Your favorite health food store has plenty of supplements. But trying to figure out which nutrient is the best—decoding them—can be tricky. Here is a codebook for three widely used and important supplemental ingredients. Vitamin: B6 What it is: Vitamin B6 is available in a variety of forms from food, including pyridoxine, pyridoxal 5’-phosphate, and pyridoxamine. Where it comes from: …