Having just ordered my fourth bottle of Ester-C 500 mg. w/Citrus Bioflavonoids capsules, I thought it was time to add my opinion as a non-medical professional. We all know that the human body cannot manufacture its own Vitamin C. Generally speaking, our bodies need a new supply of C every day, either from food sources or from a product supplement. What is NOT as universally known is that most people cannot absorb more than 500 milligrams of C in a single dose. With that in mind, to obtain my normal supply of 1,000 milligrams of C per day, I'll take one 500 mg. capsule in the morning and another one in the evening. You can buy this same brand in strengths of 1000 mg./capsule, but I prefer to take it in the divided dose I just described. Additionally, along with my morning Ester-C, I take the following individual vitamin supplements: Jarrow B-Right (B-complex), 10,000 IU Beta Carotene (Vitamin A), and a 100 mg. capsule of d-alpha tocopherol (Vitamin E) for optimum functioning under the heavy stress-load I face almost every day of the week. (Don't we ALL?!) My "stress-busting" formula is a compilation based upon writings by Dr. Weil, Dr. Oz, and from reputable health blogs. Only you can determine what's best for your body. My experience tells me this is working: I haven't contracted the flu, a viral infection, or even the common cold in nearly 3 and 1/2 years! In my opinion, American Health is a trusted brand, this product is reasonably priced, and Amazon's delivery service is unmatched