When asked about what nutrient is most important for protecting us from colds and the flu, many people think first of Vitamin C. Indeed, Vitamin C is a recognized star by consumers. Vitamin C is purchased more often than any other nutrient sold for immune function.

Vitamin C has several modes of action. As a cofactor, Vitamin C acts as a catalyst for enzymes involved in the production of collagen, carnitine, and other important compounds in the body. It is also an antioxidant and assists the immune system.

Antioxidants are compounds that are able to capture free radicals and prevent oxidative stress from creating damage to our cells. A free radical electron is one type of damaging particle that is created by exercise, toxins, aging, and general metabolic processes in our bodies. Free radicals are like buckshot coming from a shotgun destroying everything in their path. Within a cell this leads to double stranded DNA breaks, destruction of mitochondria and other critical organelles and makes the body divert resources to repair all the damage that has been caused. As a powerful antioxidant Vitamin C is able to protect cells from these damaging free radicals and also reduce the formation of free radicals in the first place. Vitamin C can also go on to be recycled and repeat the process over and over again. One example of what oxidative stress and free radical electrons can cause is atherosclerosis, or arterial plaque – the main cause of heart attacks and strokes. As an antioxidant, Vitamin C can protect bad LDL cholesterol molecules from turning into a VERY dangerous form of cholesterol called “oxidized LDL” and thus reduce the risk of atherosclerosis and its associated diseases. Apart from its action as an antioxidant, Vitamin C can also help to increase the absorption of iron in the food you eat.

Vitamin C has a direct role in our immune system as well. Specialized white blood cells called neutrophils help protect us from bacteria. When they are exposed to bacteria, neutrophils can rapidly uptake Vitamin C and increase their Vitamin C content by 10-fold. Neutrophils use phagocytosis or ‘cell eating’ as a way to reduce bacterial populations. In the process, free radical electrons are formed. It is believed that the neutrophils use the Vitamin C to reduce or stabilize these free radicals and protect the neutrophil from damage. Organs in the body that are known to concentrate Vitamin C are the liver, spleen, brain, adrenal glands, pancreas, and kidneys. Scientists are still trying to understand exactly why this occurs. Vitamin C is readily absorbed when taken by mouth but absorption decreases as the volume of Vitamin C increases. Only one-half of a 1250 mg dose has been found to be absorbed. This makes food one of your best sources of Vitamin C.

Vitamin C is in many fruits and vegetables. Red bell peppers, kiwi, oranges, and broccoli are all good sources. Vitamin C is heat sensitive and can be destroyed by cooking. So choosing raw fruits and vegetables will deliver the most reliable source of Vitamin C.

In acute illnesses like colds and flu, Vitamin C has been found to help some people. Taking Vitamin C regularly may not help the general public prevent colds. But in physically active people, Vitamin C was found to decrease the number of colds by one half. Studies have shown that exercise can increase the uptake of antioxidants consumed from food. Taking 6-8 grams of Vitamin C daily may shorten the common cold, and some studies indicate that Vitamin C can prevent pneumonia and shorten the duration of hospitalization from pneumonia. While you wouldn’t want to take this much Vitamin C on a regular basis, it might be tolerable in the short run.

Research has increased our understanding of the optimal intakes of Vitamin C. Individuals with higher intakes of Vitamin C have been found to be at less risk for many chronic diseases like cardiovascular disease, cancer, macular degeneration and diseases of the nervous system. The Recommended Daily Allowance (RDA) for Vitamin C was recently increased to 75 mg per day for women and 90 mg per day for men because of the importance to our health. While some people may need more Vitamin C, intakes above 2000 mg (2 grams) is considered the Upper Tolerable Limit (UL). At doses above 2000 mg, Vitamin C can cause gastrointestinal upset including symptoms such as nausea, cramping, and diarrhea.

It’s more important than ever to have a healthy immune system. By using Vessel, you can determine how much Vitamin C your body needs each day and give your body the protection it deserves. Our test strips will analyze how much or how little is being excreted in your urine and calculate a recommended amount to optimize your intake. Head over to our membership page for more details and learn how you can optimize your immune support now.


Key takeaways

  • Daily recommended  dose of Vitamin C is 75 mg per day for women and 90 mg per day for men.
  • Take 6-8 grams of Vitamin C daily may shorten the common cold.

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Reviewed by Dr. Dave Larson