Kind of schemantics.. In that world when it is used only as a supplement. I wouldn't call kratom a natural food either, but it is also a plant. Let's just say I make a distinction between natural plants and naturally eaten food. You know, some people do it rocks too.
We are unable to digest or extract nutrients from hard rocks, we are very much designed to eat all sorts of roots and they go through digestion quite well. Your distinction is your own and not based on science or even reality. PS. It's "semantics".
The Natural Testosterone Plan by Buhner is an excellent primer on the subject. It describes the onslaught of testosterone depleting factors in the modern life that have a correlation with men experiencing a slow decline of available testosterone. Factors such as increased soy in the diet, the presence of pharmaceutical agents in our water supply and the rise of plastics are outlined in the book. Weightlifting is documented to boost natural testosterone. After reading the book, one understands that a simple pill is not gonna solve the perceived problem. Supplements like Tongkat Ali, Cordyceps, Ginkgo Biloba, Ginseng can make a difference. For those in northern climates with not many sunny days, simple Vitamin D can go a long way. The one thing I was left with is that lifestyle choices in diet and exercise are the first items to address before going down the attempted quick fix of popping supplements.
Make sure your T levels are low before you take any processed hormones and low T is only one factor in sexual dysfunction. If you are having problems, see a urologist.
Don't worry, aging takes care of high level of T. According to this after 30 we lose 1% per year, so a 50 year old's T level is 20% lower than 20 years earlier. https://www.healthline.com/health/low-testosterone/testosterone-levels-by-age#adolescence Apparently the "normal" T level distribution is pretty wide, 270-1070 for adults.
But if it is such a wide range, for me 400 can be normal and for you maybe 800. So what is normal? I guess the only thing could be to compare to the person's previous reading. But what if the previous was just too high for whatever reason and the current one is the normal? "In general, the normal range in males is about 270 to 1070 ng/dL with an average level of 679 ng/dL. A normal male testosterone level peaks at about age 20, and then it slowly declines." https://www.medicinenet.com/high_and_low_testosterone_levels_in_men/views.htm So let's say if my level is 500, that is below average but still in the normal range. Now let's say if yours was measured 3 times in the past and was always above 700 and now it is at 600, maybe that is a concern... "Moreover, some researchers suggest that the healthiest men have testosterone levels between 400 - 600 ng/dL."
TRT (Testosterone Replacement Therapy) is something you should consider (i.e. look at side effects as well as benefits) if you have low testosterone and you are maybe in your fifties or beyond. I have a couple of decades to go, but I would certainly consider it then (if i had low testosterone levels). I don't think i know any proven 'natural' testosterone boosters.