Petitions in parliament (paper ones) are proceedings in parliament which means they are covered by article IX of the 1688 Bill of Rights (similar in function to the US bill of rights).
The petition has a rather odd wording because the rules as to what is allowed are a little bit complicated, but it comes down to the details of problems with the regulatory process that prevent people being told things which are factually true and evidence based about substances with a known safety record.
“When I was living in Germany during the 80s and 90s, I could not buy common food supplements that I could buy in the US. I was told that in Germany a food supplement must prove its safety; it also had to prove efficacy. Is this correct?”
In the 1980s–90s, your impression in Germany was mostly correct: many products that were simple “supplements” in the U.S. were treated as medicines there, so they had to show both safety and efficacy to be sold, especially if they were in pill form or made health claims. Products that counted as foods still had to be safe, but not proven effective in the same way.
By contrast, after the U.S. passed DSHEA in 1994, most supplements were legally treated as foods and could be sold without pre-market proof of safety or effectiveness, as long as they stuck to vague “supports health” claims.
Germany’s Commission E evaluated herbal medicines using a broader range of evidence than modern drug trials: published and unpublished studies, pharmacological data, long traditional use, expert opinions, and case histories. This allowed many long-used herbal products to stay on the market, even when rigorous randomized trials were limited.
The problem with the system in the UK and the EU is that there are high regulatory costs for proving these things at the standard required by the system, but no IP available for anyone who funds those costs. Hence no-one will do it.
What they need is to enable people to have provisional claims and build a dataset working with vendors rather than expect a gold plated system.
Safety, of course, is very important, but that is not the issue.