Whole grains and whole grain products are good sources of all B-complex vitamins except vitamin B-12 and biotin. Legumes, citrus and leafy green vegetables also provide B-complex vitamins. Eggs, meat and dairy products are rich in several B-complex vitamins, including B-12, which has few other natural sources.
Because of the importance of B-complex vitamins, manufacturers routinely add them to many cereals and grain products. Nonetheless, the best way to get enough of these vitamins is to eat a balanced diet with a wide variety of food sources. Harvard's School of Public Health recommends avoiding foods heavily fortified with folate to avoid exceeding the recommended maximum of 1,000 micrograms per day.
Vitamin B-9, or folate, is best known for its role in preventing spinal birth defects. It also plays roles in red blood cell function and in synthesizing the essential amino acid methionine, along with vitamin B-6, or pyridoxine, and B-12, or cobalamin. Vitamin B-6 also helps with the immune system and babies' brain development. The body uses vitamins B-1 (thiamine), B-3 (niacin) and B-5 (pantothenic acid) to help turn carbohydrates from food into glucose, the body's primary energy source. Vitamin B-2, or riboflavin, helps support red blood cell functioning, and vitamin B-7, or biotin, plays a role in synthesizing fats and proteins.