The Lyon Heart Study is one of the most successful investigations which demonstrate that a change in diet results in a significant improvement in the survival rates of men and women aged <70 years old who have experienced a heart attack.
Volunteers who had survived a heart attack were allocated to either a control group (n=303) or an experimental group(n=302). Those in the experimental group were advised to consume a Mediterranean type diet which involved a reduction in the consumption of total fat, saturated fat and linoleic acid (omega-6s) and an increase in the consumption of oleic acid and alpha-linolenic acid (omega-3s). The participants were seen 8 weeks after the beginning of the trial and then again every year for up to 5 years.
At the first follow-up (minimum period 1 year) it was found that those on the Mediterranean diet had a much better chance of survival than those in the control group. As a consequence the decision was taken to stop the trial so that those in the control group were free to make changes to their diet and follow the advice given to the experimental group if they so wished. Nevertheless the research team continued with the original plan and a final assessment of all existing participants was done after about 4 years.
The results(Table 1) show that the death rate attribute to heart disease has been reduced by 65% in those consuming the Mediterranean diet while the all-cause death rate has been reduced by over a half. Because of the decision to effectively halt the trial after the first year this means that almost certainly these values are an under estimate.
TABLE 1 DEATH RATES IN THE CONTROL AND EXPERIMENTAL GROUPS
|Cause of death||Number||Rate||Number||Rate||Relative Rate|
Note: The rates are given per 100 patients per year of follow-up; they were calculated from a follow-up of 1383 and 1467 person-years for mortality in the control and experimental groups, respectively.
The diets of the 2 groups are shown in Table 2. In any investigation of this type it is difficult to identify which particular changes in diet have contributed to the very significant improvements in the prospects of the experimental group which have been observed.. The increase in omega-9s was largely due to increased consumption of olive oil. There was also a reduction in the intake of omega-6s and an increase in that of the omega-3s. The net effect of this was to reduce the omega-6:omega-3 ratio from 18.3 to 4.3. In the light of our existing knowledge the authors considered that this was the critical factor.
TABLE 2 NUTRIENTS IN THE CONTROL AND EXPERIMENTAL GROUPS
|Total fat,% E||33.6||30.4|
There is no question that the results of this investigation are absolutely outstanding and clearly demonstrate the huge benefits that can be achieved by making changes to the habitual diet. It is relevant to compare these results with those obtained using statins. Table 3 has been complied with information in Anthony Colpo’s excellent book (2). A recent report by the Cochrane Collaboration combined the results from 13 different trials involving 48,060 participants. It was found that in the statin groups there were 1077 deaths out of 24,408 participants (4.1%) compared with 1223 deaths in 23.653 in those given a placebo(5.1%)(3) It is evident that although there are some reductions in the death rates due to both heart disease and to all causes, these do not compare with those which were found in the Lyon Heart Study.Although it is generally agreed that statins are beneficial to those who suffer from heart disease there is considerable doubt about the use of statins as a primary prevention measure (ie for those who do not have symptoms of heart disease). Furthermore there is absolutely no indication that side-effects arise associated with a Mediterranean type diet. By contrast there is growing evidence that the use of statins is associated with a extensive of side-effects ranging from muscle pains to memory loss.
TABLE 3 EFFECT OF STATIN TREATMENTS ON DEATH RATES DUE TO CARDIAC DISEASE AND TO ALL CAUSES IN SELECTED TRIALS
|Trial||Cardiac death rates, %||All-cause death rates, %|
- Men aged 55 years old or less with hypertension
- Elderly men and women with coronary disease or increased risk due to smoking, hypertension or diabetes
- Hypertensive men and women with at least 3 risk factors for coronary disease
- Men and women heart patients with high cholesterol
- Healthy men with high cholesterol
- Men and women with heart disease or diabetes.
Another highly important finding of the Lyon Heart Study is that at the final assessment the total cholesterol levels (TC) in both groups were virtually identical at just over 6mmol/L. This means that the very large reductions in deaths rates were not dependent in any way on lowering the TC and totally undermines the advice issued by the NHS which recommends that TC levels should be less than 5mmol/L.
If we accept the validity of the Lyon Heart Study results then it is obvious that relatively simple changes to the diet can produce significant improvements to public health. These are relatively easy to make and are much superior to existing policies which are heavily dependent on the use of cholesterol-lowering drugs such as statins.
- M de Lorgeril et al(1996) Journal of the American College of Cardiology 28 (5) pp 1103-1108
- Anthony Colpo(2006) “The Great cholesterol Con: Why everything you have been told about cholesterol, diet and heart disease is wrong!”Amazon Marston Gate ISBN 978-1-4303-0933-8
F Taylor et al (2013) Cochrane Library John Wiley & Son 5 pp 1-96