Vitamins are organic substances found in small amounts in natural foods and essential for growth and maintaining optimal health.
Fat-soluble vitamins (A, D, E and K) can be stored in liver and fatty tissues and high doses can be toxic; in contrast water-soluble vitamins such as C and the B-complex cannot be stored; any excess amounts are excreted via urine.
Vitamin A
Fat-soluble vitamin A is an essential nutrient, supporting immunity, vision, skin health and reproductive wellbeing. Furthermore, it may reduce cancer risks while encouraging cell division.
Vitamin D is necessary for the formation and maintenance of healthy mucous membranes in your respiratory and intestinal tracts, lungs, and urinary tract. Furthermore, vitamin D promotes cell growth on the surface of your eyes to aid with night blindness vision issues.
Your body can obtain vitamin A through animal products like liver, fish and dairy; plants like carrots, sweet potatoes and leafy greens; as well as preformed vitamin A or provitamin A available as preformed vitamins or dietary supplements.
Vitamin A found in food and supplements may cause liver damage as well as side effects that include dry and itchy skin, headaches, drowsiness and nausea. Pregnant and breastfeeding women should take no more than 10,000 IU per day of preformed vitamin A supplements during gestation or breastfeeding to minimize side effects and complications.
Vitamin D
Vitamin D plays an essential role in maintaining healthy bones. It can be found in many foods, such as cod liver oil, fish (such as salmon, trout and mackerel), egg yolks and fortified milk – as well as being produced naturally through exposure to sunlight; most people can get all of their necessary Vitamin D from sunlight alone.
1,25-dihydroxyvitamin D has been demonstrated to modulate T cells and limit autoimmune responses, while ecological studies have revealed an association between higher prevalences of autoimmune disorders and lower serum 25-hydroxyvitamin D levels, and these prospective studies.
Vitamin D intake or supplementation has long been believed to play an integral part in warding off cancer, heart disease, inflammatory disorders, mood disorders and other serious medical issues. To verify these observations further, large-scale randomized controlled trials must take place.
Vitamin E
Vitamin E is a fat-soluble antioxidant that plays an essential role in protecting against free radical production, immune function, gene expression and cell signaling. You can find vitamin E in many food products like nuts and oils as well as being sold as dietary supplements.
Several observational studies have linked higher intakes of vitamin E with reduced rates of coronary heart disease; however, clinical trials generally fail to verify this correlation.
Studies suggest that vitamin E could play an essential role in helping protect against certain eye diseases, including age-related macular degeneration. More research needs to be conducted in this field.
As high doses of vitamin E may interact with anticoagulant and antiplatelet medications or herbs that reduce blood clotting, thereby increasing bleeding risks, it is wise to consult your physician prior to taking vitamin E supplements. Furthermore, the National Institutes of Health has warned that prolonged use of large doses may increase your risk for prostate cancer.
Vitamin K
Vitamin K is an essential fat-soluble vitamin that plays an integral part in blood clotting and bone metabolism, helping the body regulate calcium levels in its system. If deficiency of vitamin K occurs in women it may result in excessive bleeding as well as menstrual cycle pain during menstruation.
Phylloquinone (vitamin K1) can be found in vegetables. To increase absorption, combine with fatty foods for enhanced absorption. When consumed, bacteria in the gut transform phylloquinone to longer chain vitamins known as menaquinones (MK-4 through MK-13).
One observational study demonstrated a link between higher intakes of phylloquinones and menaquinones with decreased cardiovascular disease mortality; another study did not find such an inverse association; nonetheless several other studies have linked low vitamin K consumption with age-related bone loss and cognitive decline, and low MK-2 intake. Studies suggest this form of vitamin K could provide protection from cancer growth by suppressing genes responsible for its formation (79).
