Available evidence from randomized controlled trials shows that replacement of saturated fat with linoleic acid effectively lowers serum cholesterol but does not produce a lower risk of death from coronary heart disease. In fact, replacing fats with unsaturated fatty acids increases the risk of coronary heart disease, because these fatty acids rapidly undergo oxidation. In their oxidized, radical, form they do more harm than good. However, unsaturated fatty acids do play beneficial roles in human health but they must be protected against oxidation, for instance by taking vitamin E and OPCs.
Table of contents
- You’re avoiding fat for no good reason
- Lack of benefits of lowering cholesterol confirmed
- The traditional diet-heart theort is debunked
- Did the Minnesota intervention lower serum cholesterol ?
- Did the MCE intervention reduce risk of death?
- Why doesn’t lowering serum cholesterol produce a clinical improvement ?
- Are unsaturated fatty acids essential nutrients ?
You’re avoiding fat for no good reason
What if I told you that the idea to replace saturated fat with vegetable oils containing unsaturated fatty acids, such as linoleic acid, will reduce coronary heart disease has never been scientifically proven. What if I told you that a large dietary study performed in the United States showed that replacing fats by vegetable oils actually increases the risk of developing a cardiovascular condition and premature death. What if I told you that replacing saturated fat by vegetable oils does reduce your serum cholesterol level, but that, evidently, this does not produce a lower risk of death from coronary heart disease or all other causes. What if I told you that this large American dietary study that debunks the cholesterol-heart myth that lowering cholesterol will reduce coronary heart disease was performed between 1968 and 1973 and that, for unknown reasons, it has remained unpublished for almost 50 years until, in 2016, a group of scientists evaluated and published the original data. ([I])
Lack of benefits of lowering cholesterol confirmed
What if this means that this study’s incomplete publication has contributed to an unwarranted and counterproductive overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid. What if this means that for more than half a century millions of people have been taken completely unnecessary and perhaps even harmful dietary measures. What if a study performed during that same period in Australia confirmed the outcomes of the American study, and that this study was also not published until the same investigators performed an in-depth analysis of the original data in 2013. ([ii])
The traditional diet-heart theort is debunked
According to the investigators, the traditional cholesterol-heart hypothesis predicts that replacing saturated fat with vegetable oils rich in linoleic acid will reduce cardiovascular deaths by lowering serum cholesterol. This proposition has never been causally demonstrated in a randomized controlled trial and thus has remained uncertain for over 50 years. Key findings from landmark randomized controlled trials including the Australian Sydney Diet Heart Study and the American Minnesota Coronary Experiment (MCE) were not fully published. Though the MCE intervention lowered serum cholesterol, this did not translate to improved survival. Paradoxically, MCE participants who had greater reductions in serum cholesterol had a higher, rather than lower, risk of death. Results of a systematic review and meta-analysis of randomized controlled trials do not provide support for the traditional diet heart hypothesis
Did the Minnesota intervention lower serum cholesterol ?
In the 2016 publication, the evaluators reported how the MCE investigators had hypothesized that replacing saturated fat with vegetable oil rich in linoleic acid would lower serum cholesterol in a manner consistent with the established method of measuring. As predicted, participants in the intervention group did significantly lower serum cholesterol compared with the control group and compared with their cholesterol level at the beginning of the study. The lowered serum cholesterol that was observed in participants in the entire intervention (linoleic acid) group was equally observed in each of the subgroups defined by sex and age. Among the intervention group, higher adherence (fewer missed meals) was associated with a more pronounced reduction in serum cholesterol.
Did the MCE intervention reduce risk of death?
Briefly put, the most complete analysis comparing mortality in the intervention versus control group confirmed that a dietary shift from saturated to unsaturated fats produced no “mortality benefit.” Moreover, the study’s records showed that in the sub-group aged 65 and older the intervention group ran a higher risk of coronary heart disease when compared with the control-group that had consumed a balanced saturated-unsaturated fats diet. The traditional diet heart hypothesis predicts that participants with greater reduction in serum cholesterol will have a lower risk of death. However, the number, proportion, and probability of death increased as serum cholesterol decreased. In survival analyses, there was a robust association between decreasing serum cholesterol and increased risk of death. Among participants who were older than 65 at baseline, a 30 mg/dL decrease in serum cholesterol was associated with 35% higher risk of death, whereas among people aged under 65 at baseline there was no relation between the change in serum cholesterol and death.
Why doesn’t lowering serum cholesterol produce a clinical improvement ?
As correctly noted by the investigators, “consumption of vegetable oils and food products rich in linoleic acid produces a wide range of biochemical consequences, including qualitative changes in cholesterol oxidation that could plausibly increase risk of coronary heart disease.” Hence, the potential benefits of replacing saturated fat with vegetable oils could very well be offset by their susceptibility to oxidation. This is especially relevant in modern diets that tend to provide a larger than normal quantity of unsaturated fatty acids provided by natural foods. An excess of fatty acids means an excess of oxidized cholesterol. Moreover, low density (“bad”) cholesterol (“LDL”) is influenced by many factors, such as its delivery to blood vessels and other tissues, as well as clearing native and oxidized forms by the liver.
Are unsaturated fatty acids essential nutrients ?
The investigators explain that “a decrease in low density lipoprotein [LDL] can represent widely different biochemical phenomena.” They also conclude that the data from all the diet-heart trials that they gathered “suggest that lowering serum cholesterol by replacing saturated fat with vegetable oils rich in linoleic acid has no clear benefit. Further, one way to interpret the unfavorable results of the two recovered trials is that high intakes of linoleic acid could have adverse effects in people who are prone to linoleic acid oxidation (such as smokers, heavy drinkers, and older adults).”
Indeed, these oxidized fatty compounds have been implicated as the cause of many diseases including coronary heart disease, chronic pain, and inflammation of the liver. Does this mean that we should avoid vegetable oils ? Of course not. Unsaturated fatty acids play many important roles in the human body, which is why they are sometimes called essentialfatty acids. But, in their oxidized form, they do more harm than good. So, the solution is quite simple. Protect them against oxdiation by taking vitamin E and OPCs. Not just any undefined or unqualified “OPC,” but the OPCs developed by professor Jack Masquelier.