Vitamin D plays an essential role in several systems of the human body, from its function in calcium and phosphorus metabolism, to modulation of the immune system and reduction of risk of cardiovascular diseases (Grober et al. 2013). Unfortunately, factors such as diet, geographic location, and skin pigmentation contribute to an increase in the prevalence of vitamin D deficiency worldwide, leading to a higher rate of associated diseases. Cardiovascular diseases such as coronary heart disease (CAD), hypertensive vascular disease, and myocardial infarction have been shown to be more common in people with lower levels of vitamin D in their system (Lavie, Lee & Milani 2011). Vitamin D can often be obtained with two different methods. The main method is the conversion of 7-dehydrocholesterol in the skin to vitamin D3 via exposure to sunlight to absorb ultraviolet B radiation with a wavelength of 290–315 nm (Holick 2007). The other method is to consume plants in diets in the form of vitamin D2; or fatty fish, supplements or products fortified with vitamin D in the form of vitamin D3 (Lavie, Lee & Milani 2011). Vitamin D undergoes hydroxylation twice; first with the enzyme 25-hydroxylase to form 25-hydroxyvitamin D (Calcidiol) (Al Mheid et al. 2013). Then, calcidiol is converted to the most active form of vitamin D, the hormone 1,25-dihidroxyvitamin D (calcitriol), using renal 1--hydroxylase in the kidney (Al Mheid et al. 2013). Vitamins D2 and D3 are relatively similar since they share the same hydroxylation pathway to produce calcitriol (Tripkovic 2013). However, D3 has been shown to have a greater influence on calcidiol levels and is therefore more effective in maintaining vitamin D health (Heaney et al. 2011). .C...... middle of article......, RL & Armas, LAG 2011, “Vitamin D3 is more potent than vitamin D2 in humans”, The Journal of Clinical Endocrinology & Metabolism, vol. 96, no. 3, pp. E447-E52.Holick, MF 2007, “Vitamin D deficiency”, New England Journal of Medicine, vol. 357, no. 3, pp. 266-81.Lavie, CJ, Lee, JH & Milani, RV 2011, “Will vitamin D and cardiovascular disease live up to the hype? », Journal of the American College of Cardiology, vol. 58, no. 15, pp. 1547-56. Reid, IR & Bolland, MJ 2012, 'Role of vitamin D deficiency in cardiovascular disease', Heart, vol. 98, no. 8, pp. 609-14.Tripkovic, L 2013, “Vitamin D2 versus vitamin D3: are they one and the same thing? », Nutrition Bulletin, vol. 38, no. 2, pp. 243-8. Zittermann, A 2006, 'Vitamin D and disease prevention with special reference to cardiovascular diseases', Progress in Biophysics and Molecular Biology, vol. 92, no. 1, p.p... 39-48.