One of the most harmful messages that circulates among the public is a fear of fat consumption. However, there is nothing sharply black or white in nutrition. Whether fat is good or bad for us depends on what fat, when and how we use it, as well as something that is still overlooked – the body adaptation.
Eating fat does not make you fat
You do not need to worry about weight gain just because you eat fat. If someone is gaining weight, total fat and carbohydrate consumption (total energy supply) is higher than what the person expends. It is a very simple equation of balancing energy input and output. This might not work only if you have some genetic problem with metabolism, which is a rare condition and does not apply to most of us. You can lose weight being on high fat or on high carbohydrate diet.1 The only problem for a body is when we have HIGH REFINE FAT AND HIGH SUGAR DIET. This is energetic stress for a body and results in metabolic disruption and number of health problems.
How much do we need?
There is no simple answer to this question. You can eat high-fat diet (yes, I did not make a mistake) with more than 30% calories from fat (many cultures have been eating traditionally high-fat diet). Also, you can be on high carbohydrate diet with fat representing 10-20% (also traditional for many cultures). Nothing wrong with either of these options, you can still be healthy!
What fat to use?
You have two options to choose from – the animal fat or vegetable fat (oil). The animal fat is labelled as bad due to the level of saturated fatty acids and cholesterol. On the other hand, vegetable oils are presented as a healthier option. However, this simplistic labelling is misleading and inaccurate. Rather than looking at animal or vegetable fat in general, we should look at individual fatty acids.
Fatty acids are something like little marbles building a neckless – fat, and the magic is in the balance between them and their combinations in foods. 2,3,4 Our body needs both saturated fatty acids and unsaturated fatty acids, and does not need trans-fatty acids.
Unsaturated fatty acids have two important groups -monounsaturated and polyunsaturated (omega 3 and 6). The research indicates that we need the proportion of omega 6 to omega 3 to be around 4:1, ideally 1:1. However, in our society it is around 15:1.5 This is a problem, because if the diet is high in omega 6 fatty acids, it does not prevent but leads to cardiovascular diseases. 5,6 Therefore, labelling vegetable oil and polyunsaturated fatty acids in general as healthier is not correct.
The benefits of polyunsaturated fatty acids lie foremost in high consumption of omega 3 fatty acids because it reduces the inflammation.5,7 We have just begun to understand that the inflammation 8 and production of free radicals 9,10 drive cardiovascular diseases. Furthermore, there is consistent evidence that monounsaturated fatty acids are beneficial for health,5,11 but we cannot say the same about the saturated fatty acids.
Researchers still argue about the effect of saturated fatty acids on cardiovascular diseases. While some studies show a high risk, 12,13 others no link 14,15 or small improvement when saturated fat substitutes unsaturated.16
Let’s look at the fatty acids composition in the most used fats and oils.
As you can see in the table sunflower oil together with corn, pumpkin and sesame oil contain the highest proportion of omega 6. These oils should be consumed with caution, if not balanced with omega 3 fatty acids. Flaxseed oil is a complete winner in omega 3 content. Olive and rapeseed (canola) oil, as well as goose fat are the highest in monounsaturated fatty acids. The highest in saturated fatty acids are coconut oil, butter, ghee and palm oil.
What fatty acids should you eat?
Definitely, we should try to increase omega 3 and reduce omega 6 consumption. But it is difficult to blame one factor (fatty acids) for health problems when we are simultaneously affected by many others. In the end, it all comes down to metabolic adaptations, individual tolerance of fatty acids and other factors that impact on our health. What is probably more important is quality of the fat/oil and how we use it.
We can turn any oil/fat to unhealthy form
Heating fat/oil to a high temperature or hydrogenation process (turning oil to solid form) leads to the production of trans-fatty acids. Trans-fatty acids trigger inflammation and can contribute to various diseases such as cancer, cardiovascular diseases and others. 17-19 We recognise two types of trans-fatty acids. Ruminant trans-fatty acids represent less than 5% in dairy and ruminant meat. Industrial trans-fatty acids represent up to 60% in margarine and other hardened oils.17 While ruminant trans-fatty acids are considered to not cause a significant health risk, the industrial trans-fatty acids are raising the concerns.
Industrial trans-fatty acids
FDA* and WHO* have already acknowledged the risks of the industrial trans-fatty acids. Also, many countries have started to reduce its level in products and use labels on products. However, even here is not everything black and white. The negative effect of trans-fatty acids can mask diet with balanced omega 6 to omega 3 ratio (1:1). 19,20 Also, there are new technologies that have been developed that can replace a traditional process of hydrogenation and limit production of trans fatty acids in margarine. 21
* FDA – Food and Drug Administration *WHO – World Health Organisation
So, when buying fat/oil, look at whether it is unrefined, cold pressed, refined or hydrogenated fat/oil. A stick margarine is generally much higher in trans-fat than tube margarine. Also, watch out for foods that use refined and hydrogenated oils in their products (crisps, biscuits, chocolate…) and the most of all think about how you are going to use the fat/oil that you buy.
Smoking point and why it matters?
Smoking point of animal fat is higher than plant oil. Also, smoking point of refined oil is higher compare to cold press (virgin) oil. The reason for it is a difference in the structure of fatty acids. We know that heating fat/oil to a high temperature changes the structure of fatty acids and produces different nasty substances such as trans fatty acids, aldehydes, acrylamides and free radicals. And the most harmful is to reheat and reuse such oil. 22
How to reduce production of trans-fat and other bad chemicals?
Light cooking and frying
Unrefined cold press fat and extra virgin oils are the best for cold preparation of salads, sauces and dips. However, for a gentle cooking, quick frying (up to 10 min) you can use any fat or oil. The smoking point of virgin and cold press fat/oil usually does not exceed 175°C. A burning point of butter is around 177°C, as well as coconut oil or rapeseed (canola) oil.
Deep frying and baking
When you decide for deep fry and bake, using fat high in monounsaturated fatty acids is recommended such as olive oil or rapeseed (canola) oil. 23 Also, lard, ghee, duck fat is friendlier for baking and deep frying compared to any oil. We just replaced them due to presence of saturated fat and cholesterol. A lard has smoking point of 182°C and ghee 252°C.
Any highly refined oil ‘’vegetable’’ oil (mixture of different oils such as soy, corn and sunflower oils), refined sunflower, or corn oil have high smoking point because they have changed structure of fatty acids, but these oils are already high in trans-fatty acids and on the top of that have a high level of omega 6.
Let’s wrap it up
- You can eat high fat or high carbohydrate diet; the problem is high refined fat and high in sugar diet.
- Watch for the level of omega 6 in oil you use daily and make sure you eat at least 0.65 g/day of omega 3 fatty acids to balance omega 6 to omega 3 ratio. 5
- Olive oil is one of the best option for high level of monounsaturated fatty acids and flaxseed oil for high level of omega 3 fatty acids.
- There is no definite evidence for saturated fat. Moderate consumption of cold press coconut oil, ghee or butter from grass-fed cows is not going to harm your health.
- Industrial trans fatty acids can be harmful to our health and so should be avoided. Try to limit heating fat/oil to high temperature, deep frying and use of highly refined fats and hydrogenated oils and their products.
- For cold recipes and quick frying is suitable any oil. For deep frying and baking, oils high in monounsaturated fat such as olive and canola oil or saturated fat (animal fat, coconut oil) are better option than ‘’vegetable’’ oil, corn or sunflower oil.
- Gardner CD et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion. 2018;319(7):667-679.
- Khaw KT et al. Randomised trial of coconut oil, olive oil or butter on blood lipids and other cardiovascular risk factors in healthy men and women. BMJ Open 2018; 8:e020167.
- Nettleton JA et al. Saturated Fat Consumption and Risk of Coronary Heart Disease and Ischemic Stroke: A Science Update. Ann Nutr Metab. 2017;70(1):26-33.
- Mensink R. P. Effects of products made from a high-palmitic acid, trans-free semiliquid fat or a high-oleic acid, low-trans semiliquid fat on the serum lipoprotein profile and on C-reactive protein concentrations in humans. European Journal of Clinical Nutrition. 2008;62(5):617–624. doi: 10.1038/sj.ejcn.1602756.
- Simopoulus AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother 56, 2002;365–379
- Ramsden CE et al. Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. BMJ. 2013; 346:e8707.
- Calder PC. n-3 polyunsaturated fatty acids, inflammation, and inflammatory diseases. Am J Clin Nutr. 2006; 83:1505S–19S.
- Libby P. Inflammation and cardiovascular disease mechanisms. Am J Clin Nutr 2006; 83(suppl):456S– 60S.
- Lankin VZ et al. Oxidative stress in atherosclerosis and diabetes. Bull Exp Biol Med. 2005; 140:41–3.
- Mylonas C, Kouretas D. Lipid peroxidation and tissue damage. In Vivo. 1999 May-Jun;13(3):295-309.
- Pérez-Jiménez F. Protective effect of dietary monounsaturated fat on arteriosclerosis: beyond cholesterol. Atherosclerosis. 2002 Aug;163(2):385-98.
- Hu FB et al. Dietary saturated fats and their food sources in relation to the risk of coronary heart disease in women. The American journal of clinical nutrition. 1999; 70:1001–1008.
- Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition. 2010; 91:535–546.
- de Souza RJ et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ. 2015;351:h3978.
- Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010; 91:535–546.
- Hooper L, Martin N, Abdelhamid A, Davey Smith G. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews 2015, Issue 6. Art. No.: CD011737.
- Wilczek MM. Trans -Fatty Acids and Cardiovascular Disease: Urgent Need for Legislation. Cardiology 2017;138:254–258.
- Ginter E, Simko V. New data on harmful effects of trans-fatty acids. Bratisl Med J 2016; 117 (5): 251 – 253.
- Takeuchi H, Sugano M. Industrial Trans Fatty Acid and Serum Cholesterol: The Allowable Dietary Level. J Lipids. 2017;2017:9751756.
- Mensink RP. Effects of products made from a high-palmitic acid, trans-free semiliquid fat or a high-oleic acid, low trans semiliquid fat on the serum lipoprotein profile and on C-reactive protein concentrations in humans. European Journal of Clinical Nutrition (2008) 62, 617–624.
- Dijkstra AJ (2006). Revisiting the formation of trans isomers during partial hydrogenation of triacylglycerol oils. Eur J Lipid Sci Technol 108, 249–264.
- Ng C. Heated vegetable oils and cardiovascular disease risk factors. Vascular Pharmacology 61 (2014) 1–9.
- Peng CY et al. Effects of cooking method, cooking oil, and food type on aldehyde emissions in cooking oil fumes. Journal of Hazardous Materials 324 (2017) 160–167.
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