I'll give you pointers because I'm not from the same jurisdiction you live in and do not deal with the same laws as you do:
>>How do we break this cycle?
Look for subsidies that make the production of certain crops artificially cheap. You'll find answers as to why the demand for healthy food isn't being met and producion is diverted towards less healthy alternatives.
This gets reflected in the prices of the end product and the sales of it. Which then reflects on the balance sheet of the companies that produce these end products.
Also look at the make-up of the basket of goods in the CPI index and see if there's correlation with which crops are being subsidized. The political incentives are right there.
>>How do we develop a for-profit company that evaluates the food industry independently and informs the people of what is healthy and what isn't?
1. Build a platform online that evaluates food products. Or a customer base offline through word-of-mouth.
2. Gain the trust of people who listen by being consistent and honest.
3. Get into sponsorship agreements with companies that are producing healthy food.
4. Let audience book one-on-one consulting sessions in which diet patterns are recommended.
This business model already exists and there are those I know who are consulting with people and upgrading their diets.
The other option is to invest capital and start producing food that's healthy and of better quality than existing, less healthy alternatives. Looking for regulatory restrictions or barriers that hinder such production will have to be removed.
>>Who quality-checks the quality-checkers?
The service being provided is informational and educational.
When a quality-checker is found to be unreliable, his customers will stop paying for his service. He will lose his position in the market and be replaced by a competing quality-checker.
If it's a legal service that's expected where the food producer is sued in court, then there's the question of whether fraud is involved. If there is, and it isn't punished, then it's a failure of the legal system, not the market.
If the legal system has failed, then private arbitration tribunals that go after the producers for fraud will have to be permitted to exist. And there will have to be a private appeals court system for challenging the decisions from these tribunals.
And I repeat what I said earlier: even with all this, if a person still voluntarily buys something he knows to be unhealthy, then that is his responsibility and noone else's.