A UK cardiologist says it is time “to bust the myth of the role of saturated fat in heart disease,” pointing out that since we started following advice to remove it from our diets, cardiovascular risk has gone up.
Writing in this week’s online issue of the British Medical Journal Aseem Malhotra, an interventional cardiology specialist registrar at Croydon University Hospital, London, also says government obsession with reducing total cholesterol has led to millions of people being overmedicated with statins, when the real issue is not cholesterol but a more complex triad of lipid abnormalities called “atherogenic dyslipidemia.”
He describes how the “seven countries” landmark study of the 1970s, showed links between rates of coronary heart disease and cholesterol levels, and linked this to energy levels from saturated fats. But without establishing whether these factors were actually causing heart disease, governments pushed out guidelines telling us to cut fat intake to 30% of total calories and saturated fat to 10%.
In the meantime, “recent prospective cohort studies have not supported any significant association between saturated fat intake and cardiovascular risk,” and “Instead, saturated fat has been found to be protective,” he adds.
Dr. Malhotra points the finger at sugar. When you take the fat out of food, it tastes worse, so the food industry replaced the saturated fat with added sugar.
Now evidence is piling up showing that sugar could be an independent risk factor for metabolic syndrome (a cluster of conditions that includes high blood pressure, abnormal blood sugar, raised triglycerides, low cholesterol and a large waist), which is known to lead to diabetes and raised cardiovascular risks.
Another failure in the argument demonizing saturated fat is the idea that because it is energy-rich, then reducing it will reduce calorie intake. But, setting aside the fact that food producers substituted it with sugar, this argument clashes with increasing evidence to back the theory that a “calorie is not a calorie” – where that energy comes from can determine how much energy is consumed.
Fat has more energy per gram than protein and carbohydrate, but Dr. Malhotra cites studies that show the body does not metabolize these nutrients in the same way; indeed, among weight loss diets comprising 90% fat, 90% protein and 90% carbohydrate, the greatest weight loss was in the 90% fat group.
In the past 30 years, he notes, Americans have dropped the proportion of energy intake from fat from 40% to 30%, yet “obesity has rocketed.”
Another important concern is where the saturated fat comes from. For instance, dairy foods are high in fat, but they also provide vitamin A and vitamin D and essential minerals, such as calcium and phosphorous. Low levels of vitamin D can be a major cause of high blood pressure, and has also been linked to increased risk of death from cardiovascular conditions.
There is also evidence that a fatty acid mainly found in dairy goods is linked to higher levels of high density lipoprotein (the “good” cholesterol that helps fight heart disease), reduced insulin resistance and other protective factors.
Meat is also a rich source of saturated fat, and while processed meat has been linked to raised risk of coronary heart disease and type 2 diabetes (perhaps because of its high nitrates and sodium content), red meat has not.
Statins, taken for lowering total cholesterol, are now the second most commonly prescribed drugs in the US, thanks to the powerful influence of the Framingham heart study which, among other things, pointed to total cholesterol as a risk factor for coronary artery disease.
But, says Dr. Malhotra, take for example in the UK, where 60 million prescriptions for statins are filled every year, there is no evidence that they have reduced cardiovascular deaths more than can be accounted for by the reduction in smoking and life-saving treatments like angioplasty.
And, he points out, although in the past cardiosvascular disease used to occur mostly on its own, today, two-thirds of people who end up in hospital following a heart attack have metabolic syndrome, yet 75% of them have normal cholesterol levels.
More evidence perhaps, that total cholesterol is not the culprit, he suggests.
The longer a drug is used by more and more patients, the more opportunity there is to compare what happens in the population at large with the results of the clinical trials that led to the drug’s approval.
In the case of statins, what is emerging is a sharp contrast between the results of the original clincal trials and the “real word” experience.
While clinical trials found only 1 in 10,000 patients given statins experienced a minor side-effect (0.01%), a study of 150,000 patients prescribed statins by their GP, showed 20% had such “unacceptable” side effects they stopped taking them. The side effects included stomach upsets, muscle pains, sleep and memory disturbance, and erectile dysfunction.
Dr. Malhotra says the strongest evidence in support of statins is to prevent second heart attacks, where patients receive the maximum dose, regardless of their total cholesterol levels. This is because statins are good at stabilizing coronary plaques and reducing inflammation in blood vessels.
“The fact that no other cholesterol lowering drug has shown a benefit in terms of mortality supports the hypothesis that the benefits of statins are independent of their effects on cholesterol.”
Dr. Malhotra advocates adopting a Mediterranean diet – this has been shown to be three times as effective at reducing cardiovascular deaths as statins. Even compared with a low fat diet, a recently published trial showed that in high risk groups, a Mediterranean diet reduces cardiovascular events.
A traditional Mediterranean diet is high in olive oil, fruit, nuts, vegetables, and cereals, contains moderate amounts of fish and poultry and low amounts of red and processed meats, dairy foods and sweets. Wine is drunk in moderation and only with meals.
Dr. Malhotra urges doctors to “embrace prevention as well as treatment.” Drugs can alleviate symptoms but they can’t change the “pathophysiology,” he says, and concludes:
“It is time to bust the myth of the role of saturated fat in heart disease and wind back the harms of dietary advice that has contributed to obesity.”
Update May 15, 2014 – BMJ authors withdraw statements about adverse effects of statins.