Vitamins are essential nutrients that keep the body healthy by participating in several important metabolic pathways which are very essential for maintaining healthy bones, brain, skin and even blood. All the vitamins needed cannot be produced by the body and many need to be obtained from food and also by supplements in many cases.
This has resulted in many things we buy for consumption like bottled water, mineral water, fruit juices and even cereals and flour etc often fortified by vitamins.
It is quite possible that having too much of them can lead to health hazards. This is also called hypervitaminosis or vitamin toxicity.
Different Vitamins needed by the body:
Vitamin A, Vitamin B1 (Thiamin), Vitamin B2 (Riboflavin), Vitamin B3 (Niacin), Vitamin B5 (Pantothenic Acid), Vitamin B6, Vitamin B7 (Biotin), Vitamin B9 (Folic acid), Vitamin B12(cobalamin), Vitamin C (Ascorbic acid), Vitamin D (Calciferol), Vitamin E (alpha-tocopherol), Vitamin K (menadione).
Determinants of developing Vitamin Toxicity:
One of the important determining factors is whether the vitamin is water soluble or fat soluble. It is the fat-soluble vitamins which are taken up by the fat in the body tissues and remain there for very long periods. On the other hand, water soluble vitamins get digested and are not absorbed in any body tissue for any length of time. Only fat-soluble vitamins out of the list are Vitamins A, D, E and K which can remain within fat deposits for long time.
Water soluble vitamins:
B1 (Thiamine)
Mutton, beef, eggs, whole grain, nuts and sunflower seeds are rich sources. Recommended daily intake is 1.2 mgs for men and 1.1for women. It has not been reported to have toxic effects in high doses.
Vitamin B2 (Riboflavin)
Rich sources are dairy products, eggs, meat, salmon, whole grains, and leafy green vegetables. The recommended daily amount for adults is 1.3 mg for men and 1.1 mg for women. It has not been shown to be toxic in high doses.
Vitamin B3 (Niacin)
Rich sources are meat, fish, whole grains, and leafy greens. The recommended daily amount for adults is 16 mg for men and 14 mg for women. It was being used to manage high cholesterol especially the very atherogenic molecule called Lp(a). However large randomized clinical trials did not show any benefits. It also increases uric acid hence patients with gout should not take it. In addition, when combined with statin group of drugs which are the most commonly used agents for reducing bad cholesterol these are known to produce skeletal muscle toxicity. It can also worsen peptic ulcer disease. Its overdosage can lead to liver damage especially in patients with pre-existing liver disease.
Vitamin B5 (Pantothenic acid)
Its sources are chicken, egg yolks, dairy products , whole grains, legumes, mushrooms, cabbage, and broccoli. The recommended daily amount for adults is 5 mg. It has not been shown to be toxic in high doses, but in extreme doses may cause diarrhoea.
Vitamin B6
Vitamin B6 is a group of compounds related to pyridoxine, which is found in poultry, fish, whole grains, legumes, and blueberries. The recommended daily amount is 1.3 mg–2 mg for adults. Supplemental doses over 100 mg per day are not recommended for adults outside of therapeutic applications. Extreme doses of 1,000 mg–6,000 mg taken over an extended period of time can negatively affect the brain, creating neurological symptoms like numbness and tingling in the extremities.
Taking too much may cause loss of coordination, skin lesions, and disrupted digestion. The symptoms usually resolve when the vitamin supplements are discontinued.
Vitamin B7 (Biotin)
Rich sources are liver, eggs, dairy, banana, sweet potato, and nuts. The recommended daily amount for adults is 30 mcg. It has not been shown to be toxic in high doses.
Vitamin B9 (Folate, Folic Acid)
It is important for new cell production as well as early brain and spine development of a foetus during pregnancy. It is found in citrus and leafy greens. The recommended daily amount for adults is 400 mcg. Pregnant and lactating ladies should get 500 to 600 mcg, Folic acid is not generally toxic in high doses
Vitamin B12 (Cobalamin)
This vitamin is also known as Cobalamin and is found in dairy, eggs, fish, poultry, and meat. The recommended daily amount for adults is 2.4 mcg. Pure vegetarians often have deficiency of it and can lead to anaemia. It has not been shown to be toxic in high doses
Vitamin C (Ascorbic Acid)
It is used by the body as an antioxidant to prevent damage to cells and also for the growth and repair of tissues in the body. It is found in citrus fruit, potatoes, peppers, and greens. The recommended daily amount for adults is 90 mg for men and 75 mg for women. It is not normally considered toxic, but large doses of 2,000 mg per day can affect digestion, causing diarrhoea, cramps, and nausea. Very high doses as frequently taken during colds, fevers have no additional benefits.
Fat Soluble Vitamins (Vitamins A, D, E and K)
Vitamin A:
It is used by the body to promote vision, increase immunity and for normal body functions in several biochemical pathways. It is found in high concentrations in animal liver, kidney, and fish oil, and in moderate concentrations in dairy and eggs. Vegetables such as sweet potatoes and carrots are also moderate sources of vitamin A. Animal based sources give readymade vitamin however sources like carrots contain it in a pro-active form needing liver to convert it into active molecule.
The daily maximum dose is around 10,000 international units. Its supplements should be strictly avoided by pregnant ladies and even those planning to conceive. It can have teratogenic effects on the foetus.
High dose intake can occur in persons who consume plenty of eggs, dairy products and also take vitamin A supplements to promote health risk of getting toxicity if taken for prolonged periods. A group of medicines called retinoids (acitretin, alitretinoin and tazarotene etc used to treat several skin conditions including acne and psoriasis. if taken with high doses of Vitamin A can lead to overdosage and toxicity.
If taken in higher doses it commonly affects the skin causing peeling, reddening, visual disturbances, bone pains, migraine like headache, and serious problems like increased intra cranial pressures leading to even coma and death.
Vitamin D (Calciferol)
An important vitamin which is needed for calcium absorption and important for bone formation. Its precursor is produced by skin under the influence of sunlight. For this reason, its deficiency is common because exposure to sunlight is very limited, people spending most time indoors. It is available as a supplement in fortified milk, fortified juice, cereal, and fish and is available as a supplement.
The daily requirement is 600 to 800 IU’s. Smaller dose in younger people and higher in elderly. Taking it in higher doses (more than 1000 I Us per day) for long periods can lead to toxicity. This leads to very high calcium levels in blood leading to kidney stones, recurrent vomiting, tendency for bone fractures etc. diagnosis can be confirmed by assessing blood or urine levels for vitamin D and calcium.
Vitamin E (alpha-tocopherol)
it is a vitamin which protects cell damage. Vegetable oils, fish, nut, wheat and green leafy vegetables are rich sources. Daily need is 15mg.
it is often used to reduce increased triglyceride levels and as a treatment of fatty liver in doses of 400 mgs per day. Fish oils (Omega 3 fatty acids should be preferred) along with very low carbohydrates in diet. Too much of Vit E for long periods can lead to bleeding and haemorrhagic strokes etc and should be avoided.
Vitamin K (Menadione)
This vitamin is important for blood clotting. Rich sources are milk, green leafy vegetables. Recommended daily dose is 90 mcg for women and 120 mcg in men. It should be in avoided in patients taking anti-coagulants like warfarin and acitrom as it antagonizes their actions.
Tailpiece:
Vitamins are important agents for maintaining the metabolism for healthy body functioning. These agents are best consumed from natural sources which are available in plenty. Taking tablets and capsules in high doses and multiple fortified food items is not the answer. Good things taken in excessive amounts do not multiply their benefits on the other hand can lead to serious toxicities.
Prof Upendra Kaul, Founder Director Gauri Kaul Foundation
Disclaimer: The views and opinions expressed in this article are the personal opinions of the author.
The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK.