For now, I’ll focus on the split between plants, animals, and fungi, which happened 1.5 billion years ago. At that time, we looked like a blob, a single-celled blob to be more exact. We were nothing like the animals, plants, or fungi that appear today. Since that fateful day billions of years ago, these three main lineages of life have been humming along doing their own things in very different ways. Each kingdom has evolved its own ways of getting nutrients from the environment and transforming them into the energy needed to power their internal “engines.”

We might think of these families of life as three different “operating systems,” like Mac, Android, and Linux. Because I’m partial to Macs, I think of humans as these, with plants as Android, and fungi as Linux. Each operating system has been programmed in a different code and has different internal processes that allow it to run smoothly. If you try to take a program from Android and run it on your iPhone or your MacBook, it’s not going to work, and it might even cause other programs to crash. You’re going to need special software to convert the program to an operable format, and in reality it’s best to just run Mac programs on a Mac because they were specifically designed for that operating system.

You might also think of the three different kingdoms of life as three different types of cars, let’s say Tesla, Ferrari, and Porsche. You’re not going to be able to use Tesla parts in your Ferrari or your Porsche. If you want your car to perform the way it’s supposed to, it’s wisest to use parts that were specifically designed for it.

Plant molecules like phytoalexins, polyphenols, oxalates, and lectins are like computer programs from a different operating system than ours. They are Android and we are Mac; the programs are not very compatible. When we try to use plant programs in our human operating system, they generally just mess things up, sometimes causing massive problems akin to the “blue screen of death” on your computer. Plants have evolved these molecules for their own personal biochemistry and metabolism, not for ours!

Those Porsche parts don’t work in your Tesla. Contrary to popular belief, plant molecules do not play a role in human biochemistry or metabolism. As you’ll see in future chapters, so called “antioxidants” from plants don’t directly serve an antioxidant role in your body. In fact, they are often doing the opposite—acting as “pro-oxidants.” Our body has its own intrinsic antioxidants, like glutathione, that are part of our programming and that manage the balance of oxidation and reduction just fine on their own. In fact, multiple studies have shown that supplementation with plant “antioxidant” molecules do nothing to improve antioxidant status in humans and are often associated with worse outcomes.5,6,7-10

When we eat animal foods, we are eating foods from the same operating system as humans. The biochemistry and metabolism of animals look a whole lot more like ours than those of plants or fungi. Plants use photosynthesis to generate energy as they inhale carbon dioxide and expire oxygen. Animals do the opposite, breathing in oxygen and producing carbon dioxide as a by-product of cellular respiration. Similarly, the plant-based forms of many vitamins and nutrients look very differently from the corresponding animal-based forms. Beta-carotene vs. retinol (vitamin A), alpha-linolenic acid (ALA) vs. DHA (omega-3 fatty acids), and vitamins K1 vs. K2 are all examples of this and will be discussed in much greater detail in Chapter Eight. In that chapter, we’ll also discuss the many nutrients key to optimal human function that don’t occur in appreciable amounts in plants or fungi, like vitamin B12, choline, taurine, carnitine, carnosine, vitamin K2, and others.