Mr Lovell suggested that supplements can be beneficial, although he said that they should be used to complement a healthy diet.
He said: "The biggest mistake [people make] is they don't look at their diet first and they try a supplement as a magic product when they don't deal with the bread and butter stuff first."
Consumers should aim to build a "foundation" of healthy food before they think about taking supplements, he said.
Mr Lovell also explained that people should avoid eating or drinking too much of any one particular type of food or beverage.
He gave the example of caffeine, which he said could "be poisonous" if drank in excess.
Researchers from the National Institutes of Health recently suggested that contrary to previous fear, taking folic acid supplements do not worsen issues for those with health problems related to low vitamin B12 levels.