Meta exempts general food from its health-ad age rules, but if you sell keto or low-sugar bakes as weight-loss products, those ads must target people 18 and over, and no ad may claim a product cures a condition such as diabetes.
Meta's personal-attributes rule rejects copy that implies you know a viewer's health; "Do you have diabetes?" is Meta's own example of a non-compliant ad. Write "No added sugar, sweetened with dates" rather than "Diabetic? Treat yourself."
In the US, "gluten-free" on packaged food means under 20 ppm of gluten (FDA), which shared flour makes hard to guarantee. In the UK, food prepacked for direct sale, such as boxed brownies or wrapped sandwiches, needs its name, full ingredients and emphasized allergens on the label (Natasha's Law).