Northern Ireland has one of the highest death rates due to heart disease in the world while France has one of the lowest. A comparison between the diets of middle-aged men in Belfast and in Toulouse which was published as long ago as 1995 provides some fascinating insights which are highly relevant to anyone interested in understanding how diet and health/disease are related (1).
The study was part of the WHO MONICA Project which was MONItoring trends and determinants in
CArdiovascular disease in more than 20 countries.
Table 1 shows that there are huge differences in the death rates for men between Belfast and Toulouse. In particular the death attributed to ischaemic heart disease in Belfast is 4 times that of Toulouse. This is also reflected in the all-cause death rate which for 55-64 year old men in Belfast is almost double that of Toulouse.
TABLE 1 DEATH RATES IN BELFAST AND TOULOUSE
| Death rates/100,000 | ||||
| Men aged 45-54 | Men aged 55-64 | |||
| Cause of death | Belfast | Toulouse | Belfast | Toulouse |
| Ischaemic heart | 237 | 56 | 761 | 175 |
| Stroke | 32 | 24 | 130 | 61 |
| Other CVD | 30 | 22 | 130 | 92 |
| Cancer | 188 | 159 | 694 | 515 |
| Injury and poison | 59 | 75 | 67 | 72 |
| Other | 91 | 122 | 330 | 280 |
| All causes | 638 | 459 | 2112 | 1197 |
Consideration of the conventional risk factors for heart disease (Table 2) shows that there is little difference between the 2 communities with respect to Total Cholesterol (TC) and Body Mass Index(BMI). However for diabetes, hypertension and current cigarette smoking the values are higher in Toulouse, especially in the older men. It is particularly significant that the levels of TC are virtually the same. In view of the four-fold difference in the death rate due to ischaemic heart disease this fact is in full agreement with all the evidence which demonstrates that TC is not a critical factor contributing to the development of heart disease. The low death rates despite the higher rates of diabetes, hypertension and cigarette smoking strongly indicates that there must be certain features about living conditions in Toulouse which provide a considerable measure of protection against heart disease.
TABLE 2 RISK FACTORS FOT HEART DISEASE IN BELFAST AND TOULOUSE
| Men aged 45-54 | Men aged 55-64 | |||
| Risk factor | Belfast | Toulouse | Belfast | Toulouse |
| Diabetes(%) | 2.6 | 7.2 | 3.5 | 10.9 |
| Hypertension(%) | 20.6 | 27.5 | 33.5 | 49.0 |
| Cigarette smoker(%) | 32.3 | 35.3 | 22.9 | 36.2 |
| TC(mmol/L) | 6.19 | 5.94 | 6.12 | 5.98 |
| HDL cholesterol(mmol/L) | 1.22 | 1.39 | 1.28 | 1.34 |
| BMI | 26.3 | 26.0 | 26.7 | 26.4 |
Surveys of 80 men in Belfast and 40 men in Toulouse showed that there were marked similarities in the patterns of food consumption(Table 3). Although there is a higher intake of saturated fat (SFA) in Belfast it is unlikely that this would explain the difference. The rationale which underpins the case for reducing SFA is completely dependent on alleged role of cholesterol in heart disease which apart from this study has been discredited (see Blog 8). There was much higher consumption of tomatoes, cabbage, broccoli and carrots in Toulouse but onion consumption was higher in Belfast. Fruit consumption in Toulouse was 3 times that of Belfast.
In the light of our current knowledge the factors which probably explain the relatively low death rates in Toulouse are as follows:
- The much higher intake of linoleic acid, which about 50% greater in Toulouse than in Belfast. Although we have not been given information on the relative amounts of omega-6s to omega-3s the higher intake of linoleic acid in Toulouse suggests a greater relative intake of omega-3s.
- The intake of sugar is much lower in Toulouse than it is in Belfast. The is growing evidence that the combination of glucose and fructose which is produced by the breakdown of sugar when excessive amounts are consumed results in Metabolic Syndrome(2).
- It has now been established that low intake of vitamin D predisposes to a wide variety of diseases including heart disease and many cancers. Because of climate differences the exposure to sunshine, which stimulates the synthesis of vitamin D, is much greater in the South of France than it is in Northern Ireland, low vitamin D status would be virtually non-existent in Toulouse.
- The greater consumption of fruit and vegetables in Toulouse almost certainly help to achieve the favourable standards of health in Toulouse.
TABLE 3 NUTRIENT CONSUMPTION IN BELFAST AND TOULOUSE
| Nutrient | Belfast | Toulouse |
| Total energy (Kcal) | 2340 | 2295 |
| Protein(g) | 62.8 | 96.8 |
| Fat(g) | 99.8 | 92.3 |
| Carbohydrate(g) | 270 | 235 |
| Saturated fat(g) | 42.8 | 35.3 |
| Monosaturated fat(g) | 36.6 | 33.1 |
| Polyunsaturated fat(g) | 12.0 | 17.0 |
| Linoleic acid(g) | 9.6 | 13.8 |
| Alcohol(g) | 12.1 | 21.7 |
| Sugar(g) | 104 | 79.1 |
| Starch(g) | 151 | 143 |
| Fibre(g) | 21.1 | 19.5 |
The results of this study provide valuable support to the growing body of evidence which is challenging the conventional dietary guidelines, which place emphasis on the role of SFA and cholesterol. It is abundantly clear that a very low incidence of heart disease is perfectly compatible with TC levels considered “dangerous” by much of the medical profession.
REFERENCES
- A Evans et al (1995) Quarterly Journal of Medicine 88 pp469-467
- Metabolic Syndrome is the term used for a range of diseases/conditions which include hypertension, obesity, diabetes, raised blood triglycerides and low HDL cholesterol all of which may contribute to the development of heart disease.