Are you among those people who take vitamin supplements just because you are worried that you are not getting enough? Well, too much of anything is bad, and that applies to vitamins as well. For most people, a healthy and well-balanced diet should be able to provide all the vitamins your body needs. So, while it may not be easy to overdose on multivitamins through your diet, you could affect their balance in your body if you take more than the required dosage of supplements over a period of time.
Hypervitaminosis is when your body has an abnormally high level of vitamins, which could lead to toxic conditions. Though you could reverse the effects by stopping the dosage or reducing it, an overdose could also affect your health adversely.
While vitamins C and B (Thiamine, Riboflavin, Niacin, Pantothenic acid, Folic acid, Biotin and vitamin B12) are water soluble, where the excess, in most cases, gets excreted from the body, fat soluble Vitamins (K, D, A and E) can get stored in the body and accumulate over time to toxic levels.
So how much is an overdose? Read on to find out the daily limits for fat-soluble vitamins and the dangers of overdosing.
Vitamin D: Also known as the sunshine vitamin, the D vitamin is essential to keep your bones healthy, to maintain a healthy immune system and to ensure your body works the way it should. Vitamin D is created when the body is exposed to sunlight. You can also get vitamin D through certain food such as fatty fish, egg yolk, fortified juices, dairy products and cereals.
However, in cases where the exposure to sunlight is less or when you do not receive enough through your food, you may need to take supplements. The average recommended dosage varies, with the Mayo College recommending 600 International Units (IU), and the Institute of Medicine recommending 4000 IU per day as the upper limit.
Called Hypervitaminosis D, an overdose of vitamin D is a rare, though often serious, condition that can affect the bones, tissues and other organs. Further, since an excess of vitamin D causes calcium levels in the blood to rise, it can also lead to a condition called hypercalcemia, or excess of calcium in the body.
Symptoms of vitamin D toxicity include fatigue, dehydration, irritability, tingling in the ear, nausea, stomach pain, vomiting, dizziness, disorientation and high blood pressure. If left untreated, excessive vitamin D also can cause kidney stone, excessive bone loss or even kidney failure and hardening of arteries.
Vitamin A: This fat-soluble vitamin is essential for normal vision, healthy reproduction, and to ensure that the vital organs such as the heart, lungs and kidneys function well. It also contains antioxidant properties.
Vitamin A is of two types –preformed vitamin A which is found in poultry, meat, fish and dairy products and provitamin A, which is found in plant-based products, fruits and vegetables.
According to experts, the recommended daily allowance for those aged 14 and above is 700-900 micrograms and for nursing women between 1,200 and 1,300 micrograms. However, an upper limit should be maintained at 3000 micrograms to prevent toxicity.
Toxicity could be either acute, where a single, excessively high dosage of vitamin A is consumed, or chronic where doses of more than 10 times the RDA are taken over a period of three years. Side effects include joint and bone pain, dry, rough skin, poor appetite, dizziness. It could also lead to more dangerous situations such as birth defects if consumed by pregnant women and liver damage, if consumed for a longer period of time.
Vitamin E: Found in cereals, meat, poultry, eggs, almonds, leafy vegetables like spinach, vegetable oils and wheat germ oil, vitamin E is known for its antioxidant and anti-inflammatory properties, enhancing the immune system and for preventing clogs from being formed in the heart arteries. While it is found in several forms, only one - alpha-tocopherol – is used by the human body. The daily recommended amount of vitamin E for males is 22 IU, while for lactating women it is 28 IU daily.
While natural, dietary forms of vitamin E are beneficial for health, not much benefit can be gained from supplements. Also, while cases of toxicity are rare, an upper limit of 1465 IU daily is set for adults aged 19 and older. This is because excessive intake of Vitamin E could trigger bleeding.
Vitamin K: The fat-soluble vitamin plays a vital role in producing prothrombin, a protein which is important in blood clotting and bone metabolism. Hence, a deficiency in vitamin K could delay clotting, leading to excessive bleeding. It is also important for keeping the blood pressure low by preventing mineralisation, which is a major risk for heart disease, and for ensuring bone health. Vitamin K is found in vegetables such as cauliflower, broccoli, green leafy vegetables such as spinach and kale, meat, eggs, fish and some cereals. We also get 10 percent of the vitamin from our gut.
There has been no established upper intake limit, when it comes to high level natural forms of vitamin K. However, vitamin K toxicity has been found in formula fed infants who are exposed to high levels of the vitamin, where the effect could include jaundice in new born babies.