Fatty Acids in Health and Disease
Katherine Wohl, RDN, LD, IFNCP, CLC
John Bagnulo, MPH, PhD
Fats are an essential part of any diet. From the absorption of fat-soluble vitamins and maintaining blood sugar balance to their role in brain health, immune function, mitochondrial health – their importance as a foundational aspect of one’s diet cannot be emphasized enough. There is a growing body of evidence that supports not only its inclusion, but that they may be required for optimal health. Still, with a long history of being vilified in public health messaging, the important role they play is often misunderstood or poorly accepted within the broader community.
There are several types of fatty acids, classified by the number of double bonds in the carbon chain and where they occur.
- Saturated fat: no double bonds
- Coconut, dairy, meat, macadamia nuts, palm oil
- Sub classes: SCFAs and MCFAs
- Monounsaturated fat: one double bond
- Olives, almonds, avocados, macadamia nuts, hazelnuts
- Polyunsaturated fat: multiple double bonds
- Omega-3 fatty acids: first double bond on the 3rd carbon
- Flax seeds, sardines, mackerel, anchovies, salmon, tuna
- Omega-3 fatty acids: first double bond on the 3rd carbon
- Omega-6 fatty acids: first double bond on the 6th carbon
- Sunflower, safflower, soybean, canola, corn, and vegetable oil blends
Understanding this structuring is critical because it helps determine the physiologic compatibility of each fatty acid and the balance required among them for optimal health. This is often overlooked, however, since the assessment of dietary fat has been solely focused on its influence on serum cholesterol and lipid levels.
Far more important is its role in numerous cellular processes and cellular health. For example, the fatty acids that are predominant in our diet influence the health of a cell’s phospholipid bilayer and mitochondria, which in turn impact our health. Saturated fat, because of its rigid structure, creates a more stable, tightly packed phospholipid bilayer that allows it to be resistant to free radicals and oxidative stress (1). Similarly, it supports cardiolipin remodeling within the mitochondria, allowing it to function optimally and keep producing energy effectively (2). In contrast, predominant polyunsaturated fat in the diet can create an unstable phospholipid bilayer and lead to free radical damage and oxidative stress in the mitochondria, promoting inflammation in the body (1-3).
Balance is also key to understanding the health impact of dietary fat, especially polyunsaturated fat. While we know omega-6 and omega-3 fatty acids are considered essential by the body, it is estimated that the current ratio of omega 6:omega 3 in the US is 30:1. A ratio of 3:1 is suggested to prevent inflammation and is closer to what our ancestors ate. This imbalance is an enormous contributor to the high level of inflammation that plays a role is so many chronic diseases that we see today. It is largely due to the excess consumption of industrial seed oils that dominate our food supply because they are cheap to produce and become the base of so many packaged and processed foods.(4-7)
While these core concepts emphasize the importance of saturated fat, highlighting this can still seem alarming given 50 years of being told that consuming saturated fat is dangerous to health, especially with regard to heart disease. Yet what has been brought to light over the past several years is that the science on which this messaging was built, initially by Ancel Keys and the Seven Countries Study published in 1952, was weak at best – built on poorly designed and poorly interpreted clinical trials.
There have been several studies which have debunked this myth (see the references below) and showed that eating fat, especially when in place of refined carbohydrates and sugar, is protective and often demonstrates risk reduction. (8-12) Notably, the PURE Study, an epidemiological study published in 2017 that included 18 countries and over 50,000 subjects, showed lower all-cause mortality with higher levels of dietary fat, among other findings (13) . WHO and CDC data have also showed no association between total serum cholesterol and all-cause mortality or mortality from cardiovascular disease.
Understanding the science can help us embrace a new way of looking at and consuming fat. So what can we do to ensure that we are using fat to our advantage in optimizing our health?
- Make saturated and/or monounsaturated fats the foundation of fatty acid composition and leading sources of calories.
- Remember to source high quality versions for the most benefit
- Use saturated and monounsaturated fats as the predominant cooking oils as their inherent smoke points are generally higher and are less susceptible to oxidation.
- High heat cooking: coconut oil, grass fed butter, ghee, avocado oil
- Low/medium heat or dressing/finishing: olive (350 degrees and below), flax oil (no heat)
- Consume at least 1000mg of omega 3 fatty acids daily.
- Emphasize small, oily fish like salmon, mackerel, sardines
- Choose grass fed meat for higher levels
- Limit the use of and/or consumption of omega 6 dominant seed oils as these rapidly produce physiological imbalances of omega 6 to omega 3 fatty acids.
- Industrial seed oils: corn, soybean, sunflower, safflower, canola, vegetable oil blends
- Read labels closely to identify these oils in processed and packaged foods, beverages, and enteral formulas.
- Aim for dietary omega 6 to omega 3 ratios of 3:1 for young children, 2:1 or less for adults, 1:1 for higher levels of inflammation.
- With signs of chronic inflammation (elevated CRP) consider omega index-type or RBC membrane testing to assess omega 6 to omega 3 fatty acid imbalances.
We hope this clears some confusion and makes you more confident to include fat!
- Marcus K. Dymond. Mammalian phospholipid homeostasis: evidence that membrane curvature elastic stress drives homeoviscous adaptation in vivo. J. R. Soc. Interface 2016 13 20160228; DOI: 10.1098/rsif.2016.0228. Published 17 August 2016
- Ting, H., Chen, L., Chen, J. et al. Double bonds of unsaturated fatty acids differentially regulate mitochondrial cardiolipin remodeling. Lipids Health Dis 18, 53 (2019).
- Lu YW and Claypool SM. Disorders of phospholipid metabolism: an emerging class of mitochondrial disease due to defects in nuclear genes. Frontiers in Genetics. 03 February 2015.
- Guyenet SJ, Carlson SE. Increase in adipose tissue linoleic acid of US adults in the last half century. Adv Nutr. 2015;6(6):660-664. Published 2015 Nov 13. doi:10.3945/an.115.009944
- Tobias Pischon. Circulation. Habitual Dietary Intake of n-3 and n-6 Fatty Acids in Relation to Inflammatory Markers Among US Men and Women, Volume: 108, Issue: 2, Pages: 155-160, DOI: (10.1161/01.CIR.0000079224.46084.C2)
- Taha, A.Y. Linoleic acid–good or bad for the brain?. npj Sci Food 4, 1 (2020). https://doi.org/10.1038/s41538-019-0061-9
- Gray, B., Steyn, F., Davies, P. et al. Omega-3 fatty acids: a review of the effects on adiponectin and leptin and potential implications for obesity management. Eur J Clin Nutr 67, 1234–1242 (2013).
- Bonthuis M, Hughes MC, Ibiebele TI, Green AC, van der Pols JC. Dairy consumption and patterns of mortality of Australian adults. Eur J Clin Nutr. 2010;64(6):569-577. doi:10.1038/ejcn.2010.45
- Ravnskov U, Diamond DM, Hama R, et al. Lack of an association or an inverse association between low-density-lipoprotein cholesterol and mortality in the elderly: a systematic review. BMJ Open. 2016;6(6):e010401.
- Yousufuddin M, Takahashi PY, Major B, et al. Association between hyperlipidemia and mortality after incident acute myocardial infarction or acute decompensated heart failure: a propensity score matched cohort study and a meta-analysis. BMJ Open 2019;9(12):e028638. https://doi.org/10.1136/bmjopen-2018-028638
- Ho Frederick K, Gray Stuart R, Welsh Paul, Petermann-Rocha Fanny, Foster Hamish, Waddell Heather et al. Associations of fat and carbohydrate intake with cardiovascular disease and mortality: prospective cohort study of UK Biobank participants BMJ 2020; 368 :m688
- Hamley, S. The effect of replacing saturated fat with mostly n-6 polyunsaturated fat on coronary heart disease: a meta-analysis of randomised controlled trials. Nutr J 16, 30 (2017).
- Dehghan M, Mente A, Zhang X et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Lancet. 2017; 390: 2050-2062