Is it possible to have too much of a good thing? Yes, apparently. Even something as seemingly innocuous as a multivitamin pill to supplement your diet or “boost” your immune system. Many of us turn to multivitamins, effervescent vitamin C tablets, and over-the-counter supplements when the weather gets colder, thinking it will do our health a load of good. But we could be barking up the wrong tree, says registered dietitian-nutritionist Gabriella Nowicki. Not only do we run the risk of “vitamin overdose,” but the supplement industry is a “huge marketing ploy,” she says. Eat food, not pills. Her…