Potatoes and immune function

As winter fades and spring blooms, so do seasonal allergies. With lingering challenges of COVID-19 and flu season, supporting a resilient immune system is more crucial than ever. While the peak of respiratory virus season varies, maintaining a strong immune system is crucial year-round. Despite fluctuations in COVID-19, flu, and RSV hospitalizations, the importance of immune health remains constant.
Registered dietitians understand that the interest in immune health has been significantly heightened since the COVID-19 pandemic, with many people turning to supplementation for enhanced immune function. While it is well documented that malnutrition and certain nutrient deficiencies impair immune function, whether immunity can be enhanced by consuming high levels of these nutrients via supplementation still lacks scientific consensus. Though nutrient supplementation might be necessary in some cases to ensure adequate intake, all of these immune-supporting nutrients can be found in common foods. No single whole food provides all, but some – like potatoes – can deliver a surprising dose in just one serving.
Nutrients that support immunity
Several nutrients including zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C, D, and E, are required to support an immune system capable of mounting a healthy response to invading pathogens. Potatoes and potato dishes can help boost consumption of several of these immune-critical nutrients, along with others, essential for general health and wellness.
In addition to providing 620 mg of potassium (more than a banana), 2 grams of dietary fiber, and 3 grams of high-quality protein, one medium 5.3-ounce potato delivers:

● Vitamin C: 20 mg, 30% DV
While evidence supporting vitamin C as an immunity booster is inconsistent, this antioxidant certainly merits its fame as an immunity superhero. Vitamin C protects immune cells from the very reactive oxygen species they must release to kill pathogens and is used rapidly during active immune responses.
While likely best known for its critical role in immune function, vitamin C is also essential for the synthesis of collagen, which provides structure and elasticity to connective tissues throughout the body, including the skin, which is a primary barrier that acts to keep foreign pathogens out of the body. Another important benefit of vitamin C is that it improves the bioavailability of iron found in plant foods. About 4.5 mg of vitamin C is lost when potato skin is removed.

● Vitamin B6: 0.2 mg, 10% DV
This B vitamin plays an important role in immune function, making it possible for immune cells to proliferate enough to effectively defend against foreign pathogens. While necessary for proper immune function, research indicates that consuming more than is recommended does not further enhance immunity.

● Iron: 1.1 mg, 6% DV
Iron is necessary for both the structure and function of several enzymes that must be present for the immune system to function. The immune system also relies on iron in the production of T lymphocytes. Too little iron certainly impairs immune function, however getting too much can have the same negative impact.

Though not a significant source of iron, potatoes’ impressive vitamin C content, and very low (to nonexistent) antinutrient levels make the bioavailability shine compared to that of many other plant foods rich in iron.

● Polyphenols: Beyond vitamin C, potatoes provide antioxidant polyphenols in varying amounts depending on the variety. Potatoes with colored flesh are rich in polyphenols, purple potatoes in particular. Research suggests that polyphenols may also improve immune function. Many potato types are grown locally in Wisconsin, including different varieties of red, blue and purple, white, yellow-gold, Russet and Fingerling.

● High-quality protein: 3 g
The biological value (BV) of potato protein might surprise you. Depending on the variety, the BV comes in anywhere between 90 and 100 – approaching that of an egg – and is higher in biological value than protein from both soybeans and legumes. While not high in protein, potatoes offer more per serving than most other foods commonly consumed from the vegetables and legumes category.

● Dietary fiber: 2 g, 7% DV
The fiber in potatoes, composed mostly of cellulose, enhances satiety and may contribute to a healthier gut microbiome and help reduce inflammation. In addition, fiber promotes bowel regularity. Fiber is the only nutrient significantly reduced when a potato is peeled. A little less than 50% is found in the skin, so leave the peel on to optimize fiber.

● Potassium: 620 mg, 15% DV
Potassium is necessary for healthy heart and kidney function, muscle contraction, and nerve transmission. Inadequate intake can increase blood pressure and deplete the calcium in bones. Potassium is found primarily in the flesh of the potato. Removing the skin reduces potassium by ~150 mg.