Good or Bad for Your Health?
Introduction
Saturated fats split opinion. They are a topic of heated debate in the health and nutrition space. For decades, they were demonised as a major culprit for heart disease and chronic health conditions. Nowadays, you’ll see influencers and scientists boasting the potential benefits of saturated fats on their social media pages. As the consumer of the conflicting information, this leaves you confused and apprehensive. It poses the questions:
“Should I be eating red meat and dairy?”
“…Or just lean poultry and low-fat alternatives?”
“Can I cook with butter?”
“What even are saturated fats?”
If some of these questions sound familiar or your interest has been spiked, then this is the article for you. This piece aims to uncover the truth based on the most contemporary scientific literature. It is designed to arm you with the knowledge required to navigate the confusion and the apprehension. The complexities are to be unravelled and within that the empowerment to make healthful decisions when it comes to your dietary choices.
What is Saturated Fat?
As mentioned, the topic of saturated fats is the source of some controversy. The general mainstream consensus points to an increased risk of heart disease from regular consumption of saturated fats. You’ll even see this reflected in national guidelines. 1 In most cases, this has become the accepted perspective. However, in accepting this notion, we turn a blind eye to the contemporary evidence that is consistently emerging. This new science presents evidence to the contrary and challenges the existing dogma around saturated fats.
Saturated fats are a form of dietary fats that contain fatty acids with no double bonds between their carbon atoms. This is where the ‘saturated’ comes from, as the carbon chain of fatty acids is fully saturated with hydrogen atoms. It is this structure that makes saturated fats solid at room temperature.
Contrary to popular belief, these hydrogen-soaked fats can be derived from both animal and plant sources:
Animal Sources: red meat (e.g., beef and pork), poultry skin, butter, full-fat dairy (e.g., cheese, cream and whole milk).
Plant Sources: coconut oil, palm oil and cocoa butter.
Saturated fats come in different shapes and sizes, too. Short-, medium--, long---, and very-long-chain fatty acid structures exist (dictated by the number of carbons in its chain/tail), with each exerting a different function. In fact, saturated fatty acids in the same classification can exert different functions. For example, palmitic acid and stearic acid are both long-chain saturated fats (derived from many food sources) and yet the former has a greater effect on blood cholesterol levels than the latter. 2 These variations exemplify the complexities of saturated fats and emphasise the potential limitations that come with discussing them in general.
With an enhanced understanding of exactly what saturated fats are and an insight into the nuances that make a holistic extrapolation unwarranted, it is now necessary to delve deeper into the source of the contradictions. How does the historical perspective differ from the conventional view? And what is the reason for the confusion and misnomers? All will be answered in the text to follow.
Saturated Fats and Health: The Historical Perspective
A very brief history lesson is required to uncover the origin of the claims concerning the ‘health detriments’ of saturated fats and why they persist to this day. A chap named Dr Ancel Keys conducted some seminal research in the mid-to-late 1900s to propose an association between our diet and the development of heart disease. 3 The diet-heart hypothesis was proposed, and the notion that saturated fats raise blood cholesterol levels and thus the risk of heart disease was born.
Since its inception, Keys’ suggestion has been widely accepted in academic and nutrition communities across the globe and remains a major influence on official nutrition guidelines today. However, emerging research and a closer look at some flaws in Keys’ work has presented an alternative perspective.
Saturated Fat and Heart Disease
With much of the concern around saturated fat related to its effects on heart disease, it is necessary to take a closer look at this mechanism. Heart disease is most commonly the result of atherosclerosis, which is the build-up of plaque in our arteries. To appreciate the mechanism, some knowledge of the formation of arterial plaque is required.
Our arteries are lined with a fine layer of cells known as the endothelium. The endothelium acts as a selectively permeable barrier between our blood and the rest of our body. One of the nutrients capable of passing through this barrier is the famed low-density lipoprotein (LDL), whose primary objective is to transport cholesterol around the body. Plaque formation occurs when LDL particles are retained in the space beneath the endothelium (named the intima), where they become susceptible to oxidation. Once the process ensues, the immune system recognises the oxidising LDL as a danger and attacks white blood cells (named macrophages) to consume the LDL particles. This response proves incredibly inflammatory and results in the formation of foam cells (from the macrophages), which are incapable of proper function and begin to accumulate into the fatty build-up that we call plaque.
Pause.
Breathe.
The work of Keys and colleagues identified saturated fats as a potential contributor to raised blood cholesterol levels. Hence, the reason that dietary saturated fat consumption took the brunt of the blame for heart disease. However, some more contemporary, seminal research has contradicted these claims…
Saturated Fats and Health: The Contemporary View
…A recent systematic review and meta-analysis (study of studies) analysed the effects of saturated fats on our blood lipids (fats). The World Health Organisation (WHO) went on to publish the study in 2016 4, and the results demonstrate inconsistencies that challenge the claims of Keys. A superficial look at the analysis would suggest that saturated fats raise blood lipid levels (and thus LDL), when compared to carbohydrates and unsaturated fats, and thus increase the risk of heart disease and inflammation. However, a deeper look at the data shows that despite this increased risk, there is no direct link between saturated fat intake and heart disease. In other words, the isolated consumption of saturated fat may increase your risk of developing heart disease, but it does not mean that you will develop heart disease.
The PURE study (2023) supports the suggestion that saturated fat intake is not necessarily a direct determinant of heart disease. 5 This research, conducted on 245,000 individuals across 80 countries, showed that the less saturated fats (and cholesterol) one consumed, the lower their health score, and vice versa.
Isolated evidence from specific studies further demonstrates the complexity of saturated and their different structures. Whole-fat dairy (~70% saturated fat) is often a victim of villainisation. Studies comparing sources of dairy-derived saturated fats show that whilst butter increases LDL cholesterol, cheese may not. 6 This takes us back to the start of this article, re-emphasising the various lengths of saturated fatty acid chains and how their matrices (structure) can influence their metabolic effects.
The key takeaway from all of this emerging evidence is that our diet needs to be considered as a whole. Singling out foods and nutrients for their associative links with disease does not achieve anything, especially when there is no concrete evidence to imply direct causation. A holistic view of one’s overall diet and lifestyle is a far better indicator of health and wellness.
The Round-Up
All the time a lack of clarity persists around dietary fat consumption, from all sources, I personally deem it erroneous to demonise saturates. The evidence indicates that when compared to monounsaturated and polyunsaturated fat, saturated fat does increase several risk factors pertaining to heart disease. However, to take that statement in isolation undermines the entire diet, and with recent research suggesting that the adverse effects of saturated fat are far more moderate than previously deemed, it is necessary to reconsider old dogma.
Association is not the same as causation, and isolation of a single nutrient is not representative of the broader diet. To reuse the full-fat dairy example, which is rich in saturated fats, we can uncover a plethora of confounders that offset a lot of the associated negative effects. Dairy also contains beneficial nutrients like high-quality protein and numerous vitamins and minerals, which are conducive to health. The same can be said for unprocessed red meat (not the same as processed red meat).
In conclusion, a nutrient-dense, diverse diet consisting primarily of whole foods from a range of sources should form the basis of our approach. This aligns with the reduction of highly processed foods, including overconsumption of refined sugars. Aim for a higher intake of fruits, vegetables, nuts, legumes, and poultry, and moderate your intake of fish, whole-fat dairy and red meat, but do not eliminate or vilify it. In combination with other lifestyle factors (e.g., exercise, sleep and stress management), this approach offers one the power to unlock their best self and protect against disease.
References
1. Facts about fat (2022) nhs.uk. Available at: https://www.nhs.uk/live-well/eat-well/food-types/different-fats-nutrition/ (Accessed: 14 October 2024).
2. Grundy, S.M. (1994) ‘Influence of stearic acid on cholesterol metabolism relative to other long-chain fatty acids’, The American Journal of Clinical Nutrition, 60(6 Suppl), pp. 986S-990S. Available at: https://doi.org/10.1093/ajcn/60.6.986S.
3. Oransky, I. (2004) ‘Ancel keys’, The Lancet, 364(9452), p. 2174. Available at: https://doi.org/10.1016/S0140-6736(04)17578-8
4. Mensink, R.P. and Organization, W.H. (2016) Effects of saturated fatty acids on serum lipids and lipoproteins: a systematic review and regression analysis. World Health Organization. Available at: https://iris.who.int/handle/10665/246104 (Accessed: 14 October 2024).
5. Mente, A., Dehghan, M., Rangarajan, S., O’Donnell, M., Hu, W., Dagenais, G., Wielgosz, A., A. Lear, S., Wei, L., Diaz, R. and Avezum, A. (2023) ‘Diet, cardiovascular disease, and mortality in 80 countries.’, European Heart Journal, 44(28), pp.2560-2579.
6. Pj, H. and Km, P. (2012) ‘Influence of dairy product and milk fat consumption on cardiovascular disease risk: a review of the evidence’, Advances in nutrition (Bethesda, Md.), 3(3). Available at: https://doi.org/10.3945/an.112.002030.
