Vitamins are organic compounds necessary for optimal functioning and health in small doses, found both in foods and dietary supplements.
Folic acid can prevent neural tube defects in babies, so all women are advised to start taking multivitamins that contain this vitamin early and throughout their pregnancies.
Vitamin A
Vitamin A is an essential fat-soluble vitamin essential for many bodily processes, including maintaining eye health, supporting organ and immune function, aiding fetal development and providing antioxidant benefits. Vitamin A can be found both in animal and plant foods as well as dietary supplements; micrograms of Retinol Activity Equivalents (RAEs) or percent Daily Value (%DV).
Vitamin A can be found in animal products like liver, fish and dairy foods as well as plant sources like spinach, carrots and cantaloupe. Once consumed, vitamin A is transformed into retinol in the body before being found either preformed (retinyl esters) or as beta-carotene provitamin A carotenoids such as beta-carotene. A deficiency can cause blindness while increasing risks such as measles and diarrhea infections.
Vitamin C
Vitamin C (also referred to as ascorbic acid or L-ascorbic acid) is a water-soluble vitamin found in fruits, berries, vegetables and some meats that is essential to human life and can be taken as dietary supplement. Humans require it for proper functioning and should take ascorbic acid in supplement form for maximum effect; its benefits include production of certain neurotransmitters, collagen fibers and hormones as well as acts as an antioxidant and contributing to immune functioning.
Epidemiological evidence supports that adequate intake of foods containing vitamin C is key in avoiding scurvy. Studies involving cancer patients and healthy controls found no effect of dietary vitamin C consumption on mortality; however, high intakes may increase aluminum absorption from some antacid medications and lead to hypocalcemia.
Large randomized controlled trials have revealed that supplementing with vitamin C has no discernible impact on either the duration or severity of cold symptoms; it merely decreases their frequency. Long-term supplement intakes appear safe when supplemented alongside adequate levels of other vitamins and minerals.
Vitamin D
Vitamin D plays an essential role in controlling calcium metabolism and protecting bone health. Furthermore, studies have linked vitamin D with protection from various cancers, cardiovascular disease, depression and multiple sclerosis.
Vitamin D can be produced naturally through sun exposure and eating certain foods (e.g. fatty fish and beef liver), though fortified foods and supplements also provide this nutrient. When measured in blood, serum 25(OH)D levels are reported as nanomoles per liter or ng/mL.
The Food and Nutrition Board (FNB) of the Institute of Medicine has created RDAs and upper intake limits (ULs) for vitamin D. An adequate or higher 25(OH)D intake might reduce cancer incidence and mortality rates, according to results of clinical trials.
Vitamin E
Vitamin E is a fat-soluble vitamin and antioxidant stored by our bodies in fat tissues and livers, helping protect cells from free radical damage caused by highly reactive chemicals known as free radicals; potentially playing a part in conditions associated with aging; improving immunity; and helping prevent blood clot formation in heart arteries. Found naturally in vegetable oils, cereals, meat, poultry eggs fruit as well as wheat germ oil it’s available both naturally (RRR-alpha-tocopherol) or synthetically (all-rac-alpha-tocopherol).
One small 2019 study suggests that taking vitamin E supplements could improve lung function and asthma symptoms among adults, though larger, long-term studies have produced mixed results; both the GISSI Prevention Trial and the Heart Outcomes Prevention Evaluation Study found no reduction in heart attack risk among people at high risk from taking four years’ worth of vitamin E supplements.
Vitamin K
Vitamin K is a fat-soluble vitamin with many roles in the body that have yet to be fully understood. Notably, its primary functions are blood clotting and bone formation; however, studies have also identified anticalcification, anticancer, and insulin-sensitising benefits of Vitamin K.
Vitamin K exists in various forms that are classified by their repeat of 5-carbon units in their side chain (MK-n). Menadione must first be converted by liver into active menaquinone-4 before cells can use it as food.
Recent research into osteoporosis indicates that higher intakes of vitamin K correlate to increased bone mineral density and reduced hip fracture risk. Vitamin K plays an essential role in carboxylation of osteocalcin to protect bone loss.
