Vitamins are necessary for healthy development in animals and plants alike, acting as essential dietary components that must be consumed as part of daily meals.
There are eleven water-soluble and four fat-soluble vitamins found in the human body. Water-soluble vitamins leave through urine while excess amounts of fat-soluble vitamins tend to build up in liver tissue and fatty tissues.
Vitamin A
Vitamin A is a fat-soluble vitamin belonging to the retinal family of compounds (vitamin A is its chemical name), supporting healthy teeth, skin, mucous membranes and low light vision in its effects. Furthermore, Vitamin A plays an essential role in immune function as well as growth and development.
Preformed vitamin A can be found in liver, fish and dairy foods; plant sources of it include brightly-colored fruits and vegetables such as leafy greens, yellow and orange vegetables, tomato products and some vegetable oils [1,2]. Our bodies also produce its own form of preformed vitamin A through beta-carotene production; many stand-alone and multivitamin supplements provide either preformed (retinyl palmitate or retinyl acetate) or combination formulations containing both forms (retinyl palmitate or retinyl acetate).
Vitamin A deficiency is relatively rare in the US due to high intakes. However, long-term supplementation may increase your risk of lower respiratory infections.
Vitamin C
Vitamin C is an essential water-soluble antioxidant in human plasma and tissues. It protects important molecules like proteins, lipids (fats), carbohydrates and nucleic acids such as DNA/RNA from damage caused by free radicals produced during normal metabolism or environmental pollutants like tobacco smoke or air pollution, while helping regenerate other important antioxidants like Vitamin E.
Observational studies have suggested an inverse association between serum vitamin C levels and cancer risk. Unfortunately, however, randomized controlled trials have not corroborated this relationship.
Vitamin C could help prevent or treat certain infections, including colds and influenza. It could also shorten recovery times after surgery or trauma injuries by helping heal skin wounds faster or reduce sepsis (blood infections). Supplements containing high doses of Vitamin C are available.
Vitamin D
Vitamin D helps the body absorb calcium for proper bone development and maintenance, helping children avoid rickets and adults avoid osteomalacia. Furthermore, Vitamin D plays an integral role in modulating immunity systems and decreasing inflammation.
The primary indicator of vitamin D status is serum 25(OH)D, which measures both endogenously produced vitamin D as well as those derived from food or supplements. Circulating 1,25(OH)2D has a short half-life that’s tightly regulated by parathyroid hormone, calcium, and phosphate levels.
People living with fat malabsorption conditions like cystic fibrosis, Crohn’s disease, celiac disease and ulcerative colitis require additional sources of vitamin D in their diets. Clinical trials have demonstrated that vitamin D supplements significantly reduced risk for common acute respiratory infections like influenza.
Vitamin E
Vitamin E is a fat-soluble vitamin found in some food products (vegetable oils, nuts and seeds, leafy vegetables and fortified cereals) as well as in supplements. As an antioxidant it protects cells against damage while helping slow the aging process.
Reducing LDL cholesterol oxidation and risk factors has been shown to reduce atherosclerosis risk factors, while further research into its possible effect on Alzheimer’s progression may also be beneficial (further investigation is warranted in this area).
Vitamin E comes in both natural and synthetic forms, with natural alpha-tocopherol being most active. Dietary supplements and some fortified foods often use esterified versions, however once taken by your body they hydrolyze quickly into unesterified vitamin E.
Vitamin K
Vitamin K is an essential fat-soluble vitamin, vital in helping your body produce proteins required for blood clotting and bone building. As such, vitamin K plays an essential role in protecting against osteoporosis while keeping heart health intact.
Phylloquinone, the most prevalent form of vitamin K, can be found in green leafy vegetables and some fermented foods (including soy sauce ). Additionally, bacteria in your digestive tract produce it; vitamin K2 can also be produced within your body from phylloquinone.
Studies suggest that vitamin K could aid in the prevention of arterial hardening, thus decreasing cardiovascular disease risks. More definitive clinical research studies are necessary. Also, vitamin K may interact with some medications (particularly warfarin ), so please check with your healthcare provider prior to taking supplements containing this nutrient.
