Heed the Study – Not the Commentaries

April 26, 2016 in Health, Health Claims, Nutrition by Joyce Bunderson

A new study recently published in the British Medical Journal (BMJ) is being used by journalists in secondary reporting to support a current attempt to challenge the known dangers of foods high in saturated fats. While the BMJ study reduced saturated fats in a large (9700 patients in Minnesota Hospitals and Care Centers), more, not fewer people in the group that reduced saturated fats died over a year period. A careful reading of this article shows that the work of Ancel Keys, whose work on the Mediterranean Diet has been featured in these pages, was supported. Keys developed an equation and model showing that the less saturated fat you eat, the lower your cholesterol will go, and the lower your cholesterol, the lower your risk of disease and death from heart-related problems.

The data on this large study was not fully published when it was done 40 years ago, because more people died, and negative results are not often published, even when it later turns out that they should be published. The old data tapes were found and the analysis and write up were redone and published for the first time. The authors do not talk about the role of saturated fat, only of the vegetable oil and its constituent, linoleic acid. The more linoleic acid that was used to replace saturated fats in the patients’ diets, the more cardiovascular events and deaths resulted. This does not say that it would be better to replace linoleic acid with saturated fat; it says that something at the molecular level in the extra linoleic acid was leading to more deaths. This important result should surely have been published earlier. Perhaps modern methods of analysis shed more light, along with greater knowledge of the long-chain linoleic acid molecule, and what happens when it oxidizes.

My problem is with journalistic reports on this article that talk about how less saturated fat leads to more deaths. This is a serious misinterpretation of the study, and may be motivated to support current efforts to rehabilitate saturated fats, and the meat and cheese products that provide them. Consider a few thoughts.

  • The fact is that Ancel Keys looked at diets in the Mediterranean region because those people were living longer healthier lives than Americans. Keys used correlation work to discover that something was going on and he was trying to discover what it was. He found some big differences.
  • We still today benefit from recognizing the differences between the Mediterranean style of eating and the American way. Keys discovered that the Mediterranean peoples’ diet had infrequent consumption of red meat and cheese; and it included abundant “verdure” as he called it - greens. They ate lots of vegetables; fruits and whole grains about 60 years ago, when Keys field studies were done. The journalistic misinterpretations of the BMJ study could lead some people to think that saturated fats in these foods Keys studied are not a problem. The point is that thousands of studies have been done since that time; they point us to increasing plant –based eating. In essence, more vegetables, whole grains and less animal protein foods. Eventually, we will know precisely what is causing cardiovascular disease. The current attempts to rehabilitate the image of red meat and cheese are not supported by this evidence. There is no warrant to start to consume a steak or burger every day along with a thick coating of butter on a slab of garlic bread.
  • Sixty years ago, science did not really know that hydrogenating vegetable oil, created trans fats. So changing from saturated butterfat to partially saturated vegetable fat was not a health benefit. This new study did recommend looking further at oxidized linoleic acid as a causal factor in some diseases – think free radicals. It did not recommend eating more saturated fat instead of that particular component of vegetable oil.
  • When the peoples of the Mediterranean wanted to ‘butter up’ their bread, they dipped it in a little olive oil and vinegar. Strictly speaking, olive oil is fruit oil – olives are technically fruit – not vegetables. I don’t know if that makes any kind of difference, but I do know that olive oil has been used for human consumption for at least eight millennia. It has saturated fat; but is mostly monounsaturated fat. Many of the new vegetable oils are relative newcomers to humans – cottonseed oil; corn oil; canola oil; soybean oil; sunflower; safflower; coconut and palm to name a few.
  • There is a plethora of evidence that eating food high in saturated fat, like red meat and cheese is correlated with a higher incidence of cardiovascular disease. This new research seems to have uncovered something regarding oxidized linoleic acid; it did not discover that saturated fat is a healthy choice. But the point is that there is SOMETHING in red meat that is antagonistic to our cardiovascular health; it might be saturated fat, or it might be something else. And in addition, there may be something in vegetable oils that is also antagonistic to our cardiovascular health. Meanwhile, until we learn the exact mechanisms and substrates, we should probably think twice about eating lots of foods with saturated fats; or, with a surplus of vegetable oils.
  • The authors of the BMJ study showed that we should be concerned with excess lineoleic acid in the vegetable oils, especially when oxidized. We definitely don’t know all the answers – we don’t know exactly what’s going on. But we do know that foods high in saturated fat are strongly associated with cardiovascular disease. Maybe consider getting a greater proportion of your saturated fats from olive oil, which is associated with cardiovascular health.
  • Sometimes when I read a publicity piece and/or arguments for consuming saturated fat, I wonder if the beef industry or the dairy industry is funding it. Just sayin.’

The BMJ study does a thorough review of an old study and gives a strong validation that replacing saturated fat with vegetable oil reduces cholesterol, just as Ancel Keys predicted. Problem is, more people died. But I’m not ready to ratchet up my intake of animal products that provide a rich source of saturated fats just because current publicity is trying to make is sound harmless or even good for you.