Q: Does it matter whether I buy milk in plastic jugs or cardboard containers?
A: Absolutely. Because light destroys vitamin A and riboflavin, two key nutrients in milk, the opacity of the milk container is important.
Milk in clear plastic jugs or glass bottles sitting in a lighted dairy case can lose up to 70% of its vitamin A and 20% of its riboflavin after just three days, according to studies conducted at Penn State. Besides this possible nutrient loss, light imparts an "off" flavor. To get the most nutritious and best-tasting product, you should buy your milk in cartons.