Saturated or not? The debate about fat carries on
Posted on : 12/7/2016
Lately there have been many claims that saturated fats should regain their prominence on our plates. There is, however, still a lot of controversy about the role of saturated fat in our diet.
Throw the word “fats” into casual conversation and there will most likely be a debate on the latest diets and nutrition trends.
'Butter is back'
Headlines over the past few years have claimed that saturated fats should feature more prominently on our plates. This indicates that the truth probably lies somewhere between the low-fat era of the 90s and the present day chant of “butter is back”.
There is however still a lot of controversy about the role of saturated fat in the diet, causing much confusion as to the actual truth about fats.
Facts on saturated fats
Fat is one of the three macronutrients important for a healthy and balanced diet, along with carbohydrates and protein. Fats play a role in many structural and metabolic functions in the body: providing fat-soluble vitamins A, D, E and K, protecting the heart, keeping the immune system strong and providing essential fatty acids for brain development. However, the type of fat we chose is of great importance.
A fat molecule is made up of varying lengths of carbon and hydrogen atoms. The more hydrogen in a fat molecule, the more saturated the fat is. Fats containing a large amount of saturated fatty acids include foods such as butter, cream, bacon, chicken skin, fatty cuts of meat, palm oil and coconut oil.
Fats high in monounsaturated fatty acids are avocado, olives, nuts, olive oil, and foods high in polyunsaturated fats are peanuts, walnuts, oily fish like salmon that contain essential omega-3 fatty acids.
The facts remain
Strong evidence shows a direct relationship between high saturated fat diets and raised LDL, the bad type of cholesterol. As a result, recommendations are that saturated fats should be limited in the diet to less than 10% of total dietary energy per day.
This advice remains, despite some studies reigniting the debate. The supposed controversial findings of these studies arose simply because of the poor quality of the studies, with methodological problems and small sample sizes, and not because previous research previously done is inaccurate.
For example, one recent study showed a 17% reduction in cardiovascular events in people who followed diets lower in saturated fats. In another study, one of the largest and longest studies on over 120 000 participants followed for 24 years, results showed that replacing saturated fats with the same amount of monounsaturated and polyunsaturated fats lowered the risk of coronary heart disease by a considerable 15 and 25%, respectively.
We know that unsaturated fats in the diet yield health benefits, as confirmed by studies on the Mediterranean diet. As there is strong evidence that supports replacing saturated fat with unsaturated fat in the diet, why on earth would we be adding large amounts of saturated fat into our diet?
Not all saturated fats are equal
Not all saturated fats are created equal when it comes to health. Fats are categorised by the length of the fatty acid chain: the more carbon atoms in the fat molecule, the longer the chain length. The most common saturated fats are lauric acid (12 carbons), myristic acid (14 carbons), palmitic acid (16 carbons) and stearic acid (18 carbons).
Because of the longer length of the saturated fat molecule, this type of fat has the ability to tightly pack into membranes of our cells and this can cause adverse health benefits. Therefore, we cannot consider all saturated fats as equal. Some saturated fats are convincingly more harmful to our health than others.
Stearic acid, for example, has a neutral effect on bad LDL cholesterol levels, while the jury is still out on lauric acid, the main fat in coconut oil. Convincing research shows that palmitic acid and myristic acid, however, cause inflammation, damaging cell walls and contributing to hardening of the arteries.
While some saturated fatty acids may well have a neutral effect on our health, this does not necessarily mean that all saturated fats should be exonerated and used in large amounts.
The South African Food-based Dietary guidelines recommend that South Africans should replace some animal and plant sources of saturated fats. These recommendations are supported by other international bodies such as the American Heart Association and the European Society of Cardiology.
If we laid out all the fats we ate during the course of a week, we should see mainly monounsaturated fats such as found in nuts, avocado pear, olive oil, canola oil, olives and low-salt, sugar-free nut butters. Polyunsaturated fats that contain omega-3 fatty acids should make up 6-10% of our total fat intake. About 270g of sardines, salmon, pilchards, mackerel or trout per week is enough to provide us with adequate amounts of omega-3.
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2. Hruby A, Hu F. Saturated fat and heart disease: The latest evidence. Lipid Technology. 2016, Vol. 28, No. 1.
3. Li et al. Saturated Fats Compared With Unsaturated Fats and Sources of Carbohydrates in Relation to Risk of Coronary Heart Disease: A Prospective Cohort Study. J Am Coll Cardiol 2015;66:1538–48.
4. Position of the Academy of Nutrition and Dietetics: Dietary Fatty Acids for Healthy Adults. J Acad Nutr Diet. 2014;114:136-153.
5. Smuts CM and Wolmarans P. The importance of the quality or type of fat in the diet: a food-based dietary guideline for South Africa. S Afr J Clin Nutr 2013;26(3)(Supplement):S87-S99.
6. U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015–2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Available at http://health.gov/dietaryguidelines/2015/guidelines/.
Claire Julsing Strydom
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