8 Supplements Dietitians Are Taking During Cold and Flu Season

supplements in woman's hand

Kathleen Finlay / Getty Images

Key Takeaways

  • Not all "immune-boosting" supplements will help keep you healthy during cold and flu season.
  • The dietitians we spoke with only take certain supplements for immune support, and some are only taken once a cold or the flu sets in.

Cold and flu season is upon us, which for some means loading up on “immunity-boosting” supplements and remedies. While some people take supplements by the handful during this time of the year, nutrition experts tend to only keep a few key options in their medicine cabinet 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 about the different nutritional needs and requirements unique to each person, we asked registered dietitians what they keep stocked in their own homes during cold and flu season.

Dietitians are all about evidence-based recommendations, so it's worthwhile to take a virtual peek into their medicine cabinets. Just make sure to get the green light from your doctor before you start any supplementation plan. 

Vitamin D

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. 

Vitamin C

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.

Zinc Lozenges

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 every day along with a multivitamin, as multivitamins often already provide adequate amounts of this mineral.  

Green Tea

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 

"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:

  • Inhibiting the interaction of a virus with the cell membrane when it invades a cell 
  • Increasing natural killer (NK) cell activity
  • Suppressing viral genome replication and viral protein expression


Scanniello says while she loves garlic as an immune-supporting food, eating it every day is not realistic. “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.

Medicinal Mushrooms

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 in a positive way,” Scanniello says. “They can help keep our immune system in balance—stimulating it when there is something to fight. I often aim for medicinal mushroom 'blends' as each mushroom has its own benefit and its own 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.

What This Means For You

Knowing what registered dietitians are taking to help keep themselves healthy may help guide you on your own supplement selection. Just make sure your doctor approves of any supplementation plan before you start. 

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Statista. U.S. sales of vitamins and nutritional supplements manufacturing 2018-2019. Aug 9, 2019.

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