Get full access to Outside Learn, our online education hub featuring in-depth nutrition, fitness and adventure courses, and more than 2,000 instructional videos when you sign up for Outside+..
As winter approaches, we’re all thinking about bolstering our defenses against colds and flu. But a robust, well-balanced immune system does more than fight off bacteria and viruses; it’s key in preventing more serious diseases, like hepatitis, leukemia, and other cancers.
This year, as cold and flu season enters its wintry worst, fight back: keep your system rock-solid, with these 10 super-immune supplements to maximize your pathogen-fighting potential—and set you up for long-term health.
10 Immune Boosting Supplements:
1. Vitamin C
This powerful antioxidant has antimicrobial activities, improves components of the immune system, and reduces the risk, severity, and duration of infectious disease. Some studies show that large doses taken at the onset of colds can lessen symptoms. More importantly, vitamin C may also protect against some forms of cancer, including pancreatic, breast, colon, and cervical cancer.
Reishi, maitake, cordyceps, and other medicinal mushrooms contain immune-enhancing lentinan and other compounds that ward off viral infections, lower inflammation, and help prevent bronchitis and flu. Studies have also shown their effectiveness in treating HIV-infected patients, reducing cancer risk, and inhibiting the growth and spread of tumors.
This trace element is crucial for the development of white blood cells that destroy bacteria and viruses, and even mild deficiencies can increase the risk of infection. Studies show zinc may reduce the length and severity of the common cold, especially when taken as lozenges the first 24 hours of onset of symptoms. Other studies show zinc supplementation inhibits the growth of cancer cells and induces apoptosis (cancer cell death) and can help protect against prostate, lung, bladder, and other cancers.
Used for hundreds of years in herbal medicine, echinacea (purple coneflower) petals, leaves, and roots have anti-inflammatory and immune-boosting properties, and can shorten the duration and severity of colds and upper respiratory infections when taken as soon as symptoms appear. Some studies suggest echinacea may also reduce cancer risk.
This berry is a powerful antiviral and antimicrobial, and can ward off colds and flu. In one study, people who took elderberry had a shorter duration of colds, with fewer symptoms. In another study, a standardized black elderberry extract protected against 10 strains of influenza virus, and shortened the duration of flu symptoms.
These beneficial bugs have potent antiviral effects, and can fight stomach bugs and other infections. Studies show probiotics shorten the duration of the common cold and respiratory viruses. In one trial, people who took probiotics regularly had fewer illnesses and shorter episodes of illness. Other studies suggest probiotics protect against cancer, reducing invasion and spread of cancer cells.
7. Oregano oil
Extracted from the oregano plant, oregano oil is rich in carvacrol, a phytochemical with antiviral, antibacterial, and anti-inflammatory properties. Oregano oil extracts have been shown to inhibit the activity of the influenza virus and help dilate the bronchi, increasing airflow to the lungs and making it easier to breathe during respiratory tract infections. Other studies suggest carvacrol induces apoptosis, or cancer cell death.
This bitter herb works by reducing inflammation, fighting viruses, and enhancing immune function. Andrographis extract wards off flu and reduces the intensity of common cold symptoms; in one study, it was 53 percent more effective than a placebo in reducing respiratory tract infection. Other studies show it inhibits the proliferation of tumor cells and can protect against colon, esophageal, prostate, gastric and other forms of cancer.
9. Olive leaf extract
Olive leaf extract is rich in a variety of antioxidant polyphenols that have antiviral, antibacterial, and anti-inflammatory actions, and can ward off colds and flu. Other studies show olive leaf extract can prevent DNA damage and reduce cancer risk.
A trace mineral found in seafood, nuts, and seeds, selenium helps enhance immune response, improve resistance to viral infections and fight infection. Many studies also show selenium protects against cancer and prevents the spread of cancer cells.
Tips for Boosting Immunity
Diet, weight, sleep, and stress all affect immune response. Give your system the upper hand, with these strategies for disease-free living.
- Minimize meat. Instead, focus on fruits, vegetables, nuts, seeds and legumes; they’re rich in antioxidants, healthy fats, and fiber to support immune health.
- Slim down. Some studies suggest excess body fat triggers inflammation and upsets the immune system. Additionally, obesity increases the risk of complications and death from influenza infection.
- Sober up. Alcohol disrupts the immune system and impairs the body’s ability to prevent infection. Drink in moderation, and stick to red wine; it’s high in resveratrol, which supports immunity.
- Swap coffee for tea. Tea is rich in L-theanine, which increases the body’s levels of virus-fighting compounds, and green tea also contains epigallocatechin (EGCG), a powerful immune booster.
- Grab your mat. Yoga enhances immunity by lowering stress, reducing inflammation, and upping the body’s levels of cytokines, chemicals that regulate immune response.
- Spice up your meals. Garlic is rich in compounds that increase immune-system activity, ginger is a potent antimicrobial, and capsaicin, the spicy component in cayenne pepper, protects against viruses.
- Kick sugar. It decreases the ability of white blood cells to engulf bacteria, and hampers immune response. If you crave sweets, stick to raw, unfiltered honey or Manuka honey—both inhibit the flu virus.
- Sleep better. Peaceful slumber is critical for a strong immune system, and chronic sleep deprivation can increase your susceptibility to pathogens.
- Chill out. Chronic stress dysregulates immune responses by altering cytokines, increasing inflammation, and suppressing immunoprotective cells. Over time, ongoing stress can contribute to cancer and other diseases.