Final answer:
Riboflavin is destroyed by exposure to light, which can also adversely affect vitamin B9 (folate) levels in the body by up to 50% after just one hour of sunlight exposure.
Step-by-step explanation:
The vitamin riboflavin is destroyed by exposure to light. This trait is shared by some other vitamins, such as vitamin B9, which is also sensitive to light. For instance, in people with light skin, as little as one hour of intense sunlight can reduce their body's levels of vitamin B9, also known as folate or folic acid, by up to 50%. This illustrates the importance of protecting certain nutrients from light to preserve their effectiveness.