Nutrition
Dietary Fats and Total:HDL Cholesterol Ratios
Risk is reduced most
effectively when tans fatty acids and saturated fatty
acids are replaced with unhydrogenated,
unsaturated fatty acids.
The lower the total:HDL cholesterol ratio the lower the overall risk of coronary heart disease. When individual dietary fats were compared, a high intake of animal or saturated fats such as butter and shortening raised the ratio (indicating increased risk). Solid stick margarine and palm oil also raised the ratio and increased risk.
Surprisingly, when a high intake of carbohydrate was substituted for fat, the overall risk went up as well. A high carbohydrate/low fat diet suppresses HDL cholesterol thus raising overall coronary risk even though total cholesterol levels decrease.
On the other hand, keeping the total fat intake of the diet the same but substituting unsaturated fats saw a decrease in the risk ratio (improved coronary risk). The fats that were best at improving the risk ratio were olive oil, soybean oil, and rapeseed or Canola oil. Notice below that mayonnaise also improved risk even more than soft tub margarine because it has less trans fatty acids. Mayonnaise is primarily a vegetable oil.
Changes in the ratio of total to HDL cholesterol when substituting 10% of
the daily calories with the above fats (or carbohydrate) from the "average
US dietary fat" intake.
This study, including data from 60 dietary trials, gives good evidence that it is the kind of fat that is most important in lowering overall coronary risk. A very low fat diet was not nearly as effective in reducing risk as a diet that had a moderate fat intake but was primarily from unhydrogenated (trans fat free) vegetable oils. This means that for best results in preventing heart disease:
- Eliminate animal fats such as butter, as well as palm oil and other saturated fats as much as possible
- Eliminate all trans fats such as hard stick margarine, shortening, deep fat fried foods, and foods made with these fats (e.g. pastry, chips, and snack foods) as much as possible
- In their place choose healthy fats such as unhydrogenated vegetable oils (e.g. olive, soybean, and Canola), trans fat free margarines, and fats found naturally in plant foods such as nuts, avocado, flax meal, seeds, and olives.
- Avoid a very low fat/high carbohydrate diet. While this type of diet was promoted by some people in past years as the best, new data shows that eliminating all "bad fats" and choosing "healthy fats" in moderate amounts is more effective.
The researchers make these conclusions:
- Our results emphasize the risk of relying on cholesterol alone as a marker for coronary artery disease.
- Replacement of saturate fats with cis (unhydrogenated) unsaturated fats reduces coronary heart disease.
- In this analysis, replacement of trans fatty acids with unsaturated fatty acids from unhydrogenated oils is the single most effective measure for improving blood lipid profiles.
- The effect of low fat/high carbohydrates on total:HDL cholesterol levels justifies caution in recommending high carbohydrate diets for the prevention of coronary heart disease [because they usually lower HDL cholesterol].
References
Mensink RP et al. Effects of dietary fatty acids and
carbohydrates on the ratio of serum total to HDL cholesterol and on serum
lipids: a meta analysis of 60 controlled trials, American Journal of
Clinical Nutrition, May 2003; 77:1146-55
Making Healthy Choices articles are written
by Don Hall, DrPH, CHES president of LifeLong
Health with contributions from associated health professionals.
Content is general health information from evidence based research. It's
purpose is not to treat disease or take the place of advice by your doctor
but to promote healthy lifestyles. Persons with health problems should
contact their physician for specific guidance.
Copyrighted 2003 by PrevMedix LLC. All rights reserved. Do not make unauthorized copies.
Updated: 7-14-03 DRH