Recommendations for the management of dyslipidemia and the prevention of cardiovascular disease: summary of the 2003 update

This concerns the dyslipidemia management and cardiovascular prevention review by J. Genest et al, as published on the Internet only [CMAJ Oct. 28, 2003; 169 (9)]. The review deals much with the statin issue but since the 3 most recent large studies, PROSPER, ALLHAT and ASCOT failed to show any all-cause mortality benefit from statins and a 4th, HPS, has not published cumulative mortality data, we shall leave this issue to others after pointing out that the failure to reduce all-cause mortality even in high-risk groups from cholesterol lowering [paraphrase from the ALLHAT website] supports the urgency to explore other routes in secondary and certainly in primary prevention.

As the authors point out, there is much potential in homocysteine lowering with high-dose multi B-vitamins, an approach supported by many hundreds of studies but that still lacks placebo controlled trials. As proposed, we indeed need trials that treat to the suggested 9 µmol/L target or, one may suggest, to a target near 6 µmol/L. To our knowledge, there are no reported fatalities from no-iron containing over the counter multi-vitamins, the only therapy known to lower homocysteine and an urgent issue in the French Canadian population that appears to have a relatively high incidence of genetic enzyme impediments in metabolizing homocysteine.

Other than the above, our main concern with the recommendation is the suggestion to "..increase the proportion of mono- and polyunsaturated fats in the diet while decreasing the proportion of saturated fats..".  All common vegetable oils except olive and canola, e.g. soybean, corn, cottonseed, sunflower and safflower, contain over 50% linoleic acid, a potentially pro-inflammatory omega-6 fatty acid that may already provide 2 or 3x over the ISSFAL proposed maximum of 3% of energy intake [adequate: 2%]. Demonstrated as early as 35 years ago in the Veterans Trial, the replacement of saturated fat and cholesterol with high omega-6 oil did not decrease all-cause mortality but there was an about doubled cancer mortality after 8 and 9 years, a cancer problem also suggested by PROSPER's 24 more cancer deaths in a smaller pravastatin group with fewer smokers. The failure of the trials of dietary fat changes, other than those involving omega-3's, was high-lighted in the meta analysis by L. Hooper et al BMJ 2001.

The recommendation to increase plant-based omega-3 [good sources: canola: 10%, flax oil: 55% and walnut oil: 10%] as well as fish-based omega-3 is clearly well supported, and here we refer to an important omega-3 editorial by A. Leaf in Circ.1999;99:733-735. However, and in summary, the vast majority of store-shelf poly-unsaturates are of the relatively pro-inflammatory omega-6 family of fatty acids and of which an increased consumption is not supported by controlled trial data.

[all hyperlinks accessed 27-11-2003]

Eddie Vos (corresponding) www.health-heart.org Sutton (Qc) J0E 2K0 vos@health-heart.org
Colin Rose, M.D., cardiologist, Montreal (Qc) colin.rose@mcgill.ca

Conflict of Interest:

None declared