According to some recent research,
Vitamin supplements almost never have health benefits, are a waste of money and could even be harmful, a group of scientists said in a damning indictment of the industry.
This is a complex issue. What the public health authorities are saying is correct. Vitamin supplements have health benefits for certain groups of people in certain instances and there are many studies to show this. Vitamin D and Calcium are often recommended for people at risk of osteoporosis. Some people may have digestive disorders for example that also benefit from vitamins. But as shown in the studies in your link, multivitamins taken by most people are not helpful, and some supplements can even be harmful. High levels of folic acid will cause increased risk of cancer and taking vitamin E may be harmful as well, especially if it is combined with smoking, aspirin or blood thinners. Iron overload is the most common genetic disorder among whites and often goes undiagnosed for many years causing destruction of the liver. Taking extra iron when you don't have an iron deficiency may be harmful for many people.
Many people take supplements that are not strictly vitamins, as well. Many haven't been tested using large clinical tests, so its hard to know if they work or may be dangerous. Usually when they are tested, they are shown not to work. That is why the doctors are saying they are a waste of money. Some do work, though. Probiotics for example reduce the risk of death for intensive care patients. This study says they can be used to reduce death from C Dif, a very terrible infection contracted in hospitals.
So, personally if I want to know if a vitamin, supplement or herb has been tested, is safe, effective and has drug interactions, these are a few sites I like. (This is of course not medical advice. Please talk to your doctor about the supplements you are taking.)