Some experts say that a fact is common knowledge if it can be found in three independent sources. Purdueâs Online Writing Lab recommends finding five independent sources before considering a fact common knowledge. The point is that common knowledge can be found in a variety of sources.
VITAMIN D. Vitamin D and vitamin A are the most toxic of the fat-soluble vitamins. The symptoms of vitamin D toxicity are nausea, vomiting, pain in the joints, and loss of appetite. The patient may experience constipation alternating with diarrhea, or have tingling sensations in the mouth.
With some vitamins and minerals, the upper limit is pretty close to the RDA. So it's easy to get too much. For example, a man who takes just over three times the RDA of vitamin A would get more than the upper limit. High doses of vitamin A -- and other fat-soluble vitamins like E and K -- can build up in the body and become toxic. Other risky supplements include the minerals iron and selenium. Supplements are designed to be additions to your diet.