Simple google search:
Saliva, a thick, colourless, opalescent fluid that is constantly present in the mouth of humans and other vertebrates. It is composed of water, mucus, proteins, mineral salts, and amylase. As saliva circulates in the mouth cavity it picks up food debris, bacterial cells, and white blood cells.
The human mouth can be a den of all types of things, including acid.
Semen also contains more than 50 different compounds including hormones, endorphins, neurotransmitters and immunosuppressants. Other substances present in the semen include the following:
blood group antigens
So if you are a male you might want to take "male vitamins" to help maintain your levels (especially B vitamins) since you're losing some during your normal production of semen.
But this is not "human flesh". The ingredient that can be most tied to "flesh" is protein and amino acids but you can get protein from beans.
Beans are the SEED of the family Fabaceae. So you can get protein from the REPRODUCTIVE cycle of plants, but if the same substance (on which biological life itself is built on) comes from a human you call it cannibalism? Do you call it cannibalism or vampirism when a mother passes her own fluids to her child in the womb?
Do you want to talk about the contents in milk??
A lot of what humans consume contains things that are good and bad. OUR BODIES WERE MADE FOR THIS. If you only took in ingredients your body could use your piss would be crystal clear and you wouldn't even need a butt hole. So we can all play the whole "my body is a temple thing" but temples also have bathrooms where people pass gas and excrete liquid and solid waste. To deny this is to deny human nature itself. Even the air you breathe.
So unless you want to go live in a bubble it is absolutely impossible to avoid germs and toxins. And if you don't consume you don't build up an immunity which means your constitution is actually weaker than those who you think are so wrong and/or unhealthy.