According to the latest report prepared for the British Heart Foundation there is not enough evidence to support the current dietary recommendations to reduce saturated fat(SFA) and increase polyunsaturated fats (PUFA) in order to reduce the risk of heart disease(1).
This finding should come as no surprise to anyone who has bothered to keep up to date with the existing scientific literature.
For example, in 2010, the results of another analysis found that there was:
“no significant evidence to conclude that dietary saturated fat(SFA) is associated with an increased risk of CHD, stroke or CVD”
There is also extensive evidence that many of the individual fatty acids play a vital role in the body. Further support is provided by the finding in the study that margaric acid, a saturated fat in milk and dairy products, was associated with lower cardiovascular risk.
Further details on my blog (2).
With respect to the PUFAs the evidence that they are beneficial does not stand up to examination. Products containing PUFAs are rich in omega-6 fatty acids and therefore increasing consumption increases the ratio of omega-6:omega-3 (the type found in fish oils) fatty acids. Up to about 1900 the diet contained approximately equal amounts of each group. However as industrialisation has progressed the intake of the omega 3s has fallen while that of the omega 6s has increased with the result that the ratio of omega 6:omega 3 is now 15-40 in countries such as the USA and the UK. This high ratio can be damaging to health. Ideally this ratio should be about unity and certainly no higher than 4 (3).
In fact, a number of the omega-6 polyunsaturated fatty acids, commonly found in vegetable oils and processed foods, may actually pose risks according to the study.
Furthermore the researchers did find a link between trans fats, the now widely maligned partially hydrogenated oils(trans fats) that had long been added to processed foods, and heart disease. One of the reasons why SFAs have been vilified in the past is due to the failure to distinguish between the trans fats and the SFAs. As a consequence the ill-effects of the trans fats have been wrongly attributed to the SFAs.
In an interview the lead researcher Dr Rajiv Chowdhury pointed out the need to appreciate that there are different types of LDL-Cholesterol (the so-called “bad” one). It is the small dense particles which are dangerous because they are easily oxidised and are more likely to cause inflammation and so contribute to the build-up of plaque inside the arteries. Crucially, these particles are not increased by SFA but by sugary foods and excess carbohydrates. In his view:
“It’s the high carbohydrate or sugary diet that should be the focus of dietary guidelines. If anything is driving your low-density lipoproteins in a more adverse way, it’s carbohydrates.”(4).
Despite this comment, which appeared in the New York Times the BHF could not resist putting their own spin on the research by making this statement on their website:
“We know there are good biological reasons for encouraging a Mediterranean-style diet, where we eat more unsaturated than saturated fat, that lower our levels of ‘bad’ LDL cholesterol” (5)
This conveniently ignores the important fact that not all LDL-Cholesterol is the same and that the small dense ones which cause the damage are not increased by the SFA.
The justification for recommending that SFA should be reduced and that PUFAs should be increased quite simply does not exist. The cholesterol theory has been totally discredited yet the public health bodies, the medical profession and governments continue to rely on it (6,7). The reality is the fundamental issue is the increasing consumption of sugar and refined carbohydrates, which explains why obesity, diabetes and related diseases/conditions are increasing. To his credit Dr Chowdhury recognizes that it is the carbohydrates, not the SFA which are a critical factor in the development of heart disease.
While there is nothing new about these findings it will definitely have been worthwhile if it forces the medical and public health to re-assess their position on the dietary recommendations, especially in regard to the different types of fat.
Finally this report completely demolishes the rationale which underpins the Government Responsibility Deal with respect to SFA. According to the official website:
“Recognising the role of over-consumption of saturated fat in the risk of premature avoidable mortality from cardiovascular and coronary heart disease, and public health recommendations to reduce saturated fat consumption (to less than 11% of food energy for everyone over 5yrs of age, compared to current levels of 12.7%):
We will support and enable people to consume less saturated fat through actions such as product/menu reformulation, reviewing portion sizes, education and information and incentivising consumers to choose healthier options. We will monitor and report on our actions on an annual basis. Progress in reducing people’s saturated fat intakes will be measured via the National Diet and Nutrition Survey.”(8).
In the light of recent developments it is essential that this responsibility Deal is thoroughly re-evaluated as it is no longer credible. Ministers might usefully consider what has happened over the past 40 or so years. The National Food Survey shows that the intake of SFA had fallen from 56.7 g/day in 1969 to 29.2 g/day in 2000(9).
In 1984 the official Committee on Medical Aspects of Food Policy (COMA) recommended that the SFA intake should be reduced from 20% of food energy to 15% as part of a strategy to reduce cardiovascular disease (10). This target was reached by 2000(11). Currently the amount of SFA in the British diet is 12.7% of energy. Over this period the incidence of obesity has continued to increase. In men it has doubled since 1993, which is when detailed information was first collected (12). What is especially disturbing is that since 1994 the incidence of diabetes has more than doubled for both men and women (13).
The Responsibility Deal with the food industry aims to reduce the SFA level even more to 11% of energy in the hope and expectation that there will be a reduction in “ the risk of premature avoidable mortality from cardiovascular and coronary heart disease”(14). As it is evident that reducing SFA has not delivered the expected results in the past, why on earth should anyone believe that the same strategy will work in the future?
- Department of Health and Social Security (1984) “Diet and Cardiovascular Disease” London: HMSO
- Health Survey of England 2010 Adult Trend Tables
- Health Survey for England 2009