I think there can be some simple regulation. IE take this public office and you must remain impartial for the rest of your career. It should be a privilege to serve.
Take a look at Aspartame controversies. In essence the US Attorney charged with opening a grand jury into their research withdrew and took a job working for Searle, manufacturers of Aspartame. The Grand Jury never occurred. A few years later the FDA Commissioner who gave Aspartame the green light went on to work for their PR company. To this day people don't trust Aspartame even though (debatably) the research shows it's safe.
So even perceived conflicts of interest can adversely affect public perspectives on the objectivity of scientific research. That's not good in a democracy.
