Vitamins are essential or vital nutrients for our body but in limited amounts. Vitamin cannot be synthesized in our body and so must be obtained from external or dietary sources.
Vitamins play an important role in various physiochemical metabolisms, so vitamin deficiency may cause severe illness or developmental defects like beriberi caused by the deficiency of vitamin B1, scurvy caused by the deficiency of vitamin C, rickets caused by the deficiency of vitamin D, night blindness caused by the the deficiency of vitamin A and many other diseases.
To overcome the deficiency of vitamins we often take vitamin supplements; but excessive amount of vitamins may be harmful.
High storage level of vitamins is called hypervitaminosis or vitamin poisoning. Hypervitaminosis often shows toxic symptoms. Generally normal diet don’t cause hypervitaminosis. However, the normal American diet usually lacks is adequate nutrition, therefore supplements are important to take. The old saying ” A little is good, a lot is better” is not always the best advice because the most common cause of hypertitaminiosis is excessive supplement intake.
High amounts of fat soluble vitamins (Vitamin A, vitamin D, vitamin E and vitamin K) may cause hypervitaminosis because they remain stored in human body. The excess amount of water soluble vitamins (vitamin C and vitamin B complex) is generally excreted through urine.
Fat soluble Vitamins
Vitamin A or Retinol is an important vitamin, necessary for overall growth, development and proper eyesight. But the excess storage of vitamin A causes vitamin A poisoning.
In most cases the cause of hypervitaminosis A is the taking of high-dose dietary supplements. The excess amount of vitamin A is stored in liver but when the maximum level exceeds then symptoms of vitamin poisoning is seen.
The natural sources of vitamin A are yellow or orange vegetables like carrot, pumpkin, mango, papaya etc. Liver of beef, pork, chicken and turkey are also good sources. Cod liver oil is the highest natural source of vitamin A (30000 μg/ 100gm).
The dose for Vitamin A should be around 10,000 units per day. However, doses up to 25,000 iu are tolerated well. Beta-carotine is a precursor to vitamin A and a daily dose of 25,000 iu daily is recommended to improve your Vitamin A level. One should avoid doses over this level to decrease the risk of hypervitaminosis.
Hypervitaminosis A is of two types –
1. Chronic : Chronic hypervitaminosis A happens when very high amounts of vitamin A ingested for a long period of time. The symptoms of chronic hypervitaminosis A are irritability, drowsiness, abdominal pain, nausea and vomiting.
2. Acute : Acute poisoning of vitamin A generally happens after consuming large amounts of vitamin A over a short period of time. The symptoms are blurry vision, dizziness, bone pain, reduced bone density causing osteoporosis, poor appetite, nausea and vomiting, liver problems, cracked fingernails, mouth ulcers, yellowed skin, hair loss etc
The most effective way to treat hypervitaminosis A is to stop taking the supplements containing high doses of vitamin A. But in case of liver or kidney damage or osteoporosis, proper medical treatment is required.
Hypervitaminosis D : Vitamin D or Calciferol mainly helps in bone development. The hypervitaminosis D can theoretically cause an increased level of blood calcium causing hypercalcemia. Hypercalcemia may often lead to over calcification of bone and cartilage. Contrary to common believe, hypervitaminosis D is not due to excessive exposure to sunlight. Megadoses of vitamin D supplementations is the real cause behind vitamin D poisoning.
However, normal serum levels of Vitamin D have now been shown to be enough. Studies have proven that higher serum levels of Vitamin D (over 50 ng/ml) have been associated with a decreased risk of multiple cancers, less heart disease and protective for Alzheimer’s disease.
The natural sources of vitamin D are as follows : Mushroom Agaricus bisporus is a huge source of vitamin D2 or Ergocalciferol. Fatty fish species like salmon, mackerel, cat fish, sardines and tunas are good sources of vitamin D3 or Cholecalciferol. Alfalfa (Medicago sativa subsp. sativa) is a very good source of both Ergocalciferol and Cholecalciferol.
The recommended dietary requirement of vitamin D can be as high as 10,000 iu per day, although most people can acheive a good blood level taking 3,000 iu to 5,000 iu per day.
The main symptoms of hypervitaminosis D is irritability, fatigue, muscular weakness, decreased appetite, dehydration, vomiting, constipation poly urea, tetany etc. Other symptoms include High blood pressure and kidney stone.
Hypervitaminosis E : Vitamin E or α- β- γ- and δ-tocopherols mainly acts as antioxidants. Vitamin E also helps in inhibition of platelet aggregation and acts as an anticoagulant. Hypervitaminosis E causes increased bleeding due to the inhibition of vitamin K-dependent carboxylase.
The sources of vitamin E are various oils like sunflower oil, leafy green vegetables like spinach and some fruits like mango and papaya.
The recommended daily upper tolerable intake level of vitamin E is 1,000 mg.
Someone suffering from this condition will bleed more with a cut or wound, as Hypervitaminosis E reduces the action of vitamin K.
Water soluble vitamins
Hypervitaminosis B6: Vitamin B6 or Pyridoxine plays an important role in various metabolisms like neurotransmitter synthesis, histamine synthesis, haemoglobin synthesis and gene expression. So overdose of vitamin B6 may cause various kinds of neurological disorders.
The source of Vitamin B6 are numerous – whole grain cereals, meats and vegetables.
The recommended dietary requirement of vitamin B6 is 200-400 mcg per day, but doses up to 800 mcg daily are tolerated well.
Symptoms of hypervitaminosis B6 are tingling sensation and numbness in hand or feet, overall poor co ordination and tiredness.
Bottomline – do not just pop in vitamins without consulting a doctor. Take proper advice from a certified medical practitioner for all your health issues.