Immune-Boosting Nutrition for Athletes: How to Stay Healthy, Prevent Illness, and Recover Faster

Prefer to watch and listen? This blog post was inspired after creating Episode #245: Immune Boosting Nutrition for Cold and Flu Season.

How Nutrition Can Boost Your Immune System: What Every Athlete Needs to Know

For athletes, staying healthy isn’t just about performance — it’s about consistency. Training breaks down the body to build it back stronger, but when the immune system struggles, recovery plummets, fatigue increases, and performance inevitably suffers. As cold and flu season approaches, immune-boosting nutrition for athletes becomes a critical part of their toolkit.

What many athletes don’t realize is that immune resilience isn’t solely determined by genetics or luck. It is profoundly shaped by nutritional intake, recovery habits, and energy availability.

The Research: Why Athletes Are at Higher Risk for Illness

Sports science has long recognized that athletes experience higher rates of upper respiratory illness (URI) compared to the general population. In fact, 35–65% of athlete illnesses in sports medicine clinics are attributed to upper respiratory illness. Research also shows that athletes face an even higher risk during periods of intense training or heavy competition loads (1).

But the greatest risk factor of getting sick? Underfueling.

Both the IOC Consensus Statement (2014) and the 2023 IOC Consensus Statement on REDS highlight that athletes experiencing REDS — Relative Energy Deficiency in Sport — have reduced immunity, increased susceptibility to illness, and measurable worsening of immune biomarkers (2,3).

This means that when athletes fail to meet their energy needs, their immune system becomes compromised. Training stress rises, recovery declines, and the risk of catching the common cold, flu, or other infections increases dramatically.

In short: Low energy = low immunity. Consistent fueling = protection + performance.

So how can athletes strengthen their immune system through smart nutrition? Read on to find out.

Tips for athletes to prevent sickness with Immune-Boosting Nutrition

1. Stay Adequately Fueled: The MOST Important Immune Strategy

Before supplements, before superfoods, and before herbal remedies, enough calories is the #1 factor in immune resilience. Underfueling — even unintentionally — weakens immune function. When calorie intake is too low:

• white blood cell activity decreases

• inflammation increases

• stress hormones rise

• recovery slows

• illness risk spikes

If you're training hard, you need to be eating enough to support both physical output and immune defense. Adequate fueling is the foundation of nutrition for immune health.

2. Prioritize Vitamin C, Vitamin D, and Zinc

These immune-boosting nutrients are vital for athletes who want to recover faster and avoid seasonal illness.

Vitamin C

Supports white blood cell activity and may shorten the duration of illness. Food sources: citrus fruits, strawberries, peppers, leafy greens. Throughout cold and flu season, I often recommend that athletes build a daily habit of consuming 8oz of 100% orange or grape juice to ensure adequate vitamin C intake.

Vitamin D

Essential for immune regulation — especially in winter months or for indoor athletes. Food sources: fortified foods such as cow's milk, fatty fish including salmon, egg yolks, and sunlight. Throughout cold and flu season, I often recommend that athletes build a weekly habit of consuming fatty fish for dinner at least once a week, such as salmon, mackerel, herring, trout, or sardine,s to ensure adequate vitamin D intake, along with a vitamin D supplement as sunlight exposure is limited in the winter months.

Zinc

Critical for immune cell communication and repair. Food sources: nuts, seeds, legumes, whole grains, and meats. I often recommend athletes build a daily habit of including nuts and seeds in their diet, such as trail mix for a snack or sprinkling pepitas or hemp seeds on vegetables or pasta to boost daily zinc. I also recommend a weekly habit of red or dark meat to ensure adequate zinc throughout the winter months.

3. Build a Colorful, Plant-Rich Diet

Antioxidants reduce inflammation and strengthen immune defenses.

• berries

• leafy greens

• orange vegetables

• cruciferous vegetables

• herbs and spices

A nutrient-dense diet supports immune recovery after hard training sessions.

4. Stay Hydrated and Support Gut Health

Hydration keeps mucous membranes healthy — your body’s first line of defense. Gut integrity matters too: 70% of immune cells live in the gut. Support your microbiome with fiber and fermented foods such as:

• yogurt (non-dairy options included)

• kefir

• sauerkraut

• kimchi

• high-fiber fruits and vegetables

5. Use Evidence-Based Supplements When Needed

While food should always come first, adding functional foods, herbs, or supplements can help fill nutrient gaps — especially during periods of high training volume or stress. Many athletes will benefit from intentionally adding honey, garlic, or echinacea tea to their diet to boost the immune system during cold and flu season. High-quality, tested immune-boosting supplements could be considered as well. My favorite as a sports dietitian is Previnex Immune Health Plus.

Previnex Immune Health Plus: A High-Quality Supplement for Athlete Immunity

Featured in Episode #246: Supplement Transparency and Trust: Previnex Redefines Industry Standards, Lindsey interviews CEO David Block and discusses why Previnex stands out in a supplement market that often lacks transparency and testing. At minute 34, they dive into the ingredients found in their Immune Health Plus product, which reinforces many of the nutrients discussed so far, plus a few extra!

Here are the core immune-supporting ingredients of Previnex Immune Health Plus, which can be purchased with

15% off using the code CORTES15:

1. Pure Beta-Glucans (from yeast)

Clinically studied to prime the immune system and activate protective immune cells.

2. Organic Mushroom Blend

Includes:

• maitake

• shiitake

• reishi

These mushrooms have long been valued for their antioxidant and immune-modulating properties.

3. Vitamin C (300 mg)

A high-impact dose shown to support immune cell function.

4. Vitamin D3 (25 mcg)

Helps regulate immunity and reduce inflammation.

5. Zinc (10 mg)

Essential for immune repair, recovery, and cellular defense.

6. Elderberry

Rich in flavonols and antioxidants known for supporting immune response during cold and flu season.

7. Calcium

Included to support cellular communication and overall immune function.

The product is built on clinical research, rigorous quality standards, and full transparency — making it an excellent option for athletes aiming to stay healthy while training hard.

Putting It All Together: A Practical Plan for Athletes to Prevent Illness and Strengthen the Immune System

To strengthen your immune system and reduce your risk of illness:

✔ Maintain adequate energy intake

✔ Eat vitamin C–rich fruits and colorful vegetables daily

✔ Prioritize vitamin D and Zinc weekly

✔ Support gut health

✔ Use evidence-based supplements when needed

✔ Prioritize rest, recovery, and hydration

With the right immune-boosting nutrition, athletes can stay healthy, recover faster from the common cold, and keep training consistently throughout the season.