Vitamin D is one of the most accessible vitamins for anyone to take. All you need to do is expose your skin to the sun for around 10 to 15 minutes. Vitamin D is also readily accessible in many kinds of food, including fish, fruits, vegetables, legumes, bread, and meat. Vitamin D has been shown to beneficial for those with Alzheimer’s disease and has a protective effect on some forms of cancer. Overdoses of this essential vitamin however, can be quite dangerous, with internal organ damage, vomiting, nausea, weakness and weight loss being distinct possibilities.