Supplements are explicitly not considered "health care" in the US
Countries with single payer also offer eye drops, family doctor visits, and LASIK... they just tend to pay less for them
You don't need "government force" to change how health insurance works. See Germany, many other countries. All you do is create a government healthcare pool that's large enough to cover risk, fund it, and give folks the option of using it or using a private insurer that will cost a lot more.