Prolongation of life span in hypertensive rats by dietary interventions. Effects of garlic and linseed oil.

The effects of long-term dietary application of garlic (dried powder, 0.5% in weight of standard chow; G group) or linseed oil (2.5%; L group) as well as a combination of both interventions (L + G group) on the life span of hypertensive rats (SHR SP) was investigated. A further group fed with standard chow served as control (C). The dietary interventions were started at the age of three weeks. Besides regular measurements of the systolic arterial blood pressure (oscillometrically at the tail artery) as well as of heart rate and body weight, autopsy and histological investigations were performed. Both diets, and particularly their combination, prolonged life span significantly (mean values (days) C: 434.5 +/- 23.5; G: 453.2 +/- 16.2; L: 470.0 +/- 26.2; L + G: 494.8 +/- 39.2). There was no significant interaction of the factors garlic and linseed oil. Systolic blood pressure as measured during the compensatory stage (data used until the 39th week of life) was significantly lowered by both garlic (mean -5.8 mm Hg), linseed oil (mean -6.3 mm Hg), and their combination (mean -11.3 mm Hg). The animals died as a consequence of congestive left and right ventricular failure with ventricular hypertrophy, dilatation, myocardial fibrosis and cellular infiltration, left ventricular atrial thrombosis (in most cases), and terminal pneumonia. On the other hand, arteriosclerotic plaques and signs of cerebral stroke could not be detected. Except for the degree of hypertrophy, which was lower in the treated groups, no differences were obvious regarding the morphological findings at the time of death. There was a significant positive correlation between mean blood pressure and the degree of left ventricular hypertrophy. Furthermore, a significant negative correlation between mean blood pressure and ventricular hypertrophy on the one hand and survival on the other hand was obvious provided the total number of animals was considered, however, not within the individual groups. The same applies to the relation between the reduction of left ventricular hypertrophy and life span. The relatively slight hypotensive effect of both dietary interventions as well as the results of previous investigations speaks in favor of a substantial influence of factors independent of blood pressure. In view of controversial results and interpretations in international literature, the mechanisms involved need further study.