The saturated fat and cholesterol theory of cardiovascular disease dates back to a prospective epidemiological study called the seven countries study published by Ancel Keys in 19661. Data from this and subsequent papers was used to construct a theory based on the premise that diets high in animal fats and cholesterol were the cause of atherosclerotic plaques, which lead to cardiovascular disease. However, methodological flaws in this paper and others have been identified, and improvements in our understanding of the molecular biology of cardiovascular disease have challenged the idea that dietary saturated fat and cholesterol are independent risk factors for cardiovascular disease. Further, the recognition of other nutritional factors in the aetiology of cardiovascular disease have serious damaged the theory by adding confounding variables. Deficiency of the essential fatty acid α-linolenic (ALA, C18:3 (n-3)) acid is one such factor that may increase risk of cardiovascular disease.
Epidemiological studies have indicated that ALA is inversely associated with coronary artery disease and inversely associated to risk of myocardial infarction. Research published in the American Journal of Clinical Nutrition in 20032 investigated the association between dietary ALA and the presence of atherosclerotic plaques. Based on data collected from 1575 individuals in the study, dietary ALA was associated with a lower prevalence odds of carotid plaques and with reduced thickness in some areas of the carotid intima-media. The benefits of ALA is also suggested by data from research based on subjects from India3. In Northern India, cooking oil is mainly in the form of mustard oil (Brassica juncea) produced from rape seed, a member of the crucifer family. This oil is rich is ALA, consumption of which shows a lower risk of ischemic heart disease in Indians when compared to consumption of sunflower oil.
While mustard seed oil and its ALA content may be protective of cardiovascular disease, it is worth considering that other nutritional factors in the oil may be the cause of the cardioprotective effects. For example, vitamin E is known to be protective of cardiovascular disease and present in vegetable oils in high amounts. That said, mechanisms are know that explain the possible beneficial effects of ALA on cardiovascular disease, such as the anti-aggregating effects seen on blood platelets It is also known that ALA is metabolised to other long chain fatty acids, most notably eicosapentanoic acid (EPA, C20:5 (n-3)) and docosahexanoic acid (DHA, C22 (n-3)) which are both known to inhibit inflammation and are protective of cardiovascular disease. The benefits of a Mediterranean diet may come in part from the higher intakes of ALA, EPA and DHA associated with the foods frequently consumed.
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