Vitamin D has been shown to be crucial in immune function. A 2017 review of 25 studies, published in the British Medical Journal, found that a moderate daily dose of vitamin D may offer protection 

• Get your Vitamin D level checked if you have not yet and supplement as per your doctor’s recommendations
• Healthy adults should receive 2,000 IU of vitamin D 3 daily (as part of a healthy balanced meal or supplement) — you may need more if you get little or no sun exposure. 

Astragalus is a mushroom that is often used in soups or teas. It can be used, alone or in combination with other herbs. Scientific studies have shown its benefit to the immune system. Further studies sponsored by the National Center for Complementary and Alternative Medicine (NCCAM) are ongoing.

The Natural Medicine Comprehensive Database (NMCD) showed that consuming astragalus long-term (at least 6 weeks) might help prevent colds 

• 1 capsules twice a day
• Or get astragalus root to cook in soups and teas

• Species such as shitake, mitake, reishi, oyster have also been shown to be efficacious in improving the immune system
• This one is just an example.
• The best is to eat a variety of steamed fresh mushrooms. Variety is key for your microbiome!

• No evidence on this that I could find; however, the father of Integrative Medicine Dr. Andrew Weil recommends this as it may help reduce risk of contracting viruses in the nasal cavities (cinnamon flavor)

• The evidence on echinacea is mixed.
• Nearly all prevention trials pointed in the direction of small preventative benefits. A 2010 study published in the Annals of Internal Medicine showed that echinacea outperformed both placebo and no treatment at all— but these benefits were too small to be considered statistically significant.  A 2006 review found no evidence that echinacea could prevent colds. But it did turn up findings (albeit inconsistent ones) that products containing the species Echinacea purpurea could lessen a cold’s length and symptoms.

Vitamin C is one of the biggest immune system boosters of all. A lack of vitamin C can even make you more prone to getting sick.

Remember though, Vitamin C has no effect on the RISK of catching a cold. However, it CAN reduce the severity and duration of a cold. 

• It is best to eat foods rich in vitamin C (oranges, grapefruits, tangerines, strawberries, bell peppers, spinach, kale and broccoli. 
• Vitamin C supplements should only be taken with a doctor’s recommendations and best taken only when you’re sick
  • One study showed that 6-8 grams per day may be effective

Elderberry may shorten the duration of flu. Studies are small and more is needed as a method of prevention or treatment for colds and flus.

• One randomized study showed that elderberry may help clear up cold/flu symptoms 4 days earlier than those who took placebo syrup. Another study showed benefits for travelers.

Garlic is a great immune booster. Eating garlic daily is a great way to boost your health and make your food taste great!

• The best way to maintain the effectiveness of garlic is to crush the garlic and let is sit for 10 minutes. This allows for allicin (a phytonutrient responsible for garlic’s health benefits) to be released.
• Here’s a hack on how to always have fresh garlic.