The immune system is a complex collection of cells and tissues that act as the body's defense against harmful microbes. Many factors can negatively impact immune health, including stress, nutritional deficiencies and genetic factors. In some instances, herbs and vitamins may help improve immune function by correcting deficiencies, fighting pathogens or directly strengthening the immune system itself.
Garlic
Garlic is an herb with powerful immune-boosting properties. It is rich in sulfurous compounds like allicin that have antibacterial, antiviral and antifungal effects. According to the "American Journal of Clinical Nutrition," garlic may reduce the risk of several types of cancer, including oral, esophageal, colorectal and breast cancers. In addition, it is a good source of important vitamins and minerals like selenium, manganese and vitamin C, all of which are required for healthy immune function.
Side effects of garlic include nausea, indigestion and an increase in body odor. Because it can thin the blood, garlic should not be taken with blood thinners like aspirin or warfarin.
Astragalus
Used for millennia in traditional Chinese medicine, astragalus is an herb with unique immune-enhancing effects. As an adaptogen, astragalus protects against the negative effects of stress, such as adrenal fatigue and physical exhaustion. It has antioxidant and antimicrobial properties and has been used traditionally to treat and prevent cold and flu, fatigue, and allergies. According to the University of Maryland Medical Center, astragalus effectively stimulates the immune system, fights inflammation and kills harmful germs like viruses and bacteria.
Astragalus is generally well-tolerated, though it can cause interactions with immune-suppressing drugs. The average dose is 500 to 1,000 mg up to four times daily.
Vitamin C
Ascorbic acid, better known as vitamin C, is a vital component in immune health. It has antioxidant properties that help protect against free radical damage, which plays a role in harmful processes like aging and cancer. When taken in conjunction with zinc, vitamin C shortens the recovery period of respiratory infections like the cold and flu, according to an abstract on PubMed.gov.
Guavas, tomatoes and citrus fruits like oranges and lemons are excellent sources of vitamin C. Taking vitamin C in supplement form may help you meet your daily needs. The recommended daily intake of vitamin C is 500 to 1,000 mg.
Selenium
Selenium is a mineral required for optimal immune function. It is needed to balance with zinc and for the activation of immune components like interferon and T-cells. According to the "American Journal of Clinical Nutrition," supplemental selenium stimulates the activity of helper cells, boosts production of cytokines and speeds the removal of the polio virus from the body.
Due to poor soil conditions used to grow many modern food crops, selenium deficiency is very common today. Taking a multivitamin that contains 45 to 60 mcg selenium can help you to reach your optimal daily allowance of the mineral.
References
- "American Journal of Clinical Nutrition": Onion and Garlic Use and Human Cancer
- University of Maryland Medical Center: Astragalus
- PubMed.gov: Immune-Enhancing Role of Vitamin C and Zinc and Effect on Clinical Conditions
- "American Journal of Clinical Nutrition": An Increase in Selenium Intake Improves Immune Function and Poliovirus Handling in Adults With Marginal Selenium Status
