The COVID-19 pandemic has consumers charging the immune-health supplements aisle. Stay ahead by formulating with these immunity ingredients.

Todd Runestad, Content Director,

July 6, 2020

11 Min Read
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Insider’s Take

  • While there is no FDA-approved treatment for coronavirus, proven products can help shore up the body’s immunity defenses.

  • Vitamins C and D, probiotics and garlic are among the ingredients with antioxidant and other antiviral properties.

  • Studies have shown that stress leads to higher risk of developing a cold, and that it increases the body’s time to heal.


Supplement makers are reporting record sales, thanks to the global coronavirus pandemic. This is a great opportunity for supplement manufacturers and marketers to take a closer look at the SKUs currently on the market and a fresh look at the innovation pipeline—and quickly formulate new brands for an eager consumer base receptive to anything that might help optimize their health status.

Important note: There is no FDA-approved treatment for the disease in the United States (Gilead’s Remdesivir drug has the agency’s only emergency approval). A vaccine is perhaps 12 months away. Supplement companies making claims that their products can treat the coronavirus are receiving warning letters from FDA.

However, a healthy, functioning immune system can at least help people shore up their body’s defenses. “Pandemic” spells opportunity for responsible supplement makers and the ingredient suppliers that service them.

Among the studied and sought-after ingredients, these seven stand out.

1) Vitamin C

Vitamin C is of course renowned as a water-soluble antioxidant, but it is also vital to the function of white blood cells that help fight infections.

Interestingly, a study published in February 2020—before the coronavirus pandemic really hit—found that vitamin C may shorten the length of time patients spend in intensive care and decrease the duration of time patients need to be on a ventilator by about 14% and up to 25%. Patients in the most critical condition benefited the most—the amount of vitamin C needed to have an effect, according to a meta-analysis, was only 1-6 g/day.1

In China, the United States and other parts of the world, vitamin C is being researched as a potential treatment for the COVID-19 virus. Researchers are giving patients ultra-high-dose intravenous (IV) vitamin C. Oral vitamin C supplements, upon the metabolism and digestion process, get excreted in the urine. And oral doses of above 2,000 mg (2g) can lead to diarrhea, according to the National Institutes of Health (NIH). But intravenous vitamin C gets delivered straight into the bloodstream, where it is believed to exert anti-viral effects. In one study published in April 2020, researchers surmised that vitamin C may reduce inflammation in the lungs, which might be a key area of concern because of the problem of lung injury with COVID-19 patients.2

The dosage recommendation used in China ranges from 50-200 milligrams per kilogram body weight per day. The doses correlate to approximately 4 to 16 grams for an adult, administered via IV.3

2) Vitamin D

Vitamin D deficiency, in observational studies, is associated with increased risk of infections. In particular, those with larger deficiencies tend to have significantly longer and more severe upper respiratory tract infections (URTI).4 One study found best results among those with blood levels of a paltry 10 ng/dl.5

Vitamin D is fat-soluble, which means instead of daily supplementation a person could theoretically take larger doses every few days for the same result. But a meta-analysis of 11 placebo-controlled studies of 5,660 patients found that once-daily dosing was superior to large erratic “bolus” injection doses. Overall, the conclusion is that vitamin D does show a protective effect against URTIs.6

So, how much should a person take? A 2017 Canadian study among children ages 1-5 years old found no real effect with either 400 IU or 2,000 IU/day.7

Yet a study in China found that among infants 1,200 IU/day significantly decreased the incidence and rapid relief from symptoms and disease recovery.8

A study among elderly long-term care patients in Colorado found 100,000 IU a month reduced the incidence of URTIs.9 Yet a different study, also using 100,000 IU/month for 18 months, found no difference.10

Surely there’s a middle ground, no?

Researchers in New Zealand gave pregnant women (start of their third trimester) and their subsequent infants (for the first six months of their lives) either placebo/placebo, 400/1,000 IU, or 800/2,000 IU vitamin D per day. Only the higher doses of vitamin D led to a significant decrease in acute respiratory infections.11

The upshot may be that certainly those with low vitamin D levels can benefit—and it may be that it’s not really the “cold and flu season” but rather the “vitamin D deficiency season.”

3) Colostrum

In 2007, a study was published comparing the flu vaccination against colostrum, a bovine source of the first mother’s milk and used to enhance immune function—newborns need a shot of colostrum to get off to a good start in this rough-and-tumble world full of invisible germs and microbes that can fell a fledgling life form on this planet. After two months of treatment with 400 mg/day colostrum supplements, plus three months of follow-up, the number of days with flu was three times higher in the non-colostrum subjects. 12

Repeat: the number of days with flu was three times higher among those not taking the colostrum.

Among 144 healthy individuals between 30 and 80 years old, the colostrum group had 13 episodes versus 14 in the colostrum plus flu vaccination group, 41 in the group with no flu vaccine, and 57 in subjects who were not treated with anything. Researchers suggested that cytokines in colostrum may stimulate production of protective antibodies that may allow protection against certain viruses.

Another study gave subjects 600 mg of colostrum per day for eight weeks.13 Those taking colostrum experienced a significantly lesser number of upper respiratory tract infection symptoms—colds and flu are considered URTIs—though the duration of symptoms was the same in the colostrum and placebo groups.

4) Probiotics

The above colostrum researchers noted that, in many instances, influenza starts from the intestinal tract. Convenient, because that’s the bull’seye of bacteria both onerous and beneficial—the latter being another term for probiotics.

One meta-analysis of 12 studies involving 3,720 participants of all ages found probiotics were better than placebo when measuring the number of episodes of acute URTIs and the duration of a URTI.14

The problem with this meta-analysis and other studies is a lack of consistently identifying which specific probiotic strains work. There are so many these days.

Two of the most-studied probiotic strains are LGG and BB12. LGG is found in the Culturelle finished product brand (by i-Health, a division of DSM). BB12 is supplied by Chr. Hansen.

One study using LGG on nursing home residents aged 65 and older found 10 billion CFUs of LGG daily for six months led to one-third fewer respiratory viral infections, compared to placebo.15

In a study among college students in dorms, researchers gave 231 students either placebo or 1 billion CFUs of each LGG and BB-12 for 12 weeks.16 The median duration of URTIs was significantly shortened by 2 days and median severity score was 34% lower with the probiotics. The students taking probiotics also missed significantly fewer school days (though not so for workdays, which might demonstrate the incentive of money over learning).

BB12 was also found to be effective in infants. In one study among infants less than 2 months of age until eight months, the infants taking 10 billion CFU of BB12 experienced fewer respiratory infections compared to placebo.17

5) Garlic

Garlic has long been used to help immune function. In modern times researchers have discovered the stinking rose can enhance immune cell function. Research has shown garlic’s ability to reduce the frequency of infections with common cold or influenza pathogens. In one study, researchers randomly assigned 146 participants to either a garlic supplement containing 180 mg of allicin content or a placebo once daily for 12 weeks.18 The garlic group suffered 111 days of illness, versus 366 in the placebo group. The duration of illness was a day less in the garlic group, from about four compared to about five days in the placebo group.18

Another garlic study used 2.56 g/day of aged garlic extract on 60 patients, while another 60 took a placebo.19 After 45 days, there was a significant increase in proliferation of NK cells, which are part of the body’s primary defense against viral infection. After 90 days, the garlic group had 21% lower symptom scores and 76% fewer days with decreased activity, as well as 61% fewer days lost per episode of illness.  

6) Olive leaf extract

Olive leaf extract has only recently come to the scientific fore to assess its role in immunity. Known as antioxidant-rich, olive leaves contain a polyphenolic compound called oleuropein. In 2016, New Zealand researchers gave 20 ml/day olive leaf extract to 29 healthy men for eight weeks.20 They found the group taking the olive leaf extract had a significant response within the type of white blood cells called peripheral blood mononuclear cells, which includes T cells, B cells, NK cells and monocytes. Analysis of genetic behavior showed the olive leaf extract turned on genes responsible for promoting immune balance.  

7) CBD

The body’s immune system is the main barrier in preventing harmful pathogens from entering your body. An easy way to strengthen it is by looking at what you do every day and making some small lifestyle changes. In particular, the big three are washing hands, getting good sleep and keeping stress in check.

Studies show stressed-out people have a higher risk of subsequently developing a cold.21

Other studies have found that stress increases the amount of time it takes the body to heal from wounds.22

With sleep, one study found those dozing for more than seven hours a night were four times less likely to develop a cold than those getting less than six hours of sleep a night.23

Hemp CBD may not be able to get people to wash their hands more often or better, but evidence suggests it could help people with sleep difficulties.24

Early investigations are suggesting that hemp CBD possesses anti-stress properties.25

There are no direct studies yet on hemp CBD vis-à-vis immune function, but it does seem to help with contributing factors to keeping us healthy. A balanced life is a healthy life.


1 Hemila H and Chalker E. “Vitamin C May Reduce the Duration of Mechcanical Ventilation in Critically Ill Patients: A Meta-Regression Analysis.” J Intensive Care. 2020;3:15.

2 Hernandez A et al. “Two Known Therapies Could Be Useful as Adjuvant Therapy in Critical Patients Infected by COVID-19.” Rev Esp Anestesiol Reanim. 2020:S0034-9356(20)30075-X.

3 Shanghai Medical Association. “Shanghai 2019 Expert Coronary Disease Comprehensive Treatment Consensus.”

4 Dubnov-Raz G et al. “Vitamin D Supplementation and Upper Respiratory Tract Infections in Adolscent Swimmers: A Randomized Controlled Trial.” Pediatr Exerc Sci. 2015;27(1):113-119.

5 Martineau AR et al. “Vitamin D Supplementation to Prevent Acute Respiratory Tract Infections: Systematic Review and Meta-Analysis of Individual Participant Data.” BMJ. 2017;356:i6583.

6 Bergman P et al. “Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” PLoS One. 2013;8(6):e65835.

7 Aglipay M et al. “Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy Children.” JAMA. 2017;318(3):245-254.

8 Zhou J et al. “Preventive Effects of Vitamin D on Seasonal Influenza A in Infants: A Multicenter, Randomized, Open, Controlled Clinical Trial.” Pediatr Infect Dis J. 2018;37(8):749-754.

9 Ginde A et al. “High-Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long-Term Care Residents: A Randomized Clinical Trial.” J Am Geriatr Soc. 2017;65(3):496-503.

10 Murdoch DR et al. “Effect of Vitamin D3 Supplementation on Upper Respiratory Tract Infections in Healthy Adults: The VIDARIS Randomzed Controlled Trial.” JAMA. 2012;308(13):1333-1339.

11 Grant CC et al.“Reduced Primary Care Respiratory Infection Visits Following Pregnancy and Infanct Vitamin D Supplementation: A Randomised Controlled Trial.” Acta Paediatr. 2015;104(4):396-404.

12 Cesarone MR et al.“Prevention of Influenza Episodes With Colostrum Compared With Vaccination in Healthy and High-Risk Cardiovascular Subjects: The Epidemiologic Study in San Valentino.” Clin Appl Thrombosis/Hemostasis. 2007;13(2):130-136.

13 Brinkworth GD and Buckley JD. “Concentrated Bovine Colostrum Protein Supplementation Reduces the Incidence of Self-Reported Symptoms of Upper Respiratory Tract Infection in adult Males.” Eur J Nutr. 2003;42:228-232.

14 Hao Q et al. “Probiotics for Preventing Acute Upper Respiratory Tract Infections.” Cochrane Database Syst Rev. 2015;2:CD006895.

15 Wang B et al. “Probiotics to Prevent Respiratory Infections in Nursing Homes: A Pilot Randomized Controlled Trial.” J Am Geriatr Soc. 2018;66(7):1346-1352.

16 Smith TH et al. “Effect of Lactobacillus Rhamnosus LGG and Bifidobacterium Animalis Ssp. Lactis BB-12 on Health-Related Quality of Life in College Students affected by Upper Respiratory Infections.” Br J Nutr. 2013;109(11):1999-2007.

17 Taipale T et al. “Bifidobacterium Animalis Subsp. Lactis BB-12 in Reducing the Risk of Infections in Infancy.” Br Jr Nutr. 2011 Feb;105(3):409-416.

18 Lissiman E et al. “Garlic for the Common Cold.” Cochrane Database Syst Rev. 2014;2014(11):CD006206.

19 Nantz MP et al. “Supplementation with Aged Garlic Extract Improves Both NK and YS-T Cell Function and Reduces the Severity of Cold and Flu Symptoms: A Randomized, Double-Blind, Placebo-Controlled Nutrition Intervention.” Clin Nutr. 2012;31(3):337-344.

20 Boss A et al. “Human Intervention Study to assess the Effects of Supplementation with Olive Leaf Extract on Peripheral Blood Mononuclear Cell Gene Expression.” Int J Mol Sci. 2016;17(12):2019.

21 Cohen S et al. “Chronic Stress, Glucocorticoid Receptor Resistance, Inflammation, and Disease Risk.” PNAS. 2012 Apr 2;201118355.

22 Parker-Pope T. “Is Marriage Good for Your Health?” NY Times. 2010 Apr 12.

23 Prather AA et al.“Behaviorally Assessed Sleep and Susceptibility to the Common Cold.” Sleep. 2015;38(9):135301359.

24 Libzon S et al. “Medical Cannabis for Pediatric Moderate to Severe Complex Motor Disorders.” J Child Neurol. 2018;33(9):565-571.

25 Crippa JA et al. “Translational Investigation of the Therapeutic Potential of Cannabidiol (CBD): Toward a New Age.” Front Immunol. 2018;9:2009.

About the Author(s)

Todd Runestad

Content Director,, Natural Products Insider

Todd Runestad has been writing on nutrition science news since 1997. He is content director for and Natural Products Insider digital magazines. Other incarnations: supplements editor for, Delicious Living!, and Natural Foods Merchandiser. Former editor-in-chief of Functional Ingredients magazine and still covers raw material innovations and ingredient science.

Connect with me here on LinkedIn.


Todd writes about nutrition science news such as this story on mitochondrial nutrients, innovative ingredients such as this story about 12 trendy new ingredient launches from SupplySide West 2023, and is a judge for the NEXTY awards honoring innovation, integrity and inspiration in natural products including his specialty — dietary supplements. He extensively covered the rise and rise and rise and fall of cannabis hemp CBD. He helps produce in-person events at SupplySide West and SupplySide East trade shows and conferences, including the wildly popular Ingredient Idol game show, as well as Natural Products Expo West and Natural Products Expo East and the NBJ Summit. He was a board member for the Hemp Industries Association.

Education / Past Lives

In previous lives Todd was on the other side of nature from natural products — natural history — as managing editor at the Denver Museum of Nature & Science. He's sojourned to Burning Man and Mount Everest. He graduated many moons ago from the State University of New York College at Oneonta.


"There is not a colds-and-flu season. There is a vitamin D-deficiency season."

"There is no such thing as inclement weather. Only improper attire."

Link answers question, "When taking magnesium, should you also take vitamin D3 2,000 IU?"

"Cannabis is nature's most nearly perfect plant."

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