Nor can one talk about a 'natural' human diet.
They get into the human diet via fish, meat and dairy products.
The soybean has been a part of the human diet for almost 5,000 years.
All of this is of more than academic interest for what it might say about the human diet.
Fish are the most common source of mercury in the human diet.
Carbohydrates are a key part of the human diet, but some raise blood sugar more than others.
They tend to have slightly less carbon-13 than other plants that are more abundant in the human diet.
Meat is part of the human diet in most cultures.
The principal source in the human diet is olive oil.
Endosperm thus has an important role within the human diet, worldwide.