For a long time now, my husband has been asking me to help him understand why traditional fats are a very important part of a nutritious diet, and why manufactured fats are not an acceptable substitute. This post is for him.
The so-called evidence against saturated fat, a significant component of traditional fat, begins with a biochemist named Ancel Keys. In the 1950’s Dr. Keys said that the risk of heart attack increased with the amount of saturated fat eaten. In a famous paper on the subject, he confirmed his hypothesis with data from 6 countries: Japan, Italy, Australia, Canada, the United Kingdom, and the U.S. The problem? He evaluated a total of 22 countries, and dropped the ones that did not support his hypothesis. So he excluded the data from the other 16 countries, such as Norway and Holland, with relatively few deaths from heart disease despite a high-fat diet, and Chile, with a high incidence of fatal heart attacks despite a relatively low-fat diet.
In a previous post, I discussed the Framingham Heart Study, the ongoing, 60-year study of what has now become several generations of families in Framingham, Massachusetts. One of its directors famously stated that, “We found that the people who ate the most cholesterol, ate the most saturated fat, ate the most calories, weighed the least and were the most physically active.” We observe that while saturated fat increases total cholesterol, it is due to a rise in HDL, the good cholesterol.
What is a saturated fat anyway? Last week I explained that each carbon atom has a total of four possible binding sites. I used the example of a commuter train to describe how trans fats are structured. To continue on this track, I would say that a saturated fat is like a commuter train with all the seats filled. It is, simply, a chain of carbon molecules in which all the binding sites are filled.
Saturated fats come in different lengths, from short (like 6 carbons) to medium (12 and 14 carbons), to long (like 18 carbons or more). Each one has a different name. The saturated fats are very important biologically, not least because they make up 50% of our cell membranes. Saturated fats help bones to absorb calcium. They protect the liver when it metabolizes toxins like alcohol and acetaminophen. Palmitic acid, the 16-carbon saturated fat, helps lungs transfer oxygen between the air and our blood, and protects against asthma and other lung diseases. Palmitic acid and stearic acid (18 carbons) are preferred nutrients of heart muscle.
Butter and coconut oil are valuable sources of medium-chain lauric acid (12 carbons) and myristic acid (14 carbons), which support our immune systems and help white blood cells to recognize and destroy viruses, bacteria, fungi, and even tumors. Saturated fatty acids are involved in the production of many hormones, including insulin. They signal our brains to feel satisfied after we eat. So it should not surprise you to learn, given all these biological functions, that saturated fats make up 54 percent of the fat in human breast milk. Monounsaturated fats make up most of the rest, at 39 percent. Monounsaturated fats have one open binding site (mono = one). Polyunsaturated fats make up the remainder. Polyunsaturated fats have more than one open binding site (poly = many).
Switching gears now, last week’s post drew a lot of comments and additional information about Crisco. I learned many interesting things, a few of which I will share with you here. It turns out that the name “Crisco” comes from the phrase CRYstallized Cottonseed Oil, from which Crisco was originally made.
The story of Crisco begins with William Procter and James Gamble, who were a candle maker and soap maker, respectively, living in southwest Ohio. Between 1890 and 1905, Procter and Gamble purchased 8 cottonseed mills in Mississippi. Their goal in purchasing the mills was to secure for themselves an alternative source of raw material for their two businesses. The making of soap and candles required large supplies of lard (from pigs) and tallow (from beef), the prices for which were controlled at the time by the meat packing industry.
After they had obtained ready access to large amounts of cottonseed oil, a chemist named E.C. Kayser helped Messrs. Procter and Gamble to develop the process of hydrogenation. Hydrogenation converted liquid cottonseed oil to a solid form that the men could use to produce more soap and candles. At the same time, these two brilliant entrepreneurs realized that the newly invented light bulb was causing the market for candles to shrink. So they began to look for another market for their new product.
Because of its resemblance to lard, P&G decided to market Crisco as a food. They presented it as cleaner, healthier, cheaper and certainly more modern than lard. Then they made advertising history with the publication of a free cookbook, each of whose 615 recipes used the new product. Crisco introduced partially hydrogenated fat to the American diet. The damage would not become apparent for decades.