While there was good reason to move away from trans fats, the expansion of palm tree plantations has come at an environmental cost.
It was a welcome change for the welfare of coronary arteries. It was not so good for the welfare of orangutans. That change was the substitution of palm oil for trans fats in numerous consumer products.
Back in the 1960s, researchers began to associate the consumption of saturated fats, as found in butter, shortening and meat, with deposits in the coronary arteries. Such deposits were in turn associated with heart disease. Industry reacted by looking at vegetable oils, low in saturated fats, as possible replacements for butter and shortening. The problem was that most vegetable oils are liquids. However, there was an apparent solution. If the unsaturated fats in a vegetable oil were subjected to treatment with hydrogen gas, the carbon-carbon double bonds that characterize such oils would take up the hydrogen and be converted to single bonds as found in saturated fats. There would be no point in eliminating all the double bonds, since that would result in a fully saturated fat, just like butter. But “partial hydrogenation” resulted in a product that was solid but less saturated than butter. Margarine began to replace butter in shopping carts and labels on baked goods hyped that they were made with vegetable shortening.
By the early 1990s, there were suggestions that we may have gone from the frying pan into the fire. “Partial hydrogenation” also had an effect distinct from converting double bonds into single ones. Normally the carbon atoms attached to those involved in the double bond are on the same side of the double bond in what is referred to as a “cis” configuration. Hydrogenation can alter the geometry of the double bond so that the attached carbon atoms end up on opposite sides of the bond, resulting in “trans” fats. These turned out to be even more capable of causing deposits in coronary arteries than saturated fats! The race to eliminate the dastardly trans fats was on.
Most vegetable oils are liquids at room temperature, but coconut oil, palm oil and palm kernel oil are exceptions, due to their high saturated fat content. Because their saturated fat content is still lower than butter, manufacturers turned to these fats to replace partially hydrogenated fats in processed foods. Palm oil was particularly attractive because it resists degradation when used for frying and has a consistency that is ideal for producing baked goods. And crucially, it is cheap to produce, because the oil palm tree that bears the fruit from which the oil is produced has the highest yield per acre of any oilseed crop. Furthermore, the oil extracted from the kernel of the fruit is high in lauric acid, which can be converted into lauryl alcohol, the key compound for the production of sodium lauryl sulphate, the most widely used surfactant in the world. Surfactants are key ingredients in detergents, forming a link between water and greasy deposits. Sodium lauryl sulphate has the added benefit of dislodging soil from surfaces through its ability to boost foam. More recently, palm oil has been used to produce biodiesel fuel, further increasing demand.
That demand has consequences. Producing more palm oil requires planting more oil palm trees, which requires more land. Unfortunately, in Malaysia and Indonesia, the prime producers, the quest for more planting acreage leads to deforestation, often by setting fire to rainforests. The carbon dioxide released by these fires is a significant contributor to the greenhouse effect, which of course is a concern. But there is another issue. Expanding palm tree plantations, particularly in Borneo and Sumatra, are encroaching on the habitat of wildlife. These are the only two locations where orangutans are still found, and the species is now critically endangered. The same goes for the Sumatran tiger and rhinoceros. Many other rainforest animals may face the same fate as their habitat is replaced by palm trees. Turning away from the use of palm oil is not viable. It is an ingredient in hundreds and hundreds of consumer products, ranging from cookies and cereals to lipstick. However, the oil can be produced in a sustainable fashion on plantations that have not relied on deforestation.
Nutritionists have also raised alarm about consuming foods containing palm oil on account of its saturated fat content, although in recent years the relationship between heart disease and saturated fats has blurred somewhat and these fats may not be quite as villainous as it once seemed. As a general rule, though, palm oil is often found in processed foods, a class that has been linked with ill health and premature mortality.
Now producers of the most widely used vegetable oil in the world may have something else to worry about, given some recent headlines: “Palm oil used in chocolate spreads, cooking oil may fuel cancer spread.” “Palm oil linked to increased cancer risk, study finds.” “Acid from palm oil linked to cancer spread.” Scary stuff, especially considering that the research to which the headlines refer was published in Nature, one of the world’s most respected science publications. However, the headline writers missed a key feature of the study. It was done in mice! Researchers inoculated mice with human squamous carcinoma cells and then fed them a diet high in palm oil or olive oil. Once tumours developed, cells were extracted and transplanted into mice that were fed a standard lab diet. The tumours in this second group of mice that originated in the palm oil-fed mice metastasized much more quickly than the tumours from the olive oil-fed mice.
While this is valuable research in trying to unravel the mysteries of cancer metastasis, it has no direct implication for humans. First, people are not giant mice. Also, the amount of palm oil the mice were fed was far more than that found in the human diet. And there was no demonstration that palm oil had an effect on the growth of primary tumours, only on the ability of the tumours to spread once transplanted to other mice. The paper’s senior author did not claim that the research had direct meaning for people, but opined that patients with metastatic cancer might benefit from a diet poor in palmitic acid. And that might benefit the orangutans as well.
Joe Schwarcz is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.