Vitamin C and Vitamin D are key vitamins for fighting diseases, with Vitamin C supporting immune cell function and acting as an antioxidant, and Vitamin D regulating the immune system and producing infection-fighting proteins, though Vitamins A, E, and B-complex also play crucial roles in overall immunity. A deficiency in any of these can weaken your body's defenses.
Consuming adequate amounts of several vitamins and minerals—including vitamin A, vitamin C, vitamin D, vitamin E, selenium, and zinc—is important for proper immune function, and clinical deficiencies of these nutrients weaken immunity and can increase susceptibility to infections [2,4,5,8-10].
“Big 3”: Omega-3, Vitamin D3, Probiotics.
Your immune system is a large network of organs, white blood cells, proteins and chemicals. These parts all work together to protect you from germs and other invaders. Your immune system also helps your body heal from infections and injuries.
Antibiotics and Antivirals. Antibiotics are powerful medicines that fight bacterial infections. They either kill bacteria or stop them from reproducing, allowing the body's natural defenses to eliminate the pathogens. Used properly, antibiotics can save lives.
Fever (this is sometimes the only sign of an infection). Chills and sweats. Change in cough or a new cough. Sore throat or new mouth sore.
Although also present in other plant-derived foods, the richest natural sources of vitamin C are fruits and vegetables. Vitamin C is the most widely taken dietary supplement.
Best Multivitamins of 2025
The astaxanthin is known as “the king of antioxidant”, reportedly 800 times stronger than Coenzyme Q10 (CoQ10), 75 times stronger than Alpha Lipoic Acid (ALA) and 6000 times stronger than Vitamin C. Research has discovered that astaxanthin absorbs more free radicals than any other antioxidants.
Five signs of a weak immune system include frequent infections, slow-healing wounds, persistent fatigue, ongoing digestive issues, and getting sick with things that last a long time, like a cold that lingers or severe infections requiring strong treatment. These indicate your body struggles to fight off pathogens or repair itself effectively.
Supplements: What You Really Need
You can also strengthen your immune system by eating well, being physically active, and maintaining a healthy weight. In addition, get enough sleep, don't smoke, and avoid excessive alcohol use. Taking care of yourself will help your immune system take care of you.
Vitamin D helps control the sleep-wake cycle.
One way or another, we know that vitamin D is involved in parts of the brain that regulate sleep timing — including hormones that control the sleep-wake cycle. “For example, vitamin D seems to affect how much melatonin is made in the body.
Folate and vitamins B6 and B12 are required for homocysteine metabolism and are associated with coronary heart disease risk. Vitamin E and lycopene may decrease the risk of prostate cancer. Vitamin D is associated with decreased occurrence of fractures when taken with calcium.
Vitamin A, also known as retinol, produces the pigments in the retina of the eyes. More importantly, it is a vital nutrient for the photoreceptors in your eyes, which determine vision quality in low-light conditions.
Vitamin C. Dietary intake of vitamin C (from food and drinks) is essential, because the human body cannot make this vitamin from other compounds. We also need to have vitamin C as a regular part of our diet because the body cannot store vitamin C for very long.
Vitamin D is used by your body for energy, to support a healthy immune system, and build healthy bones. The body's best source of Vitamin D is produced when your skin is exposed to sunlight, which can be a tricky thing to accomplish at certain times of the year, depending on where you live.
Reasons to use a multivitamin:
I am eating a limited diet or my appetite is poor so that I am eating less than usual. I am following a restricted diet for longer than one week. This could be prescribed such as a liquid diet after a surgical procedure, or a self-imposed diet such as on with the goal of weight loss.
Herbalife is the #1 active and lifestyle nutrition brand in the world. Herbalife is the #1 protein shake in the world. Source: Euromonitor; CH2025ed, active & lifestyle nutrition as weight management & wellbeing, sports nutrition and vitamins & dietary supplements definitions; combined % RSP share GBO for 2024.
Astaxanthin. Astaxanthin is a carotenoid that gives salmon and other seafood their pink color. As an antioxidant, it is 6000 times more potent than vitamin C, 550 times more potent than green tea, and 550 times more potent than vitamin E.
The physician would recommend antiviral therapy to get rid of viruses. The treatment depends on the type of virus and its severity. Antiviral drugs, if given within 2 days after the onset of the symptoms, will prevent the infection and replication of viruses.
Also, infections like the flu virus, mono (mononucleosis), and measles can weaken the immune system for a brief time. Your immune system can also be weakened by smoking, alcohol, and poor nutrition.
Sepsis is a serious condition in which the body responds improperly to an infection. The infection-fighting processes turn on the body, causing the organs to work poorly. Sepsis may progress to septic shock. This is a dramatic drop in blood pressure that can damage the lungs, kidneys, liver and other organs.