Google “vitamins” and you’ll get 142 million results. That’s more than what you get for “Brad Pitt,” but the descriptions are just as breathless. As you navigate the maze of sites, you’ll see phrases claiming that vitamin supplements can “increase energy,” “stimulate brain function,” and “improve sex drive.” It all helps explain why Americans shell out $7.5 billion a year on vitamins, hoping to prolong life, slow aging, and protect against a bevy of illnesses.
But new research not only refutes many of these claims, it also shows that some of these vitamins may, in fact, be harmful in excess. Vitamins got their name from their link to “vitality,” and indeed they are vital for your health. But it’s important to get them from the right place and in the right amounts. Similarly, while minerals such as calcium, iron, and zinc are essential to keep your body and brain functioning properly, many are highly toxic if consumed in large quantities.
To date, 13 vitamins essential to human health have been discovered. Vitamins are classified as fat soluble or water soluble, according to how they are absorbed and stored in the body. The fat-soluble vitamins (vitamins A, D, E, and K) need fat in order to be absorbed into the bloodstream from the intestinal tract. Thus, people who have fat-malabsorption disorders can develop deficiency symptoms even if their diet supplies adequate amounts of a vitamin.
Many people with celiac disease, for instance, which impairs the absorption of dietary fat, have low vitamin D levels. On the other hand, because the body can store fat-soluble vitamins in the liver and fatty tissue, toxic amounts may build up if a person takes high doses of these supplements. As water-soluble vitamins, the B vitamins and vitamin C are more easily absorbed than fat-soluble vitamins.
However, since the body stores water-soluble vitamins in only small amounts and excretes the rest in urine, they need to be consumed more often. (This also means that you’re not likely to overdose on water-soluble vitamins.)