The cornerstone of the original dietary guidelines was the recommendation to reduce the intake of saturated fat (SFA). This in turn led to the advice to increase the consumption of complex carbohydrates and the polyunsaturated fat (PUFA). The fundamental basis was the so-called “cholesterol theory” which was that the risk of developing heart disease was associated with the levels of total cholesterol (TC) and LDL-Cholesterol (LDL-C) in the blood. The case against SFA was that it pushed up these 2 parameters and therefore lowering it would reduce the risk. Similarly it was argued that the risk would also be reduced by increasing the consumption of PUFA because of its effect on TC and LDL-C.
It is obvious to anyone who examines the evidence in a dispassionate way that it is full of holes. In particular:
- Because the emphasis has been completely focussed on heart disease, the implications for other diseases/conditions have been neglected. The only logical approach is to concentrate on all causes of illness/death. The best indicator of progress (or the lack of it) is all-cause mortality (ACM).
- It emerges that when this is done, the highest death rates are for those with low values of TC and LDL-C. It is quite amazing that in men there is no increase in death rates at high values and surprise, surprise, in older women, which is when most deaths occur, the greatest life expectancy is in those with the highest values (1).
- There has been a failure to recognise the role of the different individual SFAs which vary in their effects on TC and LDL-C. Many of them are important nutrients in their own right (2).
- Similarly there has been no appreciation that increasing the omega-6 PUFAs can be extremely detrimental because of increased inflammation which can lead to many different diseases including cancer and heart disease (3).
- It is virtually certain that the recommendation to increase the consumption of carbohydrates is one of the critical factors which has contributed to increase in the incidence of type 2 diabetes (T2D).
Despite these rather inconvenient facts, the recently approved Dietary Guidelines for Americans (4) continues to point the finger at SFA.
Here is the actual recommendation:
“Limit calories from added sugars and saturated fats and reduce sodium intake. Consume an eating pattern low in added sugars, saturated fats, and sodium. Cut back on foods and beverages higher in these components to amounts that fit within healthy eating patterns.”
The scientific basis was developed by an Advisory Committee which reported earlier in 2015 (5) and relied heavily on a report prepared jointly by a Task Force of the American College of Cardiology and the American Heart Association entitled:
“2013 AHA/ACC Guideline on Lifestyle Management to Reduce Cardiovascular Risk”
It is unbelievable that once again there has been heavy reliance on evidence which is restricted to heart disease. In fact the report specifically states that the objective is:
“to develop clinical practice guidelines for assessment of cardiovascular risk, lifestyle modifications to reduce cardiovascular risk, management of blood cholesterol in adults, and management of overweight and obesity in adults.”
“Outcomes of interest not covered in this evidence review were the following risk factors: diabetes mellitus (diabetes)-and obesity-related measurements, incident diabetes metabolic syndrome, high-sensitivity C-reactive protein, and other inflammatory markers.” (emphasis added)
The fact that T2D, which is probably the most important public health issue at the present time, has been omitted simply beggars belief.
Reverting back to the report itself, it is evident that the “cholesterol theory” remains one of the pillars of the strategy. Even though there is overwhelming evidence that low TC and low LDL-C is associated with high ACM, the AHA/ACC continues to regard any treatment that lowers these values as beneficial with respect to heart disease. It accepts that many people in the USA would benefit from lowering their LDL-C and are advised to:
- Aim for a dietary pattern that achieves 5% to 6% of calories from saturated fat.
- Consume a dietary pattern that emphasizes intake of vegetables, fruits, and whole grains; includes low-fat dairy products, poultry, fish, legumes, nontropical vegetable oils, and nuts; and limits intake of sweets, sugar-sweetened beverages, and red meats.
Essentially this advice has finished up in the approved Dietary Guidelines. What this means is that the vilification of the SFA continues.
There is no doubt that the original American guidelines did enormous damage because they advised a reduction in fat/SFA that helped to increase the consumption of carbohydrates, which is one of the major reasons why T2D is currently such a huge problem. It is a global issue because so many countries took the lead from the USA in the development of national nutrition policies. We have now reached a point where the only effective means of combatting the T2D crisis is to take policy initiatives which will result in a substantial reduction in the consumption of sugar and other carbohydrates. While there is growing recognition that sugar intake should be controlled, there will be little progress until it is accepted that there has to be a corresponding increase in the consumption of healthy fats which includes SFA.
The fact that the USA continues to advocate a sharp reduction in SFA is a set-back which flies in the face of overwhelming evidence.
On the other hand there are many positive signs and there is growing awareness that a fundamental re-think is required in official policies around the world.
Perhaps the most impressive proof comes from Sweden where the national diet has been changing in accordance to these concepts. In fact there was recently a shortage of butter! The incidence of obesity is beginning to decline and I have it on very good authority that T2D is also starting to decline.
The adoption of the US guidelines is just one more example of the inadequacy of policy formulation, which happens in so many countries. It is proving to be extremely difficult to achieve fundamental shifts in concepts. This is probably because governments invariably rely on the establishment “experts”. Most of these have built up their reputations by helping to devise the current strategies. It is quite an eye-opener to discover that so many of the leaders in the medical profession in the USA and elsewhere still apparently believe in the “cholesterol theory” and are quite unaware of (or chooses to ignore) the evidence which destroys its credibility.
A closely related aspect is the ineptness of politicians to exert control and who seem to be incapable of challenging the validity of the advice presented by the medical/health professionals. But that is a story for another day.