Coconut oil is not usually recommended in healthy diets because of its high saturated fat content yet the media is awash with reports about the wonderful health benefits of coconut oil. Is this new science or marketing hype?
Among vegetable oils, coconut oil is one of the richest in saturated fat – about 86-87% of all its fatty acids are saturated. Given the latest advice to replace saturated fat with unsaturated fat it would appear that coconut oil is the last vegetable oil a credible nutritionist would recommend. Wouldn’t all that saturated fat just raise blood cholesterol and increase heart disease risk?
The case for coconut oil
Coconut oil advocates argue that not all saturated fat is the same and that the health effects of coconut oil are better than might be expected. It is true that saturated fat is not a single entity – it’s a collection of different saturated fatty acids, each with its own effect on blood lipids. Medium-chain length saturated fatty acids (6-10 carbons) appear to have little effect, whereas the longer-chain saturated fatty acids (12-16 carbons) all raise total blood cholesterol. Stearic acid, which has 18 carbons, is cholesterol neutral but continues to be treated with suspicion (see below).
Canadian professor Tom Wolever has provided a spirited argument for the adoption of glycaemic index as a measure of carbohydrate quality, lining it up against wholegrains. Which approach should be preferred?
Those who have been following the carbohydrate quality debate will enjoy a recent feisty review by Professor Tom Wolever from the University of Toronto published in the European Journal of Clinical Nutrition. Wolever is the co-inventor of the glycaemic index concept and is obviously a little peeved that other measures of carbohydrate quality such as wholegrain have gained acceptance in dietary guidelines whereas GI has not.
Wholegrains versus GI
Here is how Wolever weighs up the relative merits of wholegrains and GI as measures of carbohydrate quality (minimally edited).
At last a trial of monounsaturated-rich Mediterranean diets for the primary prevention of cardiovascular disease has been published and the results are impressive. The missing piece of the puzzle is now in place. Mediterranean-type diets, moderate in total fat but enriched with unsaturated fats, are now the preferred model for healthy diets. But will nutritionists pay any attention or cling to the low fat dogma for a little longer?
Although advice to eat less saturated fat has been a fixture in Dietary Guidelines for three decades, the last four years have seen a spirited debate about what should take its place in healthy diets. As saturated fat is a macronutrient, one can’t just ‘eat less saturated fat’ and maintain energy balance. Saturated fat needs to be replaced by something else, such as carbohydrate or unsaturated fats. Carbohydrate is now considered a poor replacement for saturated fat as these two macronutrients confer the same risk for heart disease. This leaves mono- and polyunsaturated fats as the better options to replace saturated fat, but which of these should be preferred?