I was doing research on the web, and i found that iq can be raised or lowered through study and or dietary supplements. is this true?

Not true: Training and practice may help raise score on intelligence tests, but only a very little bit. But they cannot actually change IQ. Dietary supplements for sure do not. Such claims are quackery and should be ignored. Limit online research to legitimate scientific websites etc. Avoid non-professional sites and all resources with products to sell, like test training or dietary supplements.