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Vitamin C is known as an essential nutrient for healthy immune function and fighting colds and other infections, but it also plays a vital role in the health of the heart and brain, in healing from injuries, and in pain relief. In all these cases, low blood levels of vitamin C—but not low enough to produce severe signs of deficiency such as scurvy—have a detrimental effect, whereas higher levels are beneficial.
Vitamin C and the Heart
Vitamin C reduces harmful inflammation and helps build collagen and connective tissues that keep organs and blood vessels working well. Numerous studies have found that low levels of the vitamin correlate with more heart disease and deaths.
Most heart attacks are caused by plaque in arteries rupturing and blocking blood flow to the heart. Collagen is one of the building blocks of arteries and it needs to be stable to prevent plaque rupture. Sufficient vitamin C makes collagen more stable and reduces the risk of plaque rupture.
Research at Oregon State University found that people with metabolic syndrome, which increases risks for heart disease and diabetes, need more vitamin C. Metabolic syndrome means having at least three of these conditions: abdominal obesity, high blood pressure, high blood sugar, low levels of “good” HDL cholesterol, and high levels of triglycerides.
“People with metabolic syndrome can eat the same amount of vitamin C as people without metabolic syndrome, but they have lower plasma concentrations of vitamin C,” said Maret Traber, PhD, a professor at Oregon State. It’s estimated that about 35 percent of American adults suffer from metabolic syndrome.
Related: Vitamin C and Skin Health
Vitamin C, Mood, and Mental Function
Measurements of vitamin C in cerebrospinal fluid show that the vitamin is much more concentrated in the brain and nervous system than in the blood, and it influences mental function. Evidence from more than 50 studies shows that higher levels of vitamin C correlate with better memory, concentration, attention, and overall mental function.
This holds true in healthy people, those suffering from minor cognitive impairment, and those with Alzheimer’s disease. Other studies have found that low levels of vitamin C are also related to depression.
Vitamin C Enhances Healing and Reduces Pain
The need for vitamin C increases after injury or surgery, and during illness. Studies show that high-dose vitamin C has improved healing from fractures, joint replacement surgery, anterior cruciate ligament (ACL) reconstruction, and tendon injuries.
Vitamin C enhances formation of collagen and has been found to speed up healing of bones, ligaments, and tendons. It also reduces oxidative stress generated by an injury or illness. Studies have found that high-dose vitamin C reduces the need for opiate medications for pain control. It is useful for reducing pain from shingles, as well as nerve pain, neck pain, back pain, arthritis pain, and other muscle, joint, and bone pain.
Vitamin C is often depleted during hospitalization, and can be severely depleted during some cancer treatments. High-dose vitamin treatment, including intravenous vitamin C, can help relieve treatment-related pain.
Vitamin C Doses
The Recommended Dietary Allowances (RDAs) of vitamin C to prevent deficiency are 90 mg daily for men, 75 mg for women, 85 mg during pregnancy, and 120 mg when breastfeeding. However, scientists at the National Institutes of Health recommended decades ago that the RDA should be increased to 200 mg daily.
Studies of vitamin C to enhance healing from injuries and surgeries found that at least 500 mg daily was beneficial. Specific dosages have not been established for different health conditions, but much higher doses are often used, orally or intravenously, in treatments by health practitioners.
Drugs that Deplete Vitamin C
Three types of drugs have been shown to deplete levels of vitamin C:
Heartburn Drugs: Studies have found that both healthy people and those with H. pylori infection who took omeprazole (Prilosec and similar drugs) for 4 weeks experienced significant drops in vitamin C levels. The drugs likely inhibit the absorption of vitamin C in the stomach.
Aspirin: Studies in the 1970s were the first to find that high-dose aspirin taken for arthritis depleted levels of vitamin C. Later research found that an aspirin dose of 600 mg stopped the absorption of vitamin C by leukocytes—white blood cells in the immune system that fight pathogens. On the other hand, vitamin C may prevent stomach damage from aspirin use.
Birth Control Pills: Some studies have found that vitamin C levels are lower, and levels of harmful oxidation are higher, in women who take birth control pills. Taking vitamin C supplements reduces the oxidative effects of birth control pills.