1. Elderberry

Available as a supplement, elderberry is antioxidant-rich and contains vitamin C, a known immune booster. Research shows its potential to accelerate cytokine production to help regulate immune system response. Elderberries are also being studied for their potential to precent flu viruses from taking hold. 

2. Garlic

Enhances immune function to protect against infection and contains other substances (vitamin C, zinc) that support immune response. 

3. Green tea

This superfood offers impressive health benefits including immune support, according to several studies. Sipping tea is a good way to lower stress and relax, but you can also take this as a supplement. 

4. Maitake mushroom

Researchers studying stress's potential to reduce the immune system's ability to fight infection found that an extract of maitake mushroom stimulated phagocytes, white blood cells that target bacteria. A combination of extracts of maitake and the Ayurvedic herb ashwagandha proceed even more effective at reducing stress and boosting immunity. 

5. Olive leaf

Fights bacteria and viruses, and helps defend against colds and flu. Research suggests that its compounds can modulate the body's inflammatory response and promote peak immune system performance. 

6. Probiotics

Gut-friendly bacteria are needed not only for a healthy digestive system but also for a robust immune system Probiotics can be taken supplementally, or eat unsweetened yogurt with live cultures or drink kefir several times a week. Other cultured or fermented foods offer beneficial bacteria too. 

7. Vitamins C, D, E

The immune system requires C to function, and D and E support immunity. Vitamin C aids the production of anti-stress hormones and interferon, an immune system protein, and stimulates production of infection-fighting white blood cells. 

8. Zinc

An essential mineral that promotes healthy immunity, zinc is found in every cell. Following zinc depletion, all kinds of immune cells show decreased function.