Best Supplements for Immune Health (11 min.)

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Summary:
The best supplements for immune health start with a high-quality multivitamin and a daily probiotic†. Adding targeted nutrients like the B vitamins for energy, vitamin C for immune defense, vitamin D for immune regulation, magnesium for stress balance, zinc for immune cell development and iron (if needed) for oxygen transport can help keep defenses strong†. For extra support, options like quercetin for antioxidant protection, omega-3s for inflammatory balance, ashwagandha for stress resilience, l-lysine for tissue health, melatonin for restful sleep, and magnesium L-threonate for cognitive calm can give you an individualized immune health plan that fits your lifestyle year-round†.

Table of Contents

• Start with the Foundation
  • Multivitamins: Comprehensive Immune Support
    • B Complex — Cellular Energy and Immune Coordination
    • Vitamin C — Immune Cell Defender
    • Vitamin D — Immune Regulator and Respiratory Defense
    • Magnesium for Immune Health and Stress Management
    • Zinc — The Immune Builder
    • Iron for Immune Support
  • Probiotics: Gut Health and Immunity
  • If You’re Not Taking a Multivitamin
• Extra Credit for Immune Health
  • • Quercetin Complex for Immune Support and Antioxidant Protection
    • Omega-3 Fatty Acids for Immune and Inflammatory Balance
    • Ashwagandha for Stress Management and Immune Support
    • L-Lysine for Immune Function and Tissue Health
• Sleep and Immune Health
  • Melatonin for Sleep and Immune System Strength
  • Stress, Sleep, and Magnesium L-Threonate – Cognitive Health
• Final Thoughts

Your immune system tirelessly toils around the clock, working to defend against everyday challenges. Even the healthiest lifestyle can sometimes benefit from extra nutritional support†. For more than 55 years, Kenneth H. Cooper, MD, MPH, has inspired people around the world to take charge of their health through exercise, nutrition, rest, and stress management, all key parts of immune balance†. His Get Cooperized® 8 Healthy Steps includes Step 4: “Take the right supplements for you,” a simple way to keep your defenses strong year-round†.

Below, explore how to build a reliable supplement foundation, add targeted support, and create your individualized immune health strategy using physician-recommended products from Cooper Complete, the best supplements for immune health†.

Start with the Foundation

Multivitamins: Comprehensive Immune Support†

A high-quality multivitamin ensures you get the daily baseline of vitamins and minerals your immune system needs to function at its best†. Cooper Complete multivitamins are physician-formulated to fill common nutrient gaps, using high-quality, bioavailable ingredients and clinically relevant doses.

• Original Comprehensive Multivitamin (Iron-Free or With-Iron): Twice-daily formula providing a robust antioxidant blend with 500 mg of vitamin C, all the B vitamins (in their activated forms), 50 mcg (2000 IU) of vitamin D3, and comprehensive mineral support†. Ideal for those who want higher nutrient levels.
• Basic One Multivitamin (Iron-Free or With-Iron): One-tablet-per-day convenience with 150 mg of vitamin C, 50 mcg (2000 IU) of vitamin D3, and solid mineral support†. Perfect for those seeking simplicity without sacrificing quality.

B Complex — Cellular Energy and Immune Coordination†

B vitamins work synergistically to support immune cell production, antioxidant defense, and stress resilience†:

• B1 (Thiamin): Converts food into usable energy for immune activity†.
• B2 (Riboflavin): Protects immune cells from oxidative damage†.
• B3 (Niacin): Aids DNA repair and supports normal inflammatory balance†.
• B5 (Pantothenic Acid): Helps synthesize adrenal hormones that modulate immunity†.
• B6 (Pyridoxine): Required for white blood cell production and antibody formation†.
• B7 (Biotin): Maintains skin and mucous membranes, the body’s first line of defense (Original multivitamin).
• B9 (Folate (Quatrefolic®)): Required for DNA synthesis and the production of white blood cells, folate plays a vital role in both innate and adaptive immune responses†.
• B12 (activated methylcobalamin form†): Supports the formation of red blood cells that deliver oxygen to immune tissues and helps maintain healthy nerve function for optimal immune signaling†.

(Standalone option: Cooper Complete Advanced B Complex.)

Vitamin C — Immune Cell Defender†

Vitamin C’s connection to immune health first entered the public spotlight in the 1970s when two-time Nobel Prize winner Linus Pauling wrote Vitamin C and the Common Cold and proposed that high doses could help prevent and shorten the common cold†. While Pauling’s recommendations were controversial, his work inspired decades of scientific research. Modern studies, including work by Harri Hemilä and colleagues, show that vitamin C supplementation (typically ≥200 mg per day) does not appear to reduce the overall number of colds in the general population but can modestly shorten the duration and reduce symptom severity†. In people under heavy physical stress, like marathon training, skiers, and military personnel, vitamin C has been shown to cut the risk of catching a cold by about half†. Laboratory studies also demonstrate that vitamin C accumulates in white blood cells, enhancing their ability to combat pathogens and reducing oxidative stress†. Together, the evidence suggests vitamin C plays a valuable role in supporting immune defenses, particularly during times of increased physical or environmental stress†.

(Standalone option: Natural Vitamin C with citrus bioflavonoids and rose hips for enhanced absorption, ideal for marathon runners and other extreme athletes†.)

Vitamin D — Immune Regulator and Respiratory Defense†

Vitamin D plays a key role in immune defense, helping the body mount an appropriate response to everyday challenges†. Research suggests that people with healthy vitamin D levels are more likely to maintain healthy immune function and respiratory well-being than those with low vitamin D levels†.

A large meta-analysis in the British Medical Journal reviewed 25 randomized clinical trials involving more than 11,000 participants. It concluded that vitamin D supplementation is safe and protective against acute respiratory tract infections overall†. The most significant benefits were observed in people with the lowest vitamin D levels and in those taking daily or weekly doses rather than occasional large amounts†.

For those who need additional support beyond the amount in a multivitamin, Cooper Complete offers standalone Vitamin D3 supplements in 25 mcg (1000 IU) drops, 25 mcg (1000 IU) softgels, and 125 mcg (5000 IU) softgels to support individualized needs.

Magnesium for Immune Health and Stress Management†

Magnesium works quietly behind the scenes in more than 300 biochemical reactions in the body, many of them essential for immune function†. It helps activate white blood cells, modulates inflammation, and supports infection-fighting antibody production†. Without enough magnesium, the immune system can become less responsive†.

Since stress and poor sleep can further strain immune defenses, magnesium’s calming effects make it a valuable double-duty nutrient. Cooper Complete offers:

• Cognitive Health (Magnesium L-Threonate), which supports relaxation and sleep quality†
• Magnesium Glycinate, gentle, highly absorbable support for whole-body health†

Zinc — The Immune Builder†

Zinc is an essential mineral, which means the body requires it for life, but cannot produce it on its own. Zinc plays a critical role in immune function, wound healing, and cellular repair†. It supports the development and activation of immune cells, helps maintain healthy skin and mucous membranes as barriers against pathogens, and functions as an antioxidant to protect cells from oxidative stress†. Research shows that adequate zinc intake can reduce the duration and severity of colds when taken at the onset of symptoms†.

Like iron, too much zinc can be harmful. Taking more than 50 mg of zinc per day over the long term can be harmful, potentially leading to copper deficiency, impaired immunity, and other health issues†. All Cooper Complete multivitamins contain 15 mg of zinc. A standalone Zinc Supplement has 25 mg of zinc per pill.

Iron for Immune Support†

Iron is essential for oxygen transport, energy production, and immune cell function†. Iron deficiency is one of the most common nutritional deficiencies worldwide and can weaken immune response, making it harder for the body to fight illness†. In the United States, it’s more common for some groups of people to struggle with having healthy levels:

• Girls and women who have heavy periods
• Frequent blood donors
• People with gastrointestinal disorders
• Those with heart failure
• Individuals living with cancer
• Vegans and vegetarians
• Those following a plant-based diet

It’s important to keep in mind that not everyone needs supplemental iron. In fact, too much iron can be harmful. Talk with your physician or health care provider about your particular circumstances and have your blood tested to determine whether you might benefit from a multivitamin with iron, or supplemental iron†.

Probiotics — The Gut–Immune Connection

Roughly 70% of your immune system resides in your gut, making digestive health a cornerstone of immune defense†. Probiotics, which are beneficial bacteria, help keep this ecosystem balanced, support nutrient absorption, and fine-tune immune communication†.

When it comes to supporting gut balance and immune health†, Cooper Complete Advanced Daily Probiotic combines scientifically studied probiotic strains to help maintain everyday balance and overall wellness:

• Saccharomyces boulardii – A probiotic yeast known for its unique ability to help maintain a healthy intestinal environment, it helps keep the gut in balance and strengthens the gut lining†
• Lactobacillus acidophilus La-14 – Encourages good bacteria growth and helps the immune cells respond effectively†
• Bifidobacterium longum Bi-05 – Supports a healthy mix of bacteria in the gut, which can help the body stay resilient against daily stressors†
• Lactiplantibacillus plantarum Lp-115 – Helps protect the intestinal lining and supports a balanced immune response†
• Bifidobacterium lactis HN019 – Shown in research to help regulate immune cell activity and promote overall immune health†

Each vegetarian capsule is protected with nitrogen-sealed blister packaging to preserve potency and engineered to survive stomach acid, ensuring these beneficial strains reach the small intestine where they do their best work†.

If You’re Not Taking a Multivitamin

If you prefer to skip a multivitamin, consider this immune-support starter set:

• Advanced B Complex
• Natural Vitamin C
• Vitamin D
• Advanced Daily Probiotic
• Zinc Supplement 25 mg

Extra Credit for Immune Health

While a daily multivitamin and probiotic form a strong foundation for immune support†, there are other supplements that can provide targeted benefits. Depending on your individual health goals, adding one or more of these nutrients may help support a balanced immune response, promote overall wellness, and address specific areas such as stress, sleep, or seasonal challenges†.

Quercetin Complex for Immune Support and Antioxidant Protection†

Quercetin is a plant-based flavonoid found in apples, onions, and berries that supports immune health by helping protect cells from oxidative stress and assisting the body in managing normal inflammation†. Bromelain, a natural enzyme from the fibrous core of the pineapple, complements quercetin by supporting healthy inflammatory balance and aiding nutrient absorption†. Together, these compounds offer targeted seasonal immune support and antioxidant protection†.

Cooper Complete Quercetin Complex may be a good choice for those who want extra antioxidant protection, support for seasonal immune challenges, or a way to bolster the body’s natural defenses†.

Omega-3 Fatty Acids for Immune and Inflammatory Balance†

Omega-3 fatty acids, found naturally in salmon and other fatty fish, are structural components of every cell in the body, including immune cells†. They help maintain fluidity of cell membranes, which allows immune cells to respond efficiently†. Omega-3s also help temper excess inflammation, the body’s normal defense mechanism that can be harmful if it persists too long†.

Since most people don’t eat enough fatty fish to meet their needs, Omega-3 supplements are an effective way to boost levels of EPA and DHA, the long-chain omega-3s that research links to balanced immune function and overall health†.

Ashwagandha for Stress Management and Immune Support†

Ashwagandha is an adaptogenic herb that helps the body adapt to stress, which is important because chronic stress can weaken immune defenses, making it harder for the body to stay resilient†. (Adaptogens are natural substances, usually from plants or herbs, that help the body adapt to everyday stress and maintain balance, supporting overall well-being†. They’re thought to work by supporting the body’s stress-response system, helping the body respond more effectively whether the stress is physical, mental, or environmental.) By promoting calmness and reducing the effects of ongoing stress, ashwagandha may help the immune system function more effectively†.

Cooper Complete Ashwagandha is a smart choice for those who face constant stress, want to promote emotional balance, or are looking for a natural way to help keep the immune system strong†.

L-Lysine for Immune Function and Tissue Health†

L-Lysine is an essential amino acid; the body can’t make it, so it must come from food or supplements. It supports immune health by helping produce antibodies, the proteins that respond to immune challenges†. L-Lysine also plays a role in collagen production, which is vital for healthy skin, bones, and connective tissues, all part of the body’s first line of defense†. This role in collagen formation makes L-lysine beneficial for wound healing, as it helps repair damaged tissues and support healthy skin.

Cooper Complete L-Lysine supplement contains 1,500 mg of L-Lysine in each daily serving of 3 pills, making it a great option for those who want to support immune resilience, promote tissue repair, or maintain skin integrity as part of their overall wellness routine†.

Sleep and Immune Health†

Good sleep is one of the most important things you can do for your immune system†. When you don’t get quality rest, your body produces fewer infection-fighting white blood cells and antibodies, reducing the body’s ability to maintain strong immune defenses†. Consistent, restorative sleep helps your immune system stay balanced, respond effectively to life, and recover faster when you’re not feeling your best†.

Melatonin for Sleep and Immune System Strength†

Melatonin is a natural hormone that signals the body that it’s time to rest, making it easier to fall asleep and stay asleep†. The body typically starts producing melatonin in the evening about two hours before bedtime, triggered by lower light levels†. (This could be well after sunset in the summer, or before sunset in the winter, depending on the season and your sleep schedule.) Taking Cooper Complete Low-Dose Melatonin at this time, rather than right before bed, can help align with your body’s natural rhythm for better rest†.

Because good sleep is linked to stronger immune defenses, melatonin can be a helpful option for occasional sleeplessness or adjusting to new sleep schedules†. For ongoing sleep issues, talk with a sleep medicine physician for a comprehensive evaluation to identify underlying causes.

Stress, Sleep, and Magnesium L-Threonate — Cognitive Health†

Magnesium L-Threonate is a unique form of magnesium in that it can cross the blood-brain barrier, helping to support calm thinking, mental clarity, and, importantly, deeper rest†. Since quality sleep and lower stress are both essential for a healthy immune system, this nutrient can be a valuable addition for those looking to improve both mind and physical health†. Taking Cognitive Health Magnesium L-Threonate supplement at night might help you feel more relaxed, and rest more deeply throughout the night†.

Final Thoughts

Start with the basics, a quality multivitamin and probiotic†, and add targeted nutrients to match your needs. Whether you’re navigating seasonal changes, managing stress, or sleep challenges, Cooper Complete offers supplements to help keep your immune system ready year-round†.

Pair smart supplementation with Dr. Cooper’s Get Cooperized® 8 Healthy Steps for a balanced, sustainable approach to immune health†.

For more, read Supporting a Healthy Immune System with Ryan Harris, MD, from Cooper Clinic.

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About the Author: Jill Turner is the President of Cooper Complete® Nutritional Supplements, where she oversees product development and customer experience. She enjoys writing about vitamins, supplements, and preventive health to help consumers make informed, science-backed decisions.

Cooper Complete August 13, 2025