For this month’s conversation with Cynthia Sass (MPH, MA, RD, CSSD), UPGRAID's nutrition consultant and registered dietician weighs in on just how valuable a nutritious diet can benefit your immune system and keep your health in check so that you can give yourself the best chance to fight getting sick.
Upgraid: Can certain foods potentially weaken immunity?
Cynthia: Your overall eating pattern is more impactful than any one food. However, minimizing certain foods can help maintain a stronger immune system. For example, excess alcohol consumption has been linked to a weakened immune response, with effects that may include an increased susceptibility to pneumonia, a greater likelihood of developing acute respiratory distress syndrome (ARDS), and a slower and less complete recovery from infections. Both animal and human studies have shown that excess sugar can interfere with the ability of immune cells to attack bacteria. COVID-19 is viral, but secondary bacterial infections can occur. Animal studies have also linked very high sodium intakes to suppressed immune function. Processed foods are the top source of excess sodium, and also weaken immunity via inflammation. And while coffee and tea are potent health protectors due to their high antioxidant levels, overdoing it on caffeine can interfere with sleep, which can increase inflammation and compromise immune function.
Upgraid: Can certain eating habits weaken immunity?
Cynthia: In addition to consuming too much alcohol, sugar, processed foods, and caffeine, immune function can be compromised by habits that include skipping meals, not properly hydrating, and eating an unbalanced diet. In other words, it’s not just what you do eat, such as sweets or frozen dinners, but also what you don’t eat (like too little water, produce, and protein) that may weaken immunity.
Upgraid: Can certain foods strengthen immunity?
Cynthia: While no food or nutrient can ensure that you won’t ever contract the coronavirus, flu, or any other illness, some foods have been shown to help bolster immunity.
Certain foods support healthy immune function because they are rich in a key nutrient that plays a role in how the immune system works. For example, one medium orange provides about 75% of the daily target for vitamin C, and a medium raw red bell pepper packs 166%. While vitamin C can’t prevent illness, it has been shown to improve outcomes in people with respiratory infections, with benefits primarily seen in those who had suboptimal blood vitamin C levels.
Sunflower seeds and almonds provide vitamin E, which plays a key role in immunity. This fat soluble vitamin boosts the activity of immune cells to support the body’s ability to fend off invading bacteria and viruses.
Sweet potato and carrots are top sources of beta carotene, a precursor to vitamin A. This nutrient aids the immune system by helping to produce white blood cells, which fight bacteria and viruses. It also helps form the mucous membranes that line the respiratory tract, which serve as a protective barrier to keep germs out of the body.
Pumpkin seeds vegetarian baked beans provide zinc. The production of certain immune cells is limited when zinc intake is low, and adequate zinc is crucial for the normal development and function of the immune system.
Green vegetables have been shown to contain bioactive compounds that release a chemical signal that optimizes immunity in the gut, the location of 70-80% of immune cells. Research has specifically zeroed in on cruciferous green veggies, like kale, cabbage, broccoli, and Brussels sprouts.
Other foods have been shown to support immunity via their antimicrobial and anti-inflammatory activity, such as mushrooms, garlic, pomegranate juice, berries, green tea, spices, extra virgin olive oil, and others.
Upgraid: How do overall eating habits impact immune function?
Cynthia: Consistency is key. I recommend striving to eat regularly timed well-balanced meals comprised primarily of whole plant based foods. If your eating is somewhat erratic, try to establish a routine in terms of the timing and composition of meals or snacks. Start with a few healthy and simple go-to options, like a smoothie made with greens, frozen berries and a few dates or banana slices, plant protein powder, nut butter, and fresh ginger, or a bowl made with a generous portion of greens and other veggies topped with lentils, quinoa, and avocado. Staying hydrated is also important. Aim for 64 ounces of water consumed evenly throughout the day.
Upgraid: How is fiber tied to immunity?
Cynthia: In addition to supporting good digestive health, research shows that a higher intake of dietary fiber and prebiotics support healthier immune function, including protection against viruses. Prebiotics, which are found in many plant based foods, essentially feed beneficial microbes in the gut that interact with the immune system. As I previously mentioned, the gut is the location of 70-80% of immune cells.
Upgraid: In addition to being a registered dietitian nutritionist you also have a master’s degree in public health. What are some other health habits that affect immune function?
Cynthia: Apart from healthy eating, the most impactful habits that support immune function are: getting enough sleep; managing stress; being regularly physically active; not smoking; and maintaining good personal hygiene, including proper hand washing. If all of this seems a bit overwhelming, try to focus on one goal at a time. Meditation is a great place to start. Just five minutes a day of guided meditation can help reduce stress, improve mindful eating, and support healthy sleep.