Healthy fat in avocados

Low-fat food on supermarket shelves (photo: Barry Ennor)

Low-fat food on supermarket shelves (Photo: Barry Ennor)

Look, I am the first to admit that I am getting a little confused here. It used to be simple. Fat was bad and should be avoided. It clogged your arteries, increased your LDL (or bad) cholesterol, and led to cardiovascular disaster. Saturated fats, specifically, have been targeted as being especially detrimental to good health. Low-fat products appeared on the shelves and are now abundant in every supermarket. The World Health Organization recommended that fat should constitute no more than 30% of our energy intake, and to restrict the intake of saturated fatty acids to less than 10% of daily energy intake. Given that fat provides about double the energy on a weight basis compared to other macro nutrients, products with more than 15g of fat per 100g should be avoided (alright, a bit oversimplified, if you have your calculator with you in the supermarket you can calculate the average fat content across the foods in your trolley and, given that you know your consumption amounts of each, you can get your daily fat consumption right – good luck with that).

Fat the good guy?

Now fat is suddenly the good guy and carbohydrates should be avoided. My fellow blogger at Tuit Nutrition, citing published research, says:

  • that there is a lack of any clear evidence that saturated fats are promoting any of the conditions that can be attributed to polyunsaturated fatty acids making one wonder how saturated fats got such a bad reputation in the health literature;
  • that the influence of dietary fats on serum cholesterol has been overstated, and a physiological mechanism for saturated fats causing heart disease is still missing;
  • that there is no reason to believe that replacing fat in the diet with carbohydrate at a constant caloric intake will improve the serum lipid profile significantly;
  • that indeed, a low-fat, high-carbohydrate diet causes an increase in serum triglycerides and small, dense LDL particles, which are more strongly associated with coronary artery disease than serum total cholesterol or the amount of actual LDL cholesterol bound to particles;
  • and that replacement of saturated fat with a higher carbohydrate intake, particularly refined carbohydrate, can exacerbate the atherogenic dyslipidemia associated with insulin resistance and obesity that includes increased triglycerides and small LDL particles, as well as reduced HDL cholesterol.

Translated, the now espoused view says that saturated fat might not be that dangerous after all and when we cut back on saturated fat and eat more carbohydrates instead, as we have been told to do for some fifty years, markers for heart disease get worse. That is really turning everything on its head.

Healthy fat in avocados

An avocado a day to protect the heart (Photo: Olle Svensson)

An avocado a day to protect the heart (Photo: Olle Svensson)

So how do I now justify writing this blog on the beneficial effects of unsaturated fatty acids from avocados replacing some saturated fat in the diet? You have to be the judge of that.

Anyway, according to new research published in the Journal of the American Heart Association, eating one avocado a day as part of a heart healthy, cholesterol-lowering moderate-fat diet can help reduce LDL cholesterol levels in overweight and obese individuals. The researchers evaluated the effect of avocados on cardiovascular risk factors by replacing saturated fatty acids from an average American diet with unsaturated fatty acids from avocados. Some 45 healthy, overweight or obese patients between the ages of 21 and 70 were put on three different cholesterol-lowering diets. They consumed an average American diet (consisting of 34 percent of calories from fat, 51 percent carbohydrates, and 16 percent protein) for two weeks prior to being randomly sequenced between each of three test diets for five weeks comprising a lower fat diet without avocado, a moderate-fat diet without avocado, and a moderate-fat diet with one avocado per day.

The lower fat diet, that provided 24% of calories as fat (11% from monounsaturated fatty acids), lowered the LDL cholesterol by 7.4 mg/dL, while the two moderate fat diets that both provided 34% of calories as fat (17% of calories from monounsaturated fatty acids) lowered the LDL cholesterol by 8.3 mg/dL (no avocado) and 13.5 mg/dL (with avocado), respectively. Several additional blood measurements were also more favourable after the avocado diet versus the other two cholesterol-lowering diets including total cholesterol, triglycerides, small dense LDL, non-HDL cholesterol, and others.

The researchers claimed that the results demonstrate that avocados have beneficial effects on cardio‐metabolic risk factors that extend beyond their heart‐healthy fatty acid profile that could be due to other micronutrients and bioactive components in avocados that may play an important role in reducing the risk of heart disease.

What to eat

So should you now start eating an avocado a day? And add to that a cup of blueberries a day as I will point out in a future blog, and on top of that increase your intake of wholegrain foods that will also be covered in a future blog? Your call, I am only providing the facts.

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