Fermented foods and probiotic supplements can help reduce the risk of infection by supporting a healthy gut microbiome and anti-inflammatory pathways. Research shows that maintaining a diverse and balanced microbiome is key to a strong immune system and ability to fight viruses and bacteria. Both probiotics and fermented foods provide live microbes that compete against pathogens. Zinc plays an important role in immunity by supporting immune cell function and responses to infection. Studies found that zinc supplements taken within 24 hours of cold symptoms can shorten the duration and severity of colds. However, most zinc supplements contain levels above the tolerable upper intake limit of 40mg per day, which can cause side effects. Vitamin C is essential for immune

2. Fermented foods and probiotics can have anti-inflammatory and anti
pathogenic effects
Your gut contains a rich community of healthy microbes that compete against
invading pathogens, acting as your body’s first defense against infection. They
also digest nutrients that you otherwise couldn’t (like fiber and other
carbohydrates) in a process called fermentation, which results in byproducts that
play many important roles in the body from protecting the colon to improving
insulin sensitivity.
Research, especially of late, has found that your microbiome is a key
component of a healthy immune system and your body’s ability to fight off viral
and bacterial infections.
Both probiotic supplements and fermented foods—which are sources of live
microbes—can significantly reduce your risk of infection by fighting pathogens in
the gut and contributing to anti-inflammatory pathways around the body.

3. Zinc makes an infection less severe—but common supplements exceed a
safe limit of intake
Zinc plays an important role in immunity, as it's involved in your body's cell-
mediated and humoral immune responses (two types of immunity where a
specific immune response is generated for a particular pathogen). Low or
deficient levels of zinc, therefore, profoundly affect the number of your immune
cells that are available to fight an invader. After examining 13 randomized
placebo-controlled studies between zinc and the common cold, researchers found
that taking zinc within 24 hours of the first signs of cold could shorten its duration
and make the symptoms less severe.
Men and women need 11mg and 8mg of zinc per day, respectively. It's
found primarily in red meats and seafood, especially oysters and mollusks. Zinc is
also found in plant sources like whole grains and legumes, but in much lower
quantities and with lower absorption than that from animal products. Vegetarians
and the elderly, therefore, are at particular risk for insufficient zinc intake from
diet alone.

4. While it is important to meet your zinc needs, it's equally as important to not
go overboard. The maximum amount of zinc you should take in a day is 40mg—
known as the Tolerable Upper Intake Level established by the Food and Nutrition
Board. Intakes above 40mg can cause copper deficiency and neurological
problems. Most supplements and zinc-based cold remedies offer levels above
this upper limit, so be diligent about which bottles you choose from the shelf.
Vitamin C's reputation for immune support is justified - but more is
worse, not better
We can’t talk about immunity without addressing vitamin C. Like zinc,
vitamin C is an essential micronutrient that we must obtain from our diets. It plays
an important role in immunity by acting as an antioxidant, enhancing immune cell
function and supporting anti-inflammatory pathways in the body.
A vitamin C deficiency can therefore lead to impaired immune function and a
higher susceptibility to infections. This review looked at hundreds of studies
examining vitamin C’s role in immunity. The researcher concluded
that supplementing with vitamin C at around 100-200mg per day may prevent
respiratory infections.

5. A typical Airborne packet or supplement has around 1,000mg of vitamin C!
And what’s more, the absorption of vitamin C decreases with increased intake.
For example, only 16% is absorbed at high intakes (~1,200mg) but up to 98% is
absorbed at low intakes (<20mg).
Once you hit 1,000mg, approximately less than 50% of the vitamin C you
consume will be absorbed—and the rest will just be excreted in the urine.
Therefore, vitamin C is best taken in two to three smaller doses with meals.
Toxicity of vitamin C is unusual, but adverse effects may increase if you
supplement above the Tolerable Upper Intake Level (2,000mg per day) in the
long-term.
Vitamin C is most abundant in fresh, whole foods like pineapple, kiwi, and
broccoli. And the lack of fresh produce in the typical U.S. diet (among other
reasons) has caused vitamin C deficiency to be one of the leading nutrient
deficiencies in the country. As a water soluble vitamin, vitamin C is never stored
in the body. We, therefore, must focus on eating vitamin C-rich foods every day to
meet our needs.