Vitamin Supplements Factsheet – Fat Soluble Vitamins (A, D, E & K)
Vitamins are coenzymes or cofactors required by our body to carry out routine metabolic functions. Recently, people have started realizing the importance of adequate intake, of specific vitamin supplements for their their needs. Here, we would like to establish that any dietary vitamin supplements taken either in combination as a multivitamin or vitamin specific supplement is in fact only an adjunct to one’s intake of vitamins from natural sources, and not a replacement!
Vitamins are basically divided into two categories fat soluble and water soluble. In this article we would like to throw light on the fat soluble ones, which are Vitamin A, D, E and K. These vitamins last longer in our body than the water soluble vitamins as they are stored primarily in the liver and other fatty tissues, utilized only when required, and eliminated rather slowly. Thus, caution must be exercised while consuming these vitamins as supplements as they may lead to toxicity. Learn more about these vitamins and why they are needed.
Vitamin A is an important fat soluble vitamin required for bone growth, tooth development, reproduction, cell division, and gene expression. It also helps maintain moisture of the mucous membranes in the skin, eyes, mouth, nose, throat and lungs. Mild deficiency causes night blindness, diarrhea, intestinal infections, and impaired vision. In severe conditions it causes inflammation of eyes, keratinization of skin and eyes, and blindness in extreme cases.
Who is at Risk of Vitamin A Deficiency
- People with fat malabsorption. Health adults with short term fat malabsorption are not at risk.
- People suffering from celiac disease(a genetic disorder), Crohn’s disease (inflammatory bowel disease, and pancreatic disorders as it interferes with fat absorption.
- Vegans who do not consume enough provitamin A.
Toxicity of Vitamin A
Mild symptoms of toxicity include nausea, irritability, and blurred vision. Severe toxicity results in birth defects, growth retardation, liver abnormalities, enlargement of liver and spleen, loss of hair, bone pain, reduced bone mineral density, increased pressure in skull, skin changes, and centeral nervous system disorders.
Tolerable Upper Intake Levels of Vitamin A
Vitamin D is vital because it helps promote hardening of bones and teeth, and increases the absorption of calcium. Vitamin D deficiency results in ‘rickets’ among children, a condition where the bones become soft and bend. Among adults, it results in osteomalacia, causing bone pain and muscle weakness.
Who is at Risk of Vitamin D Deficiency
- People who do not consume or absorb enough vitamin D from food
- People who have limited exposure to sunlight
- Cases where kidneys cannot convert vitamin D to its active form in the body
- Breastfed infants
- People with dark skin
- People with fat malabsorption disorders like celiac or crohn’s disease
- People who are obese as fat binds with vitamin D, and prevents absorption
Toxicity of Vitamin D
Toxicity occurs only due to supplemental overdose and causes nausea, vomiting, poor appetite, constipation, weakness, and weight loss. It raises blood levels of calcium, and can also cause confusion, disorientation, and problems with heart rhythm. Kidney damage may also occur due to vitamin toxicity.
Tolerable Upper Intake Levels of Vitamin D
The safe upper limit for vitamin D is 1,000 to 1,500 IU/day for infants, 2,500 to 3,000 IU/day for children 1-8 years, and 4,000 IU/day for children 9 years and older, adults, and pregnant and lactating teens and women.
Vitamin E is a strong antioxidant and protects vitamins A and C and fatty acids from oxidation, and also prevents damage to cell membranes. Deficiency of this vitamin is rare, unless a person is starving. In extreme cases it may result in anemia especially in low birth-weight infants.
Toxicity of Vitamin E
Nontoxic under normal conditions, but excessive supplemental abuse may result in nausea, digestive tract disorders. Supplemental high doses of vitamin E might increase the risk of bleeding (by reducing the blood's ability to form clots after a cut or injury) and of serious bleeding in the brain ( hemorrhagic stroke).
Tolerable Upper Intake Levels of Vitamin E
The highest safe level of intake from supplements for adults is 1,500 IU/day for natural forms of vitamin E and 1,100 IU/day in the synthetic form. Children’s needs are lower than adults.
This vitamin is naturally produced by the bacteria in the intestines, vitamin K plays an essential role in normal blood clotting and helps promote bone health. Deficiency may cause severe haemorrhaging. As, newborns lack the bacteria in gut, supplements have to be given to them.
Who is at Risk of Vitamin K Deficiency
- People taking antibiotics/anticoagulants
- People with severe diahrrea
- Tolerable upper limit for this vitamin has not been established.
Vitamin Supplements – Facts you should know
- They are merely supplements not replacements, vitamins are better absorbed in their natural form.
- Always consult your health care practitioner before consuming supplements.
- Food items these days are fortified with fat soluble vitamins. So read nutrition labels carefully, and do not forget to include these when you are calculating you daily vitamin intake.
- Some supplements interact with medicines and over the counter drugs.
- Some supplements can cause complications during surgery
- Always ensure the supplements you are using are legitimate, do not fall for tall claims.
- Ensure from authentic sources if the supplements are safe (eg. FDA)
- In case of adverse reaction consult your physician immediately and also report the supplement directly to FDA