The general public can rest relatively assured that, when there is a broad consensus on some subject, with numerous studies published over the years repeatedly finding similar results, it's a good idea to follow the scientific advice (that typically follows the consensus).

For example, in what regards coconut oil, it's far from just two doctors from Harvard recently saying that coconut oil is bad for you. From the wikipedia page on the vegetable fat:

Due to its high levels of saturated fat, the World Health Organization, the United States Department of Health and Human Services, United States Food and Drug Administration, American Heart Association, American Dietetic Association, British National Health Service, British Nutrition Foundation, and Dietitians of Canada advise that coconut oil consumption should be limited or avoided.

The same goes for various allegedly "controversial" subjects like saturated fat and heart disease, sugar, salt, etc. You can typically find advice by multiple public health organisations and multiple studies reporting findings very similar to each other, stretching back decades. Just because then a new study comes out that bucks the trend, which is immediately widely reported in the popular news as a "groundbreaking new study", or because someone (often, not an expert) writes a book that tells "the truth" about the subject, is no reason to get confused.

In science always follows the consensus, as in business always follow the money.