Some studies of the beneficial effect of certain diets and treatments on heart health have been seriously criticized because they also included a large reduction in sugar, which some researchers have long suspected to be a major factor in heart disease.

Fortunately for the sugar industry, as well as other food industries, plenty of scientists are available at attractive prices.

The problem here is that scientists don't directly bring in any money, so the scientist's income is totally dependent on grants. Even if the grants are laundered, a scientist can easily figure out where it's coming from, and what answers are desired. Providing desired answers brings future grant money.

No study, or criticism of a study, can be considered valid until you know the ultimate source of the money.