The term ONE OF THE Bs refers to two essential vitamins, thiamin (also known as vitamin B1) and niacin (also known as vitamin B3). Thiamin is an important nutrient for the body's metabolism and energy production, while niacin helps the body break down carbohydrates, fats, and proteins. Both vitamins are found in a variety of foods, including whole grains, legumes, nuts, and meat. Deficiencies in either vitamin can lead to serious health problems, so it is important to ensure that ONE is getting enough of these essential vitamins in their diet.