Dietary fats
A position statement from the Heart Foundationís National Nutrition and Metabolism Advisory Committee
The following recommendations are primarily based on the relationship between dietary fat intake and
well-established clinical endpoints for cardiovascular disease (CVD).
These include coronary heart disease (CHD) events [non-fatal myocardial infarction (MI)], death from
CHD and stroke. The relationship between dietary fat and serum lipids,
overweight, insulin resistance, blood pressure, arrhythmia and thrombosis has also been reviewed (1).
These recommendations are based on evidence and current Australian dietary intakes.
ëGood evidenceí is defined as demonstration of an association between the exposure variable and clinical
end-points such as MI, death from CHD and stroke. In addition,
the results are consistently reported in different population groups and the effect demonstrated in long-term
studies. The mechanisms explaining the association are
identified and demonstrated.
'Moderate evidenceí is defined as conclusions reached by inference through surrogate measures of CVD or
known risk factors of CVD without strong supporting
mechanistic and laboratory evidence.
'Little evidenceí is defined as inconsistency in research findings. In this classification, the number and type
of studies is not extensive enough to make a more definitive
judgment.
The Heart Foundation acknowledges the limitations of measuring the independent effect of dietary fats on
health outcomes. It should be emphasised that all
recommendations regarding dietary fatty acids must be considered in the context of overall dietary and
lifestyle habits.
The recommendations relate to the general population as well as to high risk individuals.
Recommendations
Saturated fatty acids
There is good evidence that:
an increase in the consumption of saturated fatty acids is associated with an increase in risk of CHD;
replacing a proportion of saturated fatty acids with n-6 polyunsaturated fatty acids to achieve a ratio of
polyunsaturated to saturated fatty acids of greater than one
will reduce the risk of CHD;
compared to carbohydrate, polyunsaturated and mono-unsaturated fatty acids, an increase in the
consumption of saturated fatty acids results in an increase in the
concentration of total and low density lipoprotein cholesterol (LDL-C); and
replacing saturated fatty acids with carbohydrate, polyunsaturated or mono-unsaturated fatty acids
lowers total cholesterol and LDL-C, with a slightly greater effect
with polyunsaturated fatty acids.
There is little evidence that:
an increase in the consumption of saturated fatty acids increases the incidence of stroke; and
an increase in the consumption of saturated fatty acids increases or decreases the susceptibility to
thrombosis and arrhythmia or increases or decreases blood
pressure.
It is recommended that:
saturated fatty acids and trans fatty acids together contribute no more than 8% of total energy intake.
Trans fatty acids
There is good evidence that:
compared to polyunsaturated and mono-unsaturated fatty acids, trans fatty acids increase the
concentration of total cholesterol and LDL-C, and lowers high density
lipoprotein cholesterol (HDL-C).
There is moderate evidence that:
trans fatty acids increase the risk of CHD, particularly at high levels of intake.
It is recommended that:
trans fatty acids and saturated fatty acids together contribute no more than 8% of total energy intake.
n-6 polyunsaturated fatty acids
There is good evidence that:
replacing saturated fatty acids with n-6 polyunsaturated fatty acids reduces the risk of coronary events
and deaths; and
replacing saturated fatty acids with n-6 polyunsaturated fatty acids lowers the concentration of LDL-C,
total cholesterol and plasma triglyceride.
There is little evidence that:
an increase in the consumption of n-6 polyunsaturated fatty acids increases or decreases the
susceptibility to thrombosis and arrhythmia or increases or decreases
blood pressure.
It is recommended that:
n-6 polyunsaturated fatty acids contribute 8 to 10% of total energy intake.
n-3 polyunsaturated fatty acids
There is good evidence that:
marine n-3 polyunsaturated fatty acids reduce coronary heart events;
fish intake reduces the risk of coronary death;
marine n-3 polyunsaturated fatty acids prevent arrhythmia in animals; and
marine n-3 polyunsaturated fatty acids reduce the concentration of plasma triglyceride.
There is moderate evidence that:
marine n-3 polyunsaturated fatty acids prevent arrhythmia in humans; and
-linolenic acid intake reduces the risk of coronary end points.
There is little evidence that:
the anti-thrombotic effect of n-3 polyunsaturated fatty acids has any impact on coronary end points.
It is recommended that:
at least two fish (preferably oily fish) meals per week are consumed;
both plant and marine n-3 polyunsaturated fatty acids are consumed since it is possible that ?-linolenic
acid and marine n-3 polyunsaturated fatty acids protect
against CHD by different mechanisms; and
plant n-3 polyunsaturated fatty acid intakes be at least 2g per day.
Mono-unsaturated fatty acids
There is good evidence that:
replacing saturated fatty acids with mono-unsaturated fatty acids lowers total and LDL-C, although not
to the same extent as polyunsaturated fatty acids.
There is little evidence that:
mono-unsaturated fatty acids have an independent effect on coronary endpoints; and
an increase in the consumption of mono-unsaturated fatty acids increases or decreases the susceptibility
to thrombosis and arrhythmia or increases or decreases
blood pressure.
It is recommended that:
a proportion of dietary saturated fatty acids should be replaced by mono-unsaturated fatty acids as a
strategy for reducing the intake of saturated fatty acids.
Dietary cholesterol
There is moderate evidence that:
dietary cholesterol increases total cholesterol and LDL-C but substantially less so than saturated and
trans fatty acids; and
dietary cholesterol contributes to the development of CHD.
It is recommended that:
people at low coronary risk can reasonably eat moderate quantities of cholesterol-rich foods; and
people with plasma cholesterol levels greater than 5.0mmol/L or with other risk factors should restrict
the intake of cholesterol-rich foods.
Total fat
There is good evidence that:
an increase in the consumption of saturated and trans fatty acids, rather than total fat, increases the risk
of CHD.
It is recommended that:
the emphasis be placed on restricting the combined intake of saturated and trans fatty acids to less than
8% of total energy intake.
The Heart Foundation is undertaking a more detailed review of the dietary factors affecting weight status
before making a specific recommendation on total fat intake.
Reference
1. National Heart Foundation of Australia. A review of the relationship between dietary fat and
cardiovascular disease. Aust J Nutr Diet 1999;56(4 Suppl):S5-S22.
Reprinted with permission from the Dietitian's Association of Australia, from the Australian Journal of
Nutrition and Dietetics 1999;56(4 Suppl):S3-S4.
Nov 99