Can food really boost your immune system?

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From “superfoods” to pricey supplements, we’re constantly told there are quick fixes to keep illness at bay. But can you really boost your immune system—or is it more about balance and consistency?

To help clear things up, we asked Dr. Ian Campbell to share his expert take on what actually supports the immune system—and what’s just clever marketing.

Can you really “boost” the immune system?

“The idea of ‘boosting’ immunity is a myth,” says Dr. Campbell. “There’s no evidence that specific foods or supplements can make the immune system work beyond its natural capacity. What we can do is support it—and a balanced diet rich in vitamins, minerals, and phytochemicals plays a key role in that.”

Phytochemicals are naturally occurring compounds found in fruits and vegetables that may help reduce inflammation. “Different colors in fruits and veggies often reflect different phytochemicals, so the more colorful your diet, the wider the variety of beneficial compounds you’re getting,” Dr. Campbell explains. “The evidence isn’t conclusive, but eating at least five servings a day is proven to support overall health—and there’s no downside.”

Which nutrients matter most?

Several vitamins and minerals are essential for a healthy immune response. “Vitamins A, B6, B12, and D are especially important,” says Dr. Campbell. “That’s why vitamin D supplements are recommended for people with little sun exposure in winter. For some, a general multivitamin can also serve as a helpful backup to ensure sufficient intake, though most needs can be met through a healthy, varied diet. Iron, copper, folate, zinc, and selenium also play important roles, and you can get enough of these by eating a wide range of foods.”

The gut is also a key player in immune health. “Prebiotic foods—like vegetables, whole grains, beans, and legumes—feed the good bacteria in your gut. Probiotic foods such as live yogurt and some cheeses can help support healthy microbes too. A diverse microbiome is increasingly recognized as essential to immune function.”

What about lifestyle habits?

Dr. Campbell explains that diet is only part of the equation. “Lifestyle choices make a big difference,” he says. “Chronic stress, lack of sleep, heavy alcohol use, or extreme exercise routines can all weaken immunity. On the other hand, getting enough rest, staying hydrated, exercising regularly, and managing stress can boost both how you feel and how well your immune system performs.”

Our highly processed modern diets may also play a negative role. “Ultra-processed foods, along with those high in sugar and unhealthy fats, can damage the gut microbiome—which is closely linked to immune health.”

Does being in a calorie deficit affect immunity?

It depends on how you approach it. “A modest calorie deficit—like the one most people follow for gradual weight loss—won’t harm the immune response,” says Dr. Campbell. “But very restrictive diets can. Even smaller deficits can become problematic if your diet lacks nutrient-rich foods over time.”

So what’s the solution? “Think long-term,” Dr. Campbell advises. “Keep your calorie deficit moderate, stay active, and most importantly, make sure your diet is balanced, colorful, and full of nutrients. That way, you can lose weight while still supporting your immune health.”

Final thoughts

“A strong immune system is essential for a healthy life,” says Dr. Campbell. “There’s no quick fix and no real ‘immune system booster.’ But by eating a varied, nutrient-dense diet, maintaining a healthy weight, staying active, and taking care of your sleep and stress levels, you’re giving your body the best shot at staying well.”

Expert opinion

“There aren’t any foods or supplements that truly ‘boost’ immunity—but there’s plenty we can do to support it. Focus on a varied, colorful diet, prioritize sleep, manage stress, limit alcohol, and avoid ultra-processed foods. The basics really do work.”

Dr. Campbell’s 5 tips for supporting immune health

1. Eat a colorful, varied diet with plenty of fruits, vegetables, and whole grains.
2. Take a vitamin D supplement during winter if you get little sun exposure.
3. Prioritize sleep and manage stress whenever possible.
4. Stay active with regular, moderate exercise.
5. Limit alcohol and ultra-processed foods.