Cold, COVID and Flu Season: Supplements That Promote Your Health

With so many tablets, capsules, gummies, and powders to choose from, which supplements could promote health during cold and flu season? What about probiotic drinks and energy bars? Are they regulated? Are there any studies that can support claims of benefit? Are all of them medically approved?

Key takeaways:
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    The gummy vitamin and supplement industry is growing with most products marketed to children.
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    These chewable vitamins make it easier to maintain healthy levels of important vitamins.
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    Most people can get enough vitamins from their diet by eating raw fruits and vegetables.
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    Adding vitamin C and D during cold and flu season may help boost immunity.
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    Medication interactions can be harmful — check with your doctor before starting a new vitamin or supplement.
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    Keep gummies out of reach of children.

With cold, Covid, and flu season around the corner, it is natural to be thinking about how to stay healthy. A proliferation of gummy vitamins and supplements line grocery store and pharmacy shelves, but convenience should be coupled with caution. These supplements are regulated by the FDA, but as food, not as a drug, so they do not undergo testing for safety, quality, or labeling. The FDA’s oversight role starts after the product enters the market, not before. Given how expensive some of these products are, it is important for the consumer to be educated before making a purchase.

There are two major groups of vitamins: water-soluble and fat-soluble. The water-soluble group includes the B complex and C vitamins while the fat-soluble group includes A, D, E and K. Remembering this dichotomy is important: excess fat-soluble vitamins are stored while unused water-soluble vitamins are excreted. Is there enough evidence to warrant supplementing your daily diet this winter? A balanced view would suggest there probably is, with a few precautions in place.

Vitamin C

This powerful vitamin is an important antioxidant that contributes to tissue repair after exposure to free radicals which are released during metabolism, exposure to the sun, and chemicals. Most people get enough vitamin C through good nutrition, and the effects of high-dose vitamin C have not been proven for preventing or treating disease. However, there is some evidence that routine, daily supplementation may be helpful.

While there may not be sufficient evidence that vitamin C cuts the risk of contracting a cold in the first place, there may be some benefit in reducing the duration of symptoms, with little downside. There is also some evidence to suggest that the risk of a cold could be reduced by half among people undergoing extreme exercise-induced stress, such as marathoners or skiers. Thus, if you are an athlete or have a big event planned and want to optimize your health, this water-soluble vitamin is probably a good bet.

New liposomal vitamin C delivery molecules encapsulated vitamin C to allow better absorption. When you take vitamin C as a tablet or gummy, it must first be digested and then processed by the liver. The advantage of liposomal delivery is better bioavailability. This newer technology may improve infant formula as well, but for the time being, it probably deserves more study and may be more expensive.

Where to find Vit C: Fresh fruits and vegetables (eat them raw), such as tomatoes, broccoli, Brussels sprouts, cabbage.

Vitamin D

Exposure to the sun synthesizes vitamin D in the skin, and when activated as a steroid hormone, this vitamin exerts important effects on the immune system. In the lining of the airways, activated vitamin D promotes the expression of peptides, which are short chains of amino acids. These peptides are found in white blood cells (monocytes and neutrophils) as well as T cells in the membranes lining your airways. Part of your innate immune system, these defenders are constantly looking for invading microorganisms.

The natural killer (NK) T cells are particularly interesting because they also destroy pre-cancerous tumor cells. While on patrol, the NK cells look for markers that communicate that a cell is “self.” A tumor cell often loses this marker, at which point the NK cell may “switch on” and destroy the abnormal cell. Because of this unique signaling capability, the NK cells are an attractive target for cancer therapy.

Where to find Vit D: Fish, eggs and milk. However, most of us do not get enough vitamin D, so a daily supplement of 1000-2000IU may be helpful.


Another fascinating weapon against viral or bacterial invaders is zinc, which can be used to fight infection. Zinc lozenges are advertised to reduce the severity and duration of illness, and zinc supplementation has been studied as part of a strategy to boost immunity among the elderly, and combat diarrhea in children, but what is the mechanism underlying this defense? Zinc may bind in places where other metals normally would, increase susceptibility to oxidative stress, and disrupt pathogen growth pathways. Zinc may also work cooperatively with copper in what von Pein and coauthors describe as a “brass dagger” defense.

To leverage this advantage, innate immune cells can mobilize zinc along inflammatory pathways to aid in cell signaling. The precise mechanisms involved are a fascinating and emerging field of interest in immunology. One tactic that innate immune cells can deploy is mobilizing zinc from storage to kill invading pathogens. Naturally, the pathogens have evolved their own defense mechanisms and can export zinc when levels get too high. Thus, zinc homeostasis is important for living things, and too much of a good thing is not necessarily good. Plus, taking zinc on an empty stomach can make you feel a bit nauseous.

Where to find zinc: the maximum recommended amount according to the Mayo Clinic is 8 mg for women and 11 mg for men (FDA says 11mg); find zinc in chicken, red meat, and fortified breakfast cereals.

Interactions with other medications

People who are taking a daily prescribed medication need to be cautious when adding a dietary supplement or herbal tea to their daily routine. At your next routine visit, bring a bag or list of your supplements and allow your doctor a chance to review any interactions which may be harmful. In some cases, supplements have been found to contain drugs that were not identified on the label or make false claims. This puts the consumer in a difficult position, but using common sense — such as purchasing reputable brands and minimizing the number of supplements you take — can help your doctor troubleshoot health concerns.

Precautions include potential overdose

Consumers also need to be aware of the possibility of overdose among children. Most gummy supplements are marketed to children, and a study of calls to a poison control center found that the median age of children visiting an emergency department was 3 years, mostly for vitamin-related overdose concerns. However, the authors expressed caution about the safe storage of melatonin, which prompted nearly a quarter of all calls to the center. Children who ingested melatonin were 8 times more likely to experience symptoms following the overdose.

The immune system involves many complex interactions between generalist defenders (innate immunity) and trained specialists (antibodies and T cells). Eating a healthy diet and taking daily vitamin supplements such as C and D may promote immune health. Zinc may also be helpful if taken within 24 hours of getting a cold, but do not take intranasal (spray) zinc because this can cause you to lose your sense of smell. Finally, staying hydrated allows these cells to move around freely and complete their patrols, processing pathogens out of your system.

Everyday choices add up to better health

Probiotics do contribute to overall gut health and immunity and are an area of increasingly encouraging research regarding how diversity in the microbiota promotes overall health and may even help address certain chronic conditions. If you are in line at the grocery store and have the option to choose a probiotic drink or a diet soda, the former likely confers more health advantages. Similarly, energy bars would serve as a good alternative to a high-sugar candy bar. Health literacy begins with these everyday decisions. Allow your child the chance to compare the packaging and pick the one with the lowest sugar and highest vitamin content then do further research at home to decide if you made the best choice. You probably did!

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