Dietary Reference Intakes (DRI), Report 6, Part 2 : Total fat, fatty acids, and cholesterol

B. Gaßmann, Bergholz-Rehbruecke

Because the data available are insufficient to fix a certain level of fat intake at which the risk of inadequacy is avoided on the one hand and chronic disease prevented on the other, neither an Adequate Intake nor a Recommended Dietary Allowance (RDA) is specified for total dietary fat. However, based on evidence suggesting a risk for obesity and coronary heart disease (CHD) at a low intake of fat in combination with a high intake of carbohydrates, and also at a high intake of fat, Acceptable Macronutrient Distribution Ranges (AMDR) for fat and cabohydrates have been estimated to be for adults 20–35 % of dietary energy for fat and 45–65 % for carbohydrates. A Tolerable Upper Intake Level (UL) is not set for total fat because there is no defined intake level beyond which adverse effects must be expected.

Saturated fatty acids are synthesized by the human organism to ensure adequate amounts needed for physiological and structural functions. Neither an AI or RDA is set, nor an UL has been calculated, because an incremental increase in saturated fatty acid intake increases the risk of CHD. The human body also produces n-9 monounsaturated fatty acids, which are assumed to play no independent role for human health. Accordingly, they need not be strictly contained in human diets, and an AI or a RDA has not been defined. An UL cannot be set in view of insufficient data.

Linoleic acid is an essential n-6 polyunsturated fatty acid and serves as a precursor to eicosanoids. An AI of 17 g/day for men and 12 g/day for women is based on the median intakes in the United States, and an AMDR of 5 to 10 percent of energy has been estimated.

Of the n-3 polyunsaturated fatty acids only &945;-linolenic acid is essential. The AI for &945;-linolenic acid which is also based on the median intakes in the United States is 1,6 g/day for men and 1,1 g/day for women. An AMDR has been estimated to be 0,6 to 1,2 percent of energy. There is insufficient evidence to set an UL for n-3 polyunsaturated fatty acids. Based on the limited studies in animals and humans, a ”reasonnable” linoleic : &945;-linolenic acid ratio of 5 : 1 to 10 : 1 has been recommended. Approximately 10 % of the latter may be replaced by longer-chain n-3 fatty acids.

Similar to saturated fatty acids, there is a positive linear trend between trans-fatty acid intake and cholesterol intake as well and LDl plasma cholesterol concentration. This means an increased risk of CHD. But no UL is set, neither for trans fatty acids nor for cholesterol.

Both DRI and D-A-CH reference values for nutrient intakes are intended to lower the rise of cardiac infarction by higher intakes of unsaturated acids and lower intakes of saturated and trans-fatty acids keeping the number of adequate daily calories constant. DRI and D-A-CH reference values, however, start from different positions and use different concepts.

Keywords: Dietary Reference Intakes 2002 / total fat, fatty acids, cholesterol / comparison with German, Austrian, and Swiss (D-A-CH-) reference intakes of nutrients 2000. EU04/03

Sie finden den Artikel in deutscher Sprache in Ernährungs-Umschau 03/03 ab Seite 128.