A systematic review 1 including 19 RCTs with a total of 8,550 subjects was abstracted in DARE. The diets were classified into 4 types:
- Diet type 1: less than 30% of total energy intake as fat, with 8 - 10% as saturated fat, ratio of polyunsaturated to saturated fat (P/S) greater than 1.0, cholesterol intake less than 300 mg/day, energy intake to achieve desirable body weight.
- Diet type 2: As above, but 7% or less as saturated fat, P/S greater than 1.4, cholesterol intake less than 200 mg/day.
- Diet type 3: Diet to increase the P/S ratio with little or no change in total fat content.
- Diet type 4: Low total fat diets, without changing the proportions of the different fats consumed.
Overall weighted mean reduction in blood total cholesterol concentration across all dietary comparisons was 5.7% (95% CI 5.2% to 6.3%). For diet type 1 the reduction was 3.0% (95% CI 1.8% to 4.1%), for diet type 2 it was 5.6% (95% CI 4.7% to 6.5%), for diet type 3 it was 7.6% (95% CI 6.2% to 9.0%), and for diet type 4 it was 5.8% (95% CI 3.8% to 7.8%).
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