This is, of course, a major philosophical debate. I will just say that there could be reasons this is the government's business.

One issue with modern food production for consumers is that it can be difficult to determine whether a particular ingredient is safe or healthy. Information has public good qualities, and having each consumer make an individual determination about whether each ingredient is safe/healthy is costly. The obvious way to justify government intervention here is that it's more efficient for us to pool resources and empower a third-party to produce the information we need and ban/label products that are likely unsafe. The decisions won't always be right, but the approach might be much preferred to the alternatives.

Plus, conditional on socializing a lot of medical costs, it might make sense to put restrictions on behaviors that affect individual health.