250mg magnesium 500mg slow niacin with nicotinic acid and potassium gluconate.healthy male 35 yes. take these, or no?

No need: You will get all of these in a healthy balanced diet. There is really no need to spend money on vitamins.

Wallet drain: If healthy and normal diet, no reason to take supplemental potassium or niacin, both of which can have bad side effects. As most people tend to run low on magnesium, and it has a weak muscle relaxer & cathartic effect, you could take the magnesium, but it isn't essential either. Save you cash for good quality food.