It’s probably not necessary to take B complex every day if you eat a healthy diet and have no medical conditions that make it difficult to absorb the vitamins from your food., The B Vitamins present in a B-Complex supplement are important for older adults to take daily. For example, men and women 51 and older are recommended to get more Vitamin B1 (Thiamin), Vitamin B2 (Riboflavin), Vitamin B3 (Niacin), Vitamin B6 (Pyridoxine), and Vitamin B12 (Cobalamin)., The recommended daily allowance (RDA) of vitamin B1 (thiamin) is 1.5 mg per day for an adult, and 0.7 mg for children age 1 to 4. Thiamine is generally nontoxic. The RDA for vitamin B2, Biotin is safe to take — even at high doses. But biotin supplements can affect the results of certain blood tests. Talk to your primary care provider (PCP) if you think you’ve taken too much biotin. You can also contact Poison Control if you’re having trouble reaching your PCP., For instance, adults typically need around 1.2 mg of thiamine, 1.3 mg of riboflavin, and 2.4 micrograms of B12 daily. However, it’s essential to consult with a healthcare professional to determine the specific needs tailored to your individual health profile., Adult women need 1.1 milligrams of vitamin B1 each day, and adult men should have 1.2 milligrams. Vitamin B1 is a water-soluble vitamin, which means that if you take in more than you need, you'll excrete the excess in your urine..