Due to studies first undertaken in the 1950s, it has been generally accepted that consuming saturated fats and dietary cholesterol will lead to increased serum cholesterol, which will then promote arterial plaque buildup, putting us at risk for heart attacks and strokes. These early studies were joined by others that found an association between saturated fat and heart disease risk, and thus was born the “diet-heart hypothesis,” which equated this association with causation. Dietary recommendations for replacing saturated fats in the diet with vegetable oils and carbohydrates soon followed and continue to this day. Current recommendations by the World Health Organization and by the U.S. Dietary Guidelines are for saturated fat intake to be limited to no more than 10% of daily calories; the American Heart Association would like to see no more than 7%1. The diet-heart hypothesis spawned the low-fat, low-cholesterol food revolution, with an upsurge in the manufacture and sales of packaged foods, polyunsaturated vegetable oils, and refined carbohydrates, accompanied by the development and widespread usage of the cholesterol-lowering statin drugs.
Unfortunately, what has been lost in the furor to lower the world’s cholesterol levels through reduction of saturated fat intake is that the majority of independent research undertaken in this area demonstrates little to no association of saturated fat to heart disease. And when saturated fat does increase cholesterol levels, it often does so in ways that are heart protective.
Confusion from Studies
Early research into the health effects of dietary saturated fats lumped natural saturated fats in with industrial trans fats – “partially hydrogenated oil” on food labels. Since there is no known safe level of ingestion of these man-made solid fats, negative results are no surprise. Our bodies have no use for them, but they take up residence on parts of our cells meant for other fats that our bodies really need.
Secondly, different health effects occur depending on which specific saturated fatty acid is consumed or what type of food is replacing the fat. In the same way that omega-3 polyunsaturated fatty acids produce different effects in our bodies than the omega-6s, saturated fatty acids are also diverse, producing specific metabolic effects, some of which will be discussed, below.
But foods contain more than just fat, and other constituents within a saturated fat-containing meal may influence heart disease risk. Dietary replacements for saturated fats have typically been refined carbohydrates and poly- or monounsaturated vegetable oils, so by comparing the effects of each of these on heart disease risk to those of saturated fats, we can tease out specific heart-friendly compounds.
Saturated Fat Replacements
What we’ve most recently learned is that starchy carbohydrates create far higher cardiovascular disease risk than do saturated fats. This has been suspected for a long time, but a couple of Harvard researchers in 2010 did an extensive review of well-designed studies and concluded that the ratio of total cholesterol to HDL (TC:HDL-C), a good predictor of clinical heart disease endpoints, was much improved by several saturated fatty acids, compared to carbohydrate replacement foods1. It’s also now well known that a diet high in refined carbohydrates is the primary driver of insulin resistance and type 2 diabetes, and these account for a large percentage of the factors that lead to cardiovascular disease.
What about the replacement oils? As for the omega-6 vegetable oils, always a key component of worldwide heart-healthy diet recommendations, it appears that they’re not as healthful as we’ve been led to believe. The Sydney Diet Heart Study, conducted from 1966 to 1973, followed 458 middle-aged men who had had a recent coronary event, i.e., high-risk individuals, to see how they fared on either a diet rich in saturated fats or one that included safflower oil and a low-trans fat safflower margarine, safflower being almost entirely composed of omega-6 fats. After controlling for smoking, age, and other factors, the researchers were completely mystified as to why those consuming the unsaturated fats experienced greater overall mortality than those consuming the saturated fats. A recent re-evaluation of the study plugged in some missing data, allowing a determination of other health effects. This updated analysis demonstrated increased “rates of death from all causes, coronary heart disease, and cardiovascular disease” in the group consuming the vegetable oils2. The authors suggest that the mechanism of action was enhanced oxidation of the oils, the deleterious effect being most pronounced in smokers and high consumers of alcohol, whose oxidative stress is already increased.
Of course, we need to discuss olive oil, too, which has been found in many studies to exert beneficial effects on heart health. These effects are supposedly due to its much-touted monounsaturated fatty acid (MUFA) content, but the latest studies show something else entirely: that it is only virgin and extra virgin olive oil that exert cardiovascular benefits. Why? Mostly likely this is due to their high polyphenol content, the antioxidant compounds that give olive oil its rich gold and green hues. One study found virgin olive oil to exert a profound anti-inflammatory effect, especially when used in conjunction with high vegetable intake3, increasing total antioxidant capacity in study participants more than five times that of the control group4. Olive oil has been shown to be most beneficial in those who have never smoked, are low-to-non alcohol drinkers, and who consume it in its extra virgin state5, where the polyphenol content is highest. The information available from studies is currently insufficient to recommend MUFAs, in general, as more beneficial than other fats6, leading to the conclusion that it most likely is indeed the antioxidant plant compounds.
In conclusion, in well-designed research studies, saturated fats have never been shown to cause heart disease. They have most likely been implicated as a factor due to early measurement limitations, incorrect interpretation of research, and due to being thrown into the ring with trans fats. There is also the issue of food industry agendas, since vegetable oils are often made from soy and corn manufactured by highly subsidized and politically powerful corporations, who want their products promoted. Long-cherished ideas die hard, but you can expect to see natural saturated fats exonerated in the media little by little as time goes on.
Health Effects of Saturated Fats
Saturated fats are composed of fatty acids whose carbon chains naturally contain a full complement of hydrogen atoms, making them solid at room temperature. They are found in animal foods (meats, milk, eggs, butter) and tropical plants (coconut and palm). Manmade trans fats, on the other hand, are highly processed vegetable oils that have been injected with hydrogen atoms, which saturate the carbon chains, straightening out the molecule, and making it solid at room temperature. Manmade trans fats are metabolic poison, with no known safe level of intake.
Not only do we obtain saturated fats from the diet, but our bodies also produce them, a strong indication that they are vital for health. There is an important quote from the study authors of the long-running Framingham Study that has been following thousands of people and their offspring in this Massachusetts community since 1948. This finding, though critically important, has generally been ignored by the medical and pharmaceutical communities7:
…the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower the person’s serum cholesterol.
As with the unsaturated fats, there is no single saturated fat but rather a collection of different saturated fatty acids, each with distinct biological functions.
- Cell membranes: must be 50% saturated fat to ensure waterproofness and optimal function
- Palmitic and stearic acids (long-chain saturated fats) preferred for energy production
- Caprylic and capric acids lower cholesterol8
- Some long-chain fats shown to raise LDL but also to improve important heart disease risk factors: fewer oxidized LDL particles (these lead to plaque formation), higher HDL, lower triglycerides9
- Coconut oil (>90% saturated fat), as compared to soybean oil: improved LDL:HDL ratios and reduced waist circumference in obese women10
- Bones: require saturated fats to properly assimilate calcium
- Liver: saturated fats help protect from alcohol and drug damage
- Lungs: contain palmitic acid, which helps prevent asthma
- Hormones: saturated fats — signaling molecules for hormone production
- Immune system :
- Inhibition of tumor proliferation and induction of apoptosis (programmed cell death)8
- Medium-chain saturated fats (lauric acid in coconut oil and myristic acid in butter) kill bacteria and yeast (Candida) in gut
- Best fats for signaling satiety, the feeling that you’re full and don’t need more food
- Medium-chain saturated fats shown to lead to reduced fat deposition11
- Lower triglycerides and promote weight loss when combined with low carbohydrate intake; can increase triglycerides and body weight when part of high starchy carbohydrate diet9
- Essential nutrients:
- Vitamins A, D, and K2 primarily found in saturated fat-rich animal products such as eggs, butter, and organ meats; absent from most plant foods. Essential for heart health, bone strength, immune function.
Remember, natural saturated fats have been a component of human diets for millennia, long before heart disease rose to prominence as the number one cause of death in our country. Contrary to what we’ve been hearing for decades, saturated fats, as part of a nutritious whole foods diet, can be a vital element for heart health. Sourcing these, and all fats properly, from pastured or at least organically raised animals and organically grown plant foods, will help ensure peak nutrient composition. So take heart, healthy bodies result from eating all types of natural traditionally consumed foods, including saturated fats. Enjoy them in moderation and experience their delicious benefits.
- Misha, R. & Mozaffarian, D. (2010). Saturated fat and cardiometabolic risk factors, coronary heart disease, stroke, and diabetes: A fresh look at the evidence [PDF]. Lipids, 45: 893–905. doi: 10.1007/s11745-010-3393-4
- Ramsden, C.E., Zamora, D., Leelarthaepin, B., Majchrzak-Hong, S.F., Faurot, K.R., Suchindran, C.M.,…Hibbeln, J.R. (2013, Feb 5). 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 [PDF]. BMJ, 346: e8707. doi: 10.1136/bmj.e8707
- Urpi,Sarda, M., Casas, R., Chiva,-Blanch, G., Romero-Mamani, E.S., Valderas-Martinez, P., Arranz, S., …Estruch, R. (2012, Jun).Virgin olive oil and nuts as key foods of the Mediterranean diet effects on inflammatory biomakers related to atherosclerosis [Abstract]. Pharmacol Res, 65(6):577-83. doi: 10.1016/j.phrs.2012.03.006.
- Zamora-Ros, R., Serafini, M., Estruch, R., Lamuela-Raventós, R.M., Martínez-González, M.A., Salas-Salvadó, J., …Andres-Lacueva, C. (2013, Feb 25). Mediterranean diet and non enzymatic antioxidant capacity in the PREDIMED study: Evidence for a mechanism of antioxidant tuning [Abstract]. Nutr Metab Cardiovasc Dis, Epub ahead of print. doi: 10.1016/j.numecd.2012.12.008
- Buckland, G., Traviera, N., Barricarte, A., Ardanaz, E., Moren0-Iribas, C., Sánchez, M-J., …Gonzalez, C.A. (2012). Olive oil intake and CHD in the European Prospective Investigation into Cancer and Nutrition Spanish cohort [Abstract]. British Journal of Nutrition, 108(11): 2075-2082. doi: 10.1017/S000711451200298X
- Astrup, A., Dyerberg, J., Elwood, P., Hermansen, K., Hu, F.B., Jakobsen, M.U., …Willett, W.C. (2011). The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: Where does the evidence stand in 2010? [PDF]. Am J Clin Nutr, 93(4): 684–8. doi: 10.3945/ ajcn.110.004622
- Miller, D.W. (2011, Jul 19). Enjoy saturated fats, they’re good for you! Retrieved from http://lewrockwell.com/miller/miller38.1.html
- Legrand, P. (2009). Origin, metabolism and biological functions of saturated fatty acids [PPT]. Retrieved from http://www.aocs.org/files/resourcespdf/legrand-aocs-orlando-09-transmis.pdf
- Feinman, R.D. (2010, Oct). Saturated fat and health: Recent advances in research [Abstract]. Lipids, 45(10): 891–892. doi: 10.1007/s11745-010-3446-8
- Assunção, M.L., Ferreira, H.S., dos Santos, A.F., Cabral, C.R. Jr., & Florêncio, T.M. (2009, Jul). Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity [Abstract]. Lipids, 44(7): 593-601. doi: 10.1007/s11745-009-3306-6
- Legrand, P. & Rioux, V. (2010, Oct). The complex and important cellular and metabolic functions of saturated fatty acids [PDF]. Lipids, 45(10): 941–946. doi: 10.1007/s11745-010-3444-x