Vitamin B1, also called thiamine, is a potent antioxidant—which you probably remember as the thing that fights damaging free radicals. Thiamine helps the body use carbohydrates effectively, so it’s essential to metabolism—in fact, it is used to treat problems with metabolism. A serious deficiency in vitamin B1 can even result in dementia! Brain problems associated with vitamin B1 deficiency include confusion, memory loss, and mood changes such as apathy. Some evidence supports the belief that thiamine can help increase energy and improve learning. People who drink a lot of alcohol have a high risk of B1 deficiency. The recommended dietary allowance (RDA) for adults is 1.1 milligrams per day for women and 1.2 milligrams per day for men. Researchers don’t have enough information on adverse effects to set a UL (upper limit). You can find vitamin B1 in yeast, meat, nuts, beans, and in cereal grains like oats and rice.