THE NITTY GRITTYGiven vitamin C’s antioxidant benefits, as well as its immune-boosting power and collagen production, it’s not surprising that this nutrient has been shown to support a wide number of health conditions, everything from colds and immunity to cataracts and heart health. Let’s take a look at each of these.
Common ColdVitamin C plays a large role in the health of the immune system. It stimulates the production and function of white blood cells1 and promotes an antiviral effect in humans.2 Research shows that high-dose vitamin C supplementation decreases the duration and severity of the common cold. In one study, researchers found that 26% of children who took 2,000 mg of vitamin C daily saw a decrease in cold duration.3 Additionally, the dose matters, with at least 2,000 mg daily having a more significant effect, as compared to 1,000 mg daily.3 Similarly, in a study of 252 adult subjects with a cold or flu, those who were given 1,000 mg of vitamin C hourly for the first six hours, followed by times a day thereafter enjoyed an 85% decrease in cold and flu symptoms, as compared to those participants who were treated with pain relievers and decongestants.4
CataractsOptimum vitamin C levels are associated with a decreased risk of cataracts, while low vitamin C levels are connected to an increased risk of the disease.5-8 Research suggests that you’d have to take at least 300 mg a day for several years to see a protective benefit.9
Heart DiseaseVitamin C supplementation has been found to support heart health in some areas, including cardiovascular disease, stroke, and blood pressure. In the First National Health Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, researchers found that the risk of death from cardiovascular diseases was 42% lower in men and 25% lower in women who had a total daily vitamin C intake of about 300 mg per day.10-11 Similarly, the Nurses’ Health Study showed that taking at least 360 mg of vitamin C from a combination of food and supplements or supplements alone was associated with a 27-28% reduction in coronary heart disease risk.12 When it comes to stroke, researchers learned that people with the highest blood levels of vitamin C had a 29% lower risk of stroke than those with the lowest levels of vitamin C.13 This was also seen in a study of 20,649 adults in the U.K., which found that those with the highest levels of vitamin C had a 42% lower risk of stroke compared to those with the lowest levels.14 Finally, vitamin C’s ability to repair connective tissue and cartilage contribute to healthy blood vessels, preserving what doctors refer to as the "integrity of the vascular wall." This was seen in two different studies, which found that taking 500 mg of vitamin C daily can decrease systolic blood pressure. In the first study, a patient who took the vitamin for six weeks enjoyed a 1.8 mm Hg decrease in systolic blood pressure by 1.8 mm Hg.15 In the second study, just four weeks of supplementation yielded a nine percent reduction in systolic blood pressure.16
References: 1. Anderson R, et al. Am J Clin Nutr. 1980;33(1):71-6. 2. Sasazuki S, et al. Eur J Clin Nutr. 2006;60(1):9-17. 3. Hemila H. Med Hypotheses. 1999;52(2):171-8. 4. Gorton HC, Jarvis K. J Manipulative Physiol Ther. 1999;22(8):530-3. 5. Jacques PF, et al. 2001;119(7):1009-19. 6. Yoshida M, et al. Eur J Nutr. 2007;46(2):118-24. 7. Simon JA, Hudes ES. J Clin Epidemiol. 1999;52(12):1207-11. 8. Dherani M, et al. Invest Ophthalmol Vis Sci. 2008;49(8):3328-35. 9. Peerapatdit T, et al. J Med Assoc Thai. 2006;89 Suppl 5:S147-55. 10. Enstrom JE, et al. Epidemiology. 1992;3(3):194-202. 11. Enstrom JE. Nutr Today. 1993;28:28-32. 12. Osganian SK, et al. J Am Coll Cardiol. 2003;42(2):246-52. 13. Yokoyama T, et al. The Shibata study. Stroke. 2000;31(10):2287-94. 14. Myint PK, et al. Am J Clin Nutr. 2008;87(1):64-9. 15. Ward NC, et al. J Hypertens. 2005;23(2):427-34. 16. Duffy SJ, et al. Lancet. 1999;354(9195):2048-9.