LONDON, UK — The contention that dietary saturated fats aren’t the bad guys that policies and guidelines have portrayed for decades has reemerged in the literature, this time in an "Observations" opinion piece in published in BMJ [1].
"The mantra that saturated fat must be removed to reduce the risk of cardiovascular disease has dominated dietary advice and guidelines for almost four decades," according to the author, Dr Aseem Malhotra (Croydon University Hospital, London, UK). "Yet scientific evidence shows that this advice has, paradoxically, increased our cardiovascular risks."
Moreover, he writes, "the government’s obsession with levels of total cholesterol, which has led to the overmedication of millions of people with statins, has diverted our attention from the more egregious risk factor of atherogenic dyslipidemia."
To back his claims, Malhotra cites reports suggesting that:
• Low-saturated-fat diets cut levels of lower-risk large, buoyant LDL particles rather than the small, dense LDL particles thought to worsen cardiovascular disease.
• Dietary saturated fat may actually protect against cardiovascular risk.
• Low-fat diets promote an atherogenic pattern of blood lipids and worsen insulin resistance.
• Low total-cholesterol levels are "associated with cardiovascular and noncardiac mortality, indicating that high total cholesterol is not a risk factor in a healthy population."
• Even in secondary prevention, no cholesterol-lowering drug besides statins has shown survival benefit, supporting the hypothesis that the benefits of statins are independent of their effects on cholesterol.
• The "Mediterranean diet" confers three times the survival benefit in secondary prevention, compared with statins; it led to a 30% improvement compared with a "low-fat" diet in the PREDIMED study.
"It’s risky to pick and choose studies on which to base judgments" and to tell only part of a large story, according to Dr Alice H Lichtenstein (Tufts University, Boston, MA), who directs her center’s Cardiovascular Nutrition Laboratory.
In just one example cited for heartwire , she said that "the PREDIMED trial did show that in high-risk people the Mediterranean diet achieved a 30% improvement over a "low-fat" diet." However, a low-fat diet in PREDIMED meant 37% of calories from fat, not the usual definition. "And the benefit was seen only for stroke, an outcome most closely associated with blood pressure, not plasma cholesterol levels," Lichtenstein said.
She continued, "Based on the totality of the data, the best advice we can give is to consume a moderate-fat diet (25% to 35% of energy) and substitute polyunsaturated fat for saturated fat—that is, vegetable oils for animal fats, including meat and dairy—all within the context of a calorie intake that is consistent with achieving and maintaining a healthy body weight. Given the plethora of food choices currently available, that should not be a difficult task."
[1] Malhotra A. Saturated fat is not the major issue. Let’s bust the myth of its role in heart disease. BMJ 2013;347: DOI:10.1136/bmj.f6340. Available here.
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