I have to admit that it was fairly well-known that Beets contain a fair amount of nitrates which are then converted by the body to nitric oxide, NO. In this form it is generally regarded as good for the BP, although its effects will be self-limiting, i.e. too much has no effect. The powder form is also available for those who don’t like the taste. I also thought that the chief role of the active ingredient of cayenne, capsaicin, is to reduce inflammation and pain, rather than reduce the BP, although it does some of the latter too.
I do not know much and it is clearly not a mathematical proof, for different physiologies ‘may’ have different effects. For example, a standard antihypertensive is meant not to be taken with grapefruit, for one ‘may’ get hypotensive as a result, and this lays one open to fainting or worse. But they don’t say that grapefruit only affects 10% of those taking antihypertensives - so says my pharmacist - and hence the general prohibition acts as a safety net. Therefore I experimented and checked my BP frequently for some while. No effect. So I eat grapefruit a lot, for it is my favourite citrus fruit and I am still taking antihypertensives at the same time.
So it could very well be that ‘may’ is just being safe?
This is an interesting and useful topic. I look forward to more learned responses, for I currently have only part of the picture.