Steak - Mark Schatzker [100]
Cardiologists advise their patients to watch how much steak they eat because beef contains three saturated fats: myristic acid, palmitic acid, and stearic acid. Myristic and palmitic acid raise LDL cholesterol. Stearic acid, despite being saturated with hydrogen, does not, and the reason is that humans, just like black Wagyu cattle, produce the enzyme delta-9-desaturase, which grabs hold of stearic acid molecules and removes a pair of hydrogen atoms, converting it into oleic acid, which is monounsaturated and also happens to be found in abundance in canola and olive oils. Thanks to delta-9-desaturase, stearic acid is, from a cardiovascular health point of view, neutral. In grass-fed beef the ratio of saturated-to-unsaturated fat is lower than in corn-fed beef, but not by much. Grass-fed beef, however, does have more stearic acid and less myristic and palmitic acid. It is, therefore, better for you.
The subject of fat, beef, and human health does not end with saturated fatty acids, however. Within the world of unsaturated fats, a storm has been raging for some time now over two important kinds: omega-3 and omega-6 fatty acids. Both are considered essential—like the eight essential amino acids, the human body cannot live without them. Omega-3 fatty acids are believed to fight cancer, prevent heart attacks, soothe arthritis, and promote brain health (among other benefits). Omega-6 fatty acids are associated with healthy skin, vision, and immune system. Eating too much of one, however, makes it difficult for the body to process the other.
For this reason, nutritionists believe the human diet should contain a ratio of omega-6 to omega-3 fatty acids of about 4 to 1. Most North Americans, however, don’t eat nearly enough omega-3 fatty acids, and their ratio is more in the area of 15 to 1, if not higher. The reason for this imbalance is grain, which contains a lot of omega-6 fatty acids, and not much omega-3. (This is one of the reasons that Ted Slanker, the grass-fed beef evangelist on Texas’s Red River, believes grain to be “the atomic bomb of the American food system.”) Although humans have been eating grain for ten millennia, in the last hundred years or so we have become very good at growing it and processing it into all sorts of edible products. We eat cornflakes for breakfast. We pour grain oil on our salads, or emulsify it into mayonnaise and spread it on sandwiches and hamburgers. Corn oil, which we use to fry potato chips and French fries and moisten our cakes and turn into margarine, contains an omega-6 to omega-3 ratio of 46 to 1.
We also feed corn to cows. In corn-fed beef, the omega-6 to omega-3 ratio can be as high as 20 to 1. The ratio in grass-fed beef is usually around 3 to 1 and is sometimes as low as 1 to 1, and the reason is that there are more omega-3 fatty acids in a field of grass than in a concrete trough full of corn.
A person in need of omega-3 fatty acids will get more of them from a plate of walnuts or flaxseeds or wild salmon than from a grass-fed Argentine steak. But walnuts and flaxseeds—and any other nut, leaf, fruit, or seed—have nothing on a steak when it comes to another recently famous fatty acid: CLA, which stands for conjugated linoleic acid, and which, in laboratory experiments, has been found to inhibit the growth of tumors. Grain-fed steak contains CLA, but grass-fed steak contains about twice as much. (The richest known source of CLA is kangaroo meat.)
Grass-fed beef is therefore healthier. In theory, at least. The problem is that it is easier to theorize about human health than it is to predict. It is easier to take a sample of ground beef, separate it into fat and water, vaporize it, and then analyze all the compounds using gas chromatography than it is to predict the effect that all those compounds—not to mention all the other compounds people eat—will have on the human