The human is a biochemical factory. An input (food and drink) into the human factory affects it, however subtle. Each system of the human body, such as the neurological system, requires a certain amount and quality of input in order to be maintained or to grow, and will respond accordingly should the input fall short of, meet, or exceed its input requirements. It is quite possible that when there is noticeable cognitive improvement after consumption, it is because the input had eliminated a significant nutritional deficit for some or other chemical in the neurological system. Studies have reported that vitamin supplements can improve children's intelligence. In Europe and the US, Down's Syndrome children's intellectual development is allegedly boosted by giving them huge doses of vitamins and dietary supplements.
Counter Claim:
There is insufficient or no evidence to suggest that, for people with normal health, any food acts as a cognitive enhancer. Vitamin supplements, so called smart drugs and smart nutrients, and related studies that claim they boost intelligence are all unfounded for lack of sufficient evidence. Studies have simply proved inconclusive. It should be noted that, children who have a poor diet often also lack intellectually stimulating environments (intelligence and environmental conditions). Intelligence is like a muscle, you can use it or lose it, but there is no anabolic steroid equivalent in the IQ community. What really happens is a kind of placebo effect: you really believe you will become more intelligent, and your belief will inspire you. What is clear, is that a lot of money is being made out of the claim.