. "They can help keep our immune system balanced—stimulating it when there is something to fight. I often aim for medicinal mushroom 'blends' as each has its own benefit and immunomodulating effects."

Scanniello adds a blend of Chaga, Turkey tail, reishi, maitake, lions mane, cordyceps, and shiitake via powder to her daily smoothie. "All of these have been shown to have immune-balancing effects and are full of antioxidants," she says.

Knowing what registered dietitians are taking to help keep themselves healthy may help guide you on your supplement selection. Just ensure your healthcare provider approves any supplementation plan before you start.

Statista. U.S. sales of vitamins and nutritional supplements manufacturing 2018-2019.

Yan F, Polk D. Probiotics and immune health. Curr Open Gastroenterol. 2011 Oct;27(6):496-501. doi:10.1097/MOG.0b013e32834baa4d

By Lauren Manaker MS, RDN, LD, CLECManaker is a registered dietitian, lactation counselor, and author. She was named an emerging leader in women's health by the National Academy of Nutrition and Dietetics.