If you want to support your immune system, there's one breakfast immunology experts recommend having more often: a produce-packed smoothie. In particular, they urge including dark leafy greens like spinach or kale as well as lemon juice, pineapple or mango, strawberries and flax seeds.
Your diet plays a role in keeping your immune system in tip-top shape, helping to protect you from toxins and infections, according to the Cleveland Clinic. However, popping a supplement or just eating an orange won't help — your immune system needs a balanced diet filled with healthy foods over time.
That's where regularly incorporating a healthy smoothie into your breakfast routine can help.
"Colorful plant-based foods, specifically fruits and vegetables, are the cornerstone to an anti-inflammatory, antioxidant-rich diet that powers your immune system," says Casey Kelley, MD, an immunology expert, founder and medical director of Case Integrative Health.
"Foods high in these nutrients are easy to work into a delicious breakfast to make sure you start every day off right. Typically, I have a smoothie every morning."
Of course, no single food or supplement can prevent you from getting sick with, say, COVID-19 or other illnesses, but eating healthy does help you fight all diseases more effectively, per Nebraska Medicine. While it doesn't replace standard mitigation efforts like wearing a mask or social distancing, a healthy diet can help reduce inflammation, too much of which can hamper your ability to fight off invaders like the coronavirus.
Specifically, a proper diet can affect your immune system through gene expression and cell activation — putting your body in the strongest possible state to battle viruses and other invaders, per a May 2020 article in the Pakistan Journal of Medical Sciences.
Here's why blending up a smoothie, in particular, can help bolster your immune system and keep you healthy.
Why You Should Wake Up to an Immune-Supporting Smoothie
1. You’ll Get a Burst of Vitamin C
It's easy to fit vitamin C into a smoothie through fruits and vegetables. "Research has shown that vitamins C, D and E can help to stimulate the immune system," says Sanjeev Jain, MD, a board-certified immunologist at the Columbia Asthma & Allergy Clinic.
The juice of just one lemon contains 21 percent of your Daily Value (DV) of vitamin C while one cup of pineapple chunks contains 88 percent of your DV. To top it off, one cup of sliced strawberries contains 108 percent of your DV of vitamin C.
Vitamin C is essential for your body's healing processes — and as an antioxidant, it helps protect your cells against the effects of harmful free radicals (molecules produced when your body digests food or is exposed to tobacco, sunlight and other sources), per the Mayo Clinic.
Extremely active people (think marathon runners and skiers) who took at least 200 milligrams of vitamin C daily (about the amount in two oranges) were observed to cut their chances of getting a common cold in half, per a January 2013 review of 29 randomized trials in the Cochrane Database of Systematic Reviews.
While the same effect wasn't seen for the general population, taking in 200 milligrams of vitamin C daily is tied to reducing the duration of cold symptoms by 8 percent in adults and 14 percent in children. That equates to about one day less of sickness.
You may be tempted to pop a vitamin C supplement and call it a day, but fitting this micronutrient into your morning smoothie is far more delicious — and effective for your overall health.
For example, people with high intakes of vitamin C from fruits and veggies were observed to have a reduced risk of colon, lung and breast cancers, but vitamin C supplements don't appear to have the same protective effect, per the National Institutes of Health.
2. You’ll Slurp Up Vitamins A and B
Both of these micronutrients are important for your immune system. "Personally, I try to eat something containing vitamins A and B every morning," Dr. Kelley says. "Smoothies can be an easy, quick way to get all of your critical nutrients together each morning."
One cup of pineapple chunks contains vitamins B1, B2, B3, B5, B6 and B9. A tablespoon of flax seeds also includes 14 percent of your DV of vitamin B1.
Meanwhile, mangos are a source of vitamin A, with 10 percent of your DV in one cup. They also contain many B vitamins, including 18 percent of your DV of vitamin B9.
Vitamin A is known as the "anti-infective vitamin" and is tied to preventing the development of autoimmunity, per Oregon State University.
Meanwhile, B-complex vitamins are sometimes called "anti-stress vitamins" because they're linked to strengthening the immune system and improving the body's resilience to stressful conditions, per Mount Sinai.
3. It’s One Way to Fit in More Fiber
Move over, fruit juices: While you may see "cold-fighting" or "immunity-boosting" drinks at your local juice shop, smoothies provide the fiber that supports the immune system.
The fiber in fruits, vegetables and seeds in your smoothie will benefit your immune system by fortifying your gut health. A high-fiber, plant-rich diet supports the growth and maintenance of healthy microbes, per the Harvard T.H. Chan School of Public Health.
Those microbes break down fibers (sometimes called prebiotics, because they feed microbes) into short-chain fatty acids that stimulate immune cell activity.
Tips for Making an Immune-Supporting Smoothie
Immune experts love smoothies because they're an easy way to fit in a variety of immune-supportive foods into one meal.
"A varied diet that includes adequate macronutrients (carbs, fat and protein) and micronutrients (vitamins and minerals) can help you to achieve optimal immune function," Dr. Jain says. Plus, it's a great replacement for less healthy breakfast foods, which can hamper your immune function.
"Diets high in calories and low in basic nutrients, often seen in fast food or processed foods, can contribute to poor immune function," Dr. Jain adds. "We recommend avoiding breakfast foods that contain empty calories, such as sugar-sweetened cereals, pastries, sweetened applesauce and sugary juices."
- Try to fit a variety of fruits and vegetables into your smoothie, and blend it all together in two separate steps. "I try to include a handful of the dark leafy greens and blend that with liquid first, like water or coconut milk," Dr. Kelley says. "Then, I add fresh or frozen fruits and the seeds and blend everything together. This is how you attain the best consistency."
- You can also add a booster to your smoothie: "If you're really wanting to utilize breakfast as a way to boost your immune function, consider adding a high-quality liquid K2 + D3 vitamin combo at the end of your smoothie blend to take your vitamin boost over the top," Dr. Kelley says.
Vitamin D is essential for immune system support (but can sometimes be difficult to find in breakfast foods — you can find it in mackerel and tuna), per the Cleveland Clinic. Meanwhile, evidence suggests that vitamin K has anti-inflammatory effects, per a June 2016 study in Current Nutrition Reports.
- Cleveland Clinic: "8 Vitamins & Minerals You Need for a Healthy Immune System"
- Nebraska Medicine: "Fight coronavirus with food"
- Pakistan Journal of Medical Sciences: "How Nutrition can help to fight against COVID-19 Pandemic"
- MyFoodData: "Lemon Juice Raw"
- MyFoodData: "Pineapple"
- MyFoodData: "Strawberries"
- Mayo Clinic: "Vitamin C"
- Cochrane Database of Systematic Reviews: "Vitamin C for preventing and treating the common cold"
- National Institutes of Health: "Vitamin C"
- MyFoodData: "Flax Seeds"
- MyFoodData: "Mangos"
- Oregon State University Linus Pauling Institute Micronutrient Information Center: "Overview of the Immune System"
- Mount Sinai: "Vitamin B1 (Thiamine)"
- Harvard T.H. Chan School of Public Health: "Nutrition and Immunity"
- Current Nutrition Reports: "The Role of Vitamin K in Chronic Aging Diseases: Inflammation, Cardiovascular Disease, and Osteoarthritis"