Vitamins are molecules found in food that are essential for growth, reprodection, and overall health. All vitamins have a toxic level. Often this level is not reached because the vitamins can be flushed out. But some vitamins remain in the system and cannot be removed easily. The Recommended Dietary Allowances (RDA) are guidlines to follow concerning proper nutrient and vitamin consumption.

There are two main categories of vitamins. Fat-soluble vitamins dissolve in oil and water-soluble vitamins dissolve in water. The fat soluble vitamins include vitamin D, vitamin E, vitamin K, vitamin A (retinol). Water-soluble vitamins are folate (folic acid), B12 (biotin), B6 (niacin), thiamin, riboflavin, pantothenic acid, and vitamin C (ascorbic acid).

Some vitamins are used to treat diseases. Folate can be used to reduce the risk of birth defects and possibly protect against cancer. Vitamin C is rumored to help boost the immune system, fight off the common cold, and increase health. Niacin can be used to help reduce heart disease.

Most people do not benefit form taking a vitamin supplement because the majority of vitamins are provided in the diet of healthy people.  Food is the best and safest source of viatmins.

Fat-soluble vitamins are the easiest to overdose with because the vitamins can be stored in the fat of the body and are harder to remove from the body.

Vitamin D- D is the easiest and most common vitamin overdose because the toxic level is not significantly higher than the RDA. The toxic dose depends on the length of consumption. 1 or 2 mg daily taken over an extended period or a 50 mg dose can produce toxic effects in an average adult. The symptoms include nausea, vomiting, pain in the joints. It can also produce constipation and diarrhea and can stimulate a tingling sensation in the mouth. The effects of too much vitamin D are irreversible. Calcium crystals can build up in the soft tissue and harm the lungs, kidneys, and heart. Vitamin D is found in fortified milk and and fish oils. It is responsible for cellular maintenance. RDA--5-10mg/day.

Vitamin A- Retinol is the second most likely vitamin for and overdose. This can occur by consuming 20mg of retinol daily for a prolonged period and can be achieved by eating a large amount of certain foods. 30g of beef liver, 500g of eggs, or 2,500g of mackerel each have about 10g retinol. The side effects of consuming too much retinol are water in the brain, vomiting, tiredness, bone pain, constipation, severe headaches, dry skin, brittle nails, and hair falling out. The problem is more severe in pregnant women because vitamin A toxicity can produce birth defects such as problems with the face, heart, nervous system, and thymus gland. Vitamin A is found in liver, fortified milk, red and yellow vegetables, and orange fruits. It is responsible for vision, immunity, and cell growth. RDA--600-900mg/day, more if pregnant or lactating.

Vitamin E- Too much vitamin E can result in headaches, tiredness, double vision, and diarrhea. There is also some evidence to suggest that megadoses of vitamin E affects the absorption of the other fat-soluble vitamins. Too much E may show as deficiencies of D, A, and K. Vitamin E is found in plant oils, seeds, nuts, and things made from oil. The functions are to serve as an anti-oxidant and prevent free radicals. RDA--11-15mg/day.

Vitamin K- Megadoses of vitamin K over a prolonged period result in anemia. It was discovered that infants and newborns can die from 10mg doses given for three days. Vitamin K helps protect newborns from a disease called hemorrhagic disease of the newborn, but the amount used was fatal. Now a variation of vitamin K is used to protect the newborns. Vitamin K is found in green vegetables and can be produced by the liver. It is used to make blood clotting factors and bone proteins. RDA--90-120mg/day less if pregnant, lactating, or adolescent.

Water-soluble vitamins are far less likely to cause toxicity. Because they dissolve in water, if a person continues to drink water the excess vitamins will more than likely be flushed out. But a few are worth mentioning.

Vitamin C- A daily supplement of 3g of Vitamin C has been shown to increase the risk of kidney and gallbladder stones. Vitamin C can be turned into oxalate in the body. Kidney and gallbladder stones are made from oxalate. A 3g supplement doubles the amount of oxalate that passes in the urine. RDA--60mg for adults.

Folate- Evidence shows that folate is toxic at levels of about 20g of folic acid/day. This can cause kidney damage. Megadoses of folate supplements have been shown to cause pernicious anemia which can result in nerve damages.

Vitamin B₆- Clearly toxic at about 1000x the RDA, this vitamin can cause unsteadiness, difficulty handling small objects, difficulty walking, tingling in the legs and feet, and numbness in the hands when taken at 2-5g per day. However, the negative affects are reversible. Once the megadoses are stopped, symptoms begin to reduce after 2-3 months. Complete recovery may take over two years.

There is such a thing as too many vitamins. Vitamin toxicity is a serious issue with horrible side effects. For most adults taking vitamin supplements is not necessary. The best way to get your viatmins is to eat healthy. If you are going to take a supplement read the ingredients, know the difference between different forms of viatmins, and know the RDAs for the vitamins.

(www.healthline.com)