Before 1910, we had primarily butterfat, beef tallow, and lard in our diets. During Napoleon’s reign in France in the early 1800s, a type of margarine was invented to feed the troops using tallow and buttermilk; it did not gain acceptance in the U.S.
In the early 1900s, soybeans began to be imported into the U.S. as a source of protein; soybean oil was a by-product. What to do with that oil became an issue. At the same time, there was not enough butterfat available for consumers.
The method of hydrogenating fat and turning a liquid fat into a solid one had been discovered, and now the ingredients (soybeans) and the “need” (shortage of butter) were there. Later, the means for storage, the refrigerator, was a factor in trans fat development.
The fat industry found that hydrogenated fats provided some special features to margarines, which unlike butter, allowed margarine to be taken out of the refrigerator and immediately spread on a slice of bread. By some minor changes to the chemical composition of hydrogenated fat, they also found such hydrogenated fat provided superior baking properties compared to lard.
Margarine made from hydrogenated soybean oil began to replace butterfat. In England, hydrogenated fat began to replace lard in the baking of bread, pies, cookies, and cakes in the 1920s.
The structure of a natural unsaturated fat is called a cis fat. The structure of some cis fat, after hydrogenation, changes into a trans fat. This process also happens in milk-producing animals.
For example, grass naturally contains omega-3 and omega-6 fatty acids. When cows eat grass, the enzymes in their stomachs change the cis to a trans fat; their butter thus contains 2-4% trans fat. However, this natural trans fat has a different chemical composition than the trans fat produced by industrial hydrogenation.
It was assumed by the FDA that the hydrogenation of soybean oil produced the same trans fat chemically and worked the same way in our bodies as the natural trans fat in butter. That is not the case. It took 60 years before the chemical composition was shown to be different and nearly another 10 years before its effects on the body were demonstrated to be different as well.
Negative Effects of Manufactured Trans Fats
The National Diet Heart Study, one of the most comprehensive studies on the possible role of dietary fat in heart disease, was carried out in the 1960s. What’s important about this study, in hindsight, is that the key to lowering blood cholesterol levels was to decrease the amount of trans fats in the diet and to increase the amount of linoleic acid, one of the essential fatty acids every human needs to keep blood flowing.
Many researchers concluded that consuming margarine was best, not knowing that the essential feature was the increase of linoleic acid in the margarine. The composition of the margarine was the key.
At a conference in 1979, chemists specializing in fats and oils expressed concern about trans fats in the diet; in essence this was a warning to the industry to examine trans fats, but one they did not heed to any great degree. Consumers kept eating trans fats. This dangerous diet continued.
To demonstrate the effect of consuming trans fats, we looked at the composition of the heart arteries of pigs that were fed different diets. We fed a group of pregnant swine partially hydrogenated fat that contained 43% trans fat. We also fed two other groups of pregnant swine either corn oil or butter fat.
The piglets born to the swine that were fed partially hydrogenated fat contained almost 3% trans fat in their arteries at 8 weeks of age. They contained less arachidonic acid than the piglets born to the other two groups. This indicated their mothers converted less arachidonic acid from linoleic acid.
Arachidonic acid is essential to the synthesis of prostacyclin, that keeps the blood flowing. The milk from the swine fed partially hydrogenated fat contained significant amounts of trans fat, which the piglets received when nursing. Piglets born to swine who were fed corn oil or butterfat in their diets had no changes in their arterial developing cells and contained no trans fat .
There is a parallel between the effects of trans fat on pigs and on humans. For example, if a mother is breast-feeding her child and also eating any kind of food with trans fats, she would have a substantial amount of trans fats in her milk supply and pass those to her infant which cause a decrease of arachidonic acid in their arteries.
In cases where children died and had been autopsied, 99% showed the beginning stages of hardening (calcifications) of the arteries, which ultimately leads to heart disease.
Trans fats that come from hydrogenated fat change the composition of the arteries while natural trans fats do not. Trans fats also reduce the amount of prostacyclin released by endothelial cells that line the arteries.
The conventional preventive approach developed for lowering the risk of heart disease involved monitoring the amount of saturated fat and cholesterol in the diet. Eating little saturated fat and maintaining low cholesterol levels were recommended.
This meant reducing the consumption of meat and meat products, dairy foods, and especially eggs, all of which contain cholesterol. It also meant replacing saturated animal fat, such as butter, with saturated fat made from vegetable oil produced by hydrogenation, such as margarine.
This dietary approach was generally familiar to most people both through the medical advice they were given, and through television and magazine advertisements for margarines, vegetable oils, and shortenings and a number of vegetable protein meat- and egg-substitutes.
Even today, the words “no cholesterol” on the label of a food item helps sell it, even if that food in any form never contained cholesterol in the first place. Much of the research on heart disease has concentrated on diet as the culprit in heart disease, particularly high dietary cholesterol levels; this is the traditional or cholesterol hypothesis. As a consequence, many people try to alter their diets and take drugs to lower the cholesterol levels in their blood. Yet, this has not worked to prevent heart disease.
To summarize, the consumption of hydrogenated fats, which are in foods like margarine, and partially hydrogenated soybean oil, can throw off the balance between prostacyclin (needed for blood flow) and thromboxane (needed for clotting) production in the body. Up to this point, the assumption was that adding enough linoleic acid would compensate for what trans fats might be doing to the production of prostacyclin. However, that is not enough to overcome the negative effects of trans fats.
On November 7, 2013, the U.S. Food and Drug Administration (FDA) announced that it would ban all manufactured trans fats. Finally my goal had been reached, one that began with my first publication on trans fat in 1957.
Fred A. Kummerow, Ph.D.
This excerpt is from “Cholesterol is Not the Culprit. A Guide to Preventing Heart Disease” by Fred A. Kummerow, Ph.D. with Jean M. Kummerow, Ph.D. The book is fully referenced.
Photo of Dr Kummerow: L. Brian Stauffer