It is about forty years since the dietary guidelines were introduced in USA. Most other countries followed suit. Here in the UK, the report by the Committee on Medical Aspects of Food Policy (COMA) on “Diet and Cardiovascular Disease” in 1984 focussed on fat (1). It recommended that total fat and saturated fat (SFA) should be reduced but that the polyunsaturated fat (PUFA) be increased. The big problem is that it was at about that time, the incidence of obesity and diabetes started to increase. Even the most ardent advocates of these recommendations accepted that the available evidence fell short of proof that their implementation would definitely be effective.
The MRFIT study
Round about that time, I was fortunate to have the opportunity to attend a number of international nutrition conferences, where the introduction of the dietary guidelines was a hot topic in discussions that often continued into the early hours. It is interesting to recall that many of those ardent advocates of the advice to reduce fat and SFA accepted that the evidence to justify the recommendations was not conclusive. However I was assured that proof would soon be forthcoming because there was a massive investigation under way, which assuredly produce the proof that was required. This was the Multiple Risk Factor Intervention Trial (MRFIT) (2).
The work started out with 350,977 men aged 35 to 57. Participants were screened and eventually 12,866 at high risk of heart disease were selected. In the trial, one group was subject to Special Intervention (SI), as participants were treated for high blood pressure (BP), counselled to stop smoking cigarettes and given dietary advice to lower their TC.
The other group was limited to Usual Care (UC) and acted as the control. Despite all the hype, the design was fatally flawed because if the SI proved to be successful, we would still not know whether this was due to one specific intervention or a combination of two or all three.
The trial lasted seven years and at the end of the period the SI group had a small reduction in the death rate due to heart disease. The results reported in 1982 showed that for all-cause mortality (ACM) it was slightly higher in the SI group (41.2/1,000) compared to the UC group (40.4/1,000).
Oh dear! This was a catastrophe. At least, that is what one would expect from any competent, objective investigator. Not a bit of it. The researchers simply brushed aside the failure and continued to monitor the participants after the trial had finished.
After a further four years there was actually a reduction of 9% in the ACM of the SI group. This could well have been due to the reduction in cigarette smoking, which was recorded for the SI group and is known to take some years for the benefit to take full effect. It is highly unlikely to have been the result of the dietary changes as a positive response would be expected in much less than seven years.
The Helsinki Businessmen Study
Thus study was based on men born between 1919 and 1934. Once again, there is a control group with usual care and a special intervention group (SI), which was carefully monitored. Each member of this group was given advice on lifestyle modification on diet, exercise, smoking and alcohol. They were also subject to treatment with drugs including diuretics and beta-blockers for hypertension as well as clofibrate and probucol to lower cholesterol.
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