Every day our body needs a small amount of vitamins and minerals. A varied diet generally provides enough of each vitamin and mineral. However, some people may need supplements to correct deficiencies of particular vitamins or minerals.
Taking higher than recommended doses of some vitamins may cause problems. For example, the vitamins A, D, E and K are fat soluble, which means they are stored in the body. High doses of these vitamins can be toxic. High doses of some water soluble vitamins, like vitamin B6, can also become toxic. Large intakes of fluoride (especially in childhood) may stain, and even weaken, the teeth. Very large doses of fish oil can lead to decreased blood clotting. High levels of vitamin B6 have been linked to some types of nerve damage. Doses of vitamin C above one gram can cause diarrhoea. High doses of vitamin A may cause birth defects, as well as central nervous system, liver, bone and skin disorders.
Such an example is the excess of a vitamin from B complex, which produces depletion of sources of other vitamins in the same category. In addition, random combination of vitamins can have disastrous effects on the body.
Too much vitamin A, is harmful in pregnancy.
Vitamin A is a powerful antioxidant that stimulates immunity and improves visual acuity. The recommended daily dose, recommended of specialists is between 0.6 and 0.8 mg for adults, the maximum permissible dose being 1.5 mg per day.
In large amounts, vitamin A can become toxic, causing chronic fatigue and sleepiness. In pregnant women, excess intake of vitamin A can cause premature birth or miscarriage.
High doses of vitamin C can form kidney stones.
Although it helps maintain health at the cellular level and rout colds, excess of vitamin C can prevent proper elimination of toxins through the urine, allowing for the formation of kidney stones.
Furthermore, vitamin C excess (more than 300 mg daily) may cause nosebleeds, bleeding and even scurvy, which, untreated in time, can be fatal. The recommended daily dose of vitamin C is 60-95 mg daily and this dose may be taken from a glass of fresh orange juice and a broccoli salad.
Vitamin PP reduces the blood pressure
Vitamin PP assures normal brain function, prevents pellagra (hence the designation "PP"), a disease caused by poor diet, and reduce the blood pressure. But excess of this vitamin may increase the risk of gout and diabetes. The daily intake of vitamin PP is averaging 18 mg per day.
Hypercalcemia decreases the absorption of other minerals
Excessive intake of calcium attracts a malfunction of the kidneys and reduces the absorption of other minerals such as zinc, iron and magnesium. Also, researchers at the University of California, believe that excess of calcium may contribute to the narrowing of blood vessels in the brain and causes neural damage and installation of dementia.
We really need to define what we mean by large quantities. If it means much more than what is required by the body, then definitely too much of any thing is bad. Things such as medicines and food supplements and nutrients in concentrated forms such as vitamins and minerals are particularly bad, whether or not advised by specialist. At the minimum excessive intake of such nutritional supplements is wasteful as it may not be absorbed or used by the body. Another common general problem in regularly taking excessive amount of these nutrients in concentrated forms is that it reduces the ability of body to absorb these nutrients from our normal food. Also studies have shown that nutrients present in natural food items frequently produce better results than the same substances in artificially produced concentrated forms. In addition to these common problem applicable to all type of nutritional supplements, excessive intake of different substances can cause additional different problems specific to each substance.
We need to follow the advice of specialist in this matter because the under specific health condition and medical treatment, it may become necessary to take varying amount of vitamins and minerals. As lay person we do not have enough knowledge and skills to decide by ourselves the dosage under these special conditions.