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Like many of you, I have some friends who pursue a rigorously vegan diet. Well, actually "friend" may be overstating the closeness of our relationship. We belong to the same church. Every time they talk the subject is why their diet is superior to everyone else's and the problem with meat eaters is they are weak and ignorant. You may know people like that.
Also like many of you, I have friends who are essentially carnivores. They eat meat at every meal, and almost nothing else. In my social setting, people don't claim superiority for being meat eaters. They just eat meat. I find it easier to interact with my meat-eating friends. I am myself an omnivore, that is, I eat all kinds of foods. I limit the amount of meat I eat to the protein I think I need, and I avoid eating foods that I know take a toll on the environment. I haven't always done that, but I do now.
Moral issues aside, many people are absolutely sure that a mostly-meat or an all-plant diet is best for health for every human being on the planet. Recent scientific investigation has found that the truth is that different diets are better for different people, on account of genetics.
Meat Is the Main Source of an Essential Fatty Acid
Dr. Kaixiong Ye, a researcher at Cornell University, has announced the discovery of a gene that gives some people an unusual ability to thrive on a vegetarian diet. This gene, named FADS2, gives some people to synthesize a compound called arachidonic acid.
Arachidonic acid is sometimes portrayed as a toxic substance, but the truth is that it is essential for human life. Although it is a n-6 fatty acid and n-6 fatty acids are associated with the body's production of inflammatory hormones, arachidonic acid is also an important building block in nerves, muscles, and the liver. It forms up to 20 percent of the membranes that line cells in these organs, and it is essential for conducting signals from adjacent cells and the rest of the body to the cell so it can function as part of a tissue. Arachidonic acid is a building block of the hormones that the body needs when it is in "fight or flight" mode, and it's essential for limiting bleeding and for activating the immune system.
Arachidonic acid is a "conditionally essential" fatty acid. Our bodies can make arachidonic acid out of another fatty acid called linoleic acid. This precursor fatty acid is abundant in olive oil and oils pressed from sunflower seeds, hemp seeds, and sesame seeds. It comprises over half the fatty acids in soybean oil, corn oil, and poppyseed oil. If you have ever stepped on a cockroach, the disagreeable smelling oil that oozes out of the roach's body is largely linoleic acid.
The reason arachidonic acid is "conditionally" essential is that even though our bodies can make it, they can't always make enough of it. The only way many people (and some animals, house cats, for example) can get enough arachidonic acid is to eat meat, and lots of it. However, some people don't have to eat meat.