Metric system. Metric system, international decimal system of weights and measures, based on the metre for length and the kilogram for mass, that was adopted in France in 1795 and is now used officially in almost all countries.
However, if taken in large doses, vitamin D side effects may include: Thirst; Metallic taste in the mouth; Increased urination; Decreased appetite; Weight loss; Constipation; Vomiting; Diarrhea; Itchy skin; Loss of muscle tone; Irritability; Tiredness; Sore eyes; Pain in the bones and joints ...
1 Vitamin B12, which helps folate make cells, works differently than any other vitamin. Learn the details at How Vitamin B12 Works.  Vitamin A plays an essential role in eyesight. Learn how it helps us to see, even in the dark, at How Vitamin A Works.