With winter on its way, it’s time to bolster our health for flu season. Three superfoods—sweet potatoes, spinach, and garlic—can improve immune function and support our fight against various diseases.

If you’re prone to colds, fatigue, or seasonal allergies, your symptoms might reflect a weakened immune system.

In traditional Chinese medicine, it is said that “food and medicine come from the same source,” meaning food can be used as medicine. It is therefore recommended that you eat foods that boost the immune system.

Sweet Potatoes

Sweet potatoes are rich in vitamin A, primarily because of their beta-carotene. One sweet potato can have up to 156 percent of the recommended daily intake of vitamin A.

Vitamin A is important for the health of the immune system. It protects the skin and serves as the body’s first barrier against infection. The operation of immune cells also depends on vitamin A. Studies have found that a lack of vitamin A can impair the proper function of the immune system and destabilize the intestinal microbiota, as intestinal microorganisms are also critical to immune function.

Sweet potatoes are rich in dietary fiber, which can promote the growth of intestinal probiotics. Through fermentation of probiotics, dietary fiber can produce short-chain fatty acids that are particularly important for health and that help fight inflammation in the brain and the body. Moderate consumption of sweet potatoes can improve immunity, help improve digestive function, and prevent constipation.

Sweet potatoes are nutritionally balanced, with fewer calories than rice. They can be baked, steamed, grilled, eaten as a main or side dish, or cooked, cubed, and added to salads.

Spinach

Spinach contains a variety of antioxidants, such as flavonoids. Research has found that the active ingredients in spinach can:

• Remove reactive oxygen species that could cause cell damage
• Prevent oxidative damage to biological macromolecules such as proteins and ribose
• Regulate the expression of antioxidant and anti-inflammatory genes
• Promote the secretion of hormones related to satiety
• Assist weight loss

It also has anti-cancer, blood lipid-lowering, and blood sugar-lowering functionalities.

Spinach is rich in iron, an important trace element for immune function. Studies have found that iron deficiency can diminish immune response. Activated T lymphocytes require a large amount of iron. Without sufficient iron, the energy produced by the mitochondria in T lymphocytes is reduced, and the T cells can’t play their role in combating infection.

Spinach is easy to incorporate into a diet— it can be stir-fried, added to soups, made into salads, and more.

Garlic

Garlic has been used for centuries as a natural medicine to boost immunity and prevent disease. It contains a compound called allicin, which has powerful antibacterial, antifungal, and antiviral properties.

Garlic is multifunctional; it helps prevent and treat ailments such as tumors, cardiovascular diseases, and Alzheimer’s disease. It can also remove heavy metals from the body.

Tips on Eating Garlic

Garlic is a common spicy condiment in Eastern and Western cuisine. Chopping or mashing garlic and letting it stand for 10 minutes before cooking activates its allicin and maximizes its health benefits. Studies have found that minced garlic retains more of its active ingredients after cooking than whole garlic.

Adding sweet potatoes, spinach, and garlic to your daily diet can provide additional seasonal support to your immune system.