A saturated fat is a type of fat in which the fatty acid chains have all or predominantly single bonds. A fat is made of two kinds of smaller molecules: glycerol and fatty acids. Fats are made of long chains of carbon (C) atoms. Some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). Double bonds can react with hydrogen to form single bonds. They are called saturated, because the second bond is broken and each half of the bond is attached to (saturated with) a hydrogen atom. Most animal fats are saturated. The fats of plants and fish are generally unsaturated. Saturated fats tend to have higher melting points than their corresponding unsaturated fats, leading to the popular understanding that saturated fats tend to be solids at room temperatures, while unsaturated fats tend to be liquid at room temperature with varying degrees of viscosity (meaning both saturated and unsaturated fats are found to be liquid at body temperature).
Various fats contain different proportions of saturated and unsaturated fat. Examples of foods containing a high proportion of saturated fat include animal fat products such as cream, cheese, butter, other whole milk dairy products and fatty meats which also contain dietary cholesterol. Certain vegetable products have high saturated fat content, such as coconut oil and palm kernel oil. Many prepared foods are high in saturated fat content, such as pizza, dairy desserts, and sausage.
Guidelines released by many medical organizations, including the World Health Organization, have advocated for reduction in the intake of saturated fat to promote health and reduce the risk from cardiovascular diseases. Many review articles also recommend a diet low in saturated fat and argue it will lower risks of cardiovascular diseases,diabetes, or death. A small number of contemporary reviews have challenged these conclusions, though predominant medical opinion is that saturated fat and cardiovascular disease are closely related.
While nutrition labels regularly combine them, the saturated fatty acids appear in different proportions among food groups. Lauric and myristic acids are most commonly found in "tropical" oils (e.g., palm kernel, coconut) and dairy products. The saturated fat in meat, eggs, cacao, and nuts is primarily the triglycerides of palmitic and stearic acids.
|Food||Lauric acid||Myristic acid||Palmitic acid||Stearic acid|
|Palm kernel oil||48%||1%||44%||5%|
Some common examples of fatty acids:
|As weight percent (%) of total fat|
|Palm kernel oil||86||12||02|
|Rice bran oil||25||38||37|
|Safflower oil, high oleic||06||75||14|
|Safflower oil, linoleic||06||14||75|
|Ice cream, gourmet||62||29||04|
|Ice cream, light||62||29||04|
|Fish, orange roughy||23||15||46|
|Hot dog, beef||42||48||05|
|Hot dog, turkey||28||40||22|
|Burger, fast food||36||44||06|
|Cheeseburger, fast food||43||40||07|
|Breaded chicken sandwich||20||39||32|
|Grilled chicken sandwich||26||42||20|
|Almonds dry roasted||09||65||21|
|Cashews dry roasted||20||59||17|
|Macadamia dry roasted||15||79||02|
|Peanut dry roasted||14||50||31|
|Pecans dry roasted||08||62||25|
|Walnuts dry roasted||09||23||63|
|Sweets and baked goods|
|Candy, chocolate bar||59||33||03|
|Candy, fruit chews||14||44||38|
|Cookie, oatmeal raisin||22||47||27|
|Cookie, chocolate chip||35||42||18|
|Fats added during cooking or at the table|
|Margarine, light tub||19||46||33|
|Dressing, blue cheese||16||54||25|
|Dressing, light Italian||14||24||58|
|Egg yolk fat||36||44||16|
|Unless else specified in boxes, then reference is:|
|* 3% is trans fats|
There are strong, consistent, and graded relationships between saturated fat intake, blood cholesterol levels, and the epidemic of cardiovascular disease. The relationships are accepted as causal.
Many health authorities such as the Academy of Nutrition and Dietetics, the British Dietetic Association,American Heart Association, the World Heart Federation, the British National Health Service, among others, advise that saturated fat is a risk factor for cardiovascular disease. The World Health Organization in May 2015 recommends switching from saturated to unsaturated fats.
A small, limited number of systematic reviews have examined the relationship between saturated fat and cardiovascular disease and have come to different conclusions.
A 2017 systematic review by the American Heart Association of randomized controlled clinical trials showed that reducing intake of dietary saturated fat and replacing it with monounsaturated and polyunsaturated fats could reduce cardiovascular disease by about 30%, similar to the reduction achieved by statin treatment for maintaining blood cholesterol within normal limits.
A different 2017 systematic review of randomized, controlled trials concluded that replacing saturated fats with mostly n-6 polyunsaturated fats is unlikely to reduce coronary heart disease (CHD) events, CHD mortality or total mortality. The 2017 review showed that inadequately controlled trials (e.g., failing to control for other lifestyle factors) that were included in earlier meta-analyses explain the prior results.
A 2015 systematic review also found no association between saturated fat consumption and risk of heart disease, stroke, or diabetes. However, this study only looked at observational studies, and can therefore not be used to determine cause and effect.
A 2014 systematic review looking at observational studies of dietary intake of fatty acids, observational studies of measured fatty acid levels in the blood, and intervention studies of polyunsaturated fat supplementation concluded that the findings ?do not support cardiovascular guidelines that promote high consumption of long-chain omega-3 and omega-6 and polyunsaturated fatty acids and suggest reduced consumption of total saturated fatty acids.? Researchers acknowledged that despite their results, further research is necessary, especially in people who are initially healthy. Due to potential weaknesses in this review, experts recommend people remain with the current guidelines to reduce saturated fat consumption. The American Heart Association noted that these cohort studies, unlike clinical trials, have more difficulty controlling for the consumption of carbohydrates as a replacement macronutrient for those who consumed less saturated fat.
|American Heart Association, 2017||"Cardiovascular disease (CVD) is the leading global cause of death, accounting for 17.3 million deaths per year, comprising 31.5% of total global deaths in 2013. In 2014, nearly 808,000 people in the United States died of heart disease, stroke, and other CVDs, translating to about 1 of every 3 deaths. Lowering intake of dietary saturated fat and replacing it with monounsaturated and polyunsaturated vegetable oil reduced CVD by about 30%, similar to the reduction achieved by statin treatment."|
|DiNicolantonio, 2016||Many lines of evidence implicate added sugars more than saturated fat as etiologic in CHD. We urge dietary guidelines to shift focus away from recommendations to reduce saturated fat and toward recommendations to avoid added sugars.|
|Harcombe, 2015||No reduction in CHD and all-cause mortality were observed when replacing saturated fat with polyunsaturated fat, even though reductions in serum cholesterol were observed.|
|de Souza, 2015||Saturated fats are not associated with all cause mortality, CVD, CHD, ischemic stroke, or type 2 diabetes, but the evidence is heterogeneous with methodological limitations.|
|Schwab, 2014||There was convincing evidence that partial replacement of saturated fat with polyunsaturated fat decreases the risk of cardiovascular diseases, especially in men.|
|Chowdhury, 2014||High levels of saturated fat intake had no effect on coronary disease. The evidence did not clearly support cardiovascular guidelines that encouraged high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.|
|Hooper, 2012||Reducing saturated fat in diets did not reduce mortality, despite reducing the risk of having a cardiovascular event by 14 percent.|
|Micha, 2010||Based on consistent evidence from human studies, replacing saturated fatty acids with polyunsaturated fat modestly lowers coronary heart disease risk, with ~10% risk reduction for a 5% energy substitution; whereas replacing SFA with carbohydrate has no benefit and replacing SFA with monounsaturated fat has uncertain effects.|
|Mozaffarian, 2010||These findings provide evidence that consuming polyunsaturated fats (PUFA) in place of SFA reduces Coronary Heart Disease (CHD) events in randomized controlled trials (RCT). Replacing saturated fats with PUFAs as percentage of calories strongly reduced CHD mortality.|
|Siri-Tarino, 2010||5-23 years of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.|
|Danaei, 2009||Low PUFA intake has a 1-5% Increased risk of ischemic heart disease: Low dietary PUFA (in replacement of SFA). age 30-44 Increase in RR 1.05.|
|Mente, 2009||Single-nutrient RCTs have yet to evaluate whether reducing saturated fatty acid intake lowers the risk of CHD events. For polyunsaturated fatty acid intake, most of the RCTs have not been adequately powered and did not find a significant reduction in CHD outcomes.|
|Skeaff, 2009||Intake of SFA was not significantly associated with CHD mortality, with a RR of 1.14. Moreover, there was no significant association with CHD death. Intake of PUFA was strongly significantly associated with CHD mortality, with a RR of 1.25. The Health Professionals Follow-up Study and the EUROASPIRE study results mirrored those of total PUFA; intake of linoleic acid was significantly associated with CHD mortality.|
|Jakobsen, 2009||"The associations suggest that replacing saturated fatty acids with polyunsaturated fatty acids rather than monounsaturated fatty acids or carbohydrates prevents CHD over a wide range of intakes."|
|Van Horn, 2008||25-35% fats but <7% SFA and TFA reduces risk.|
While many studies have found that including polyunsaturated fats in the diet in place of saturated fats produces more beneficial CVD outcomes, the effects of substituting monounsaturated fats or carbohydrates are unclear.
Abnormal blood lipid levels, that is high total cholesterol, high levels of triglycerides, high levels of low-density lipoprotein (LDL, "bad" cholesterol) or low levels of high-density lipoprotein (HDL, "good" cholesterol) cholesterol are all associated with increased risk of heart disease and stroke.
Meta-analyses have found a significant relationship between saturated fat and serum cholesterol levels. High total cholesterol levels, which may be caused by many factors, are associated with an increased risk of cardiovascular disease. However, other indicators measuring cholesterol such as high total/HDL cholesterol ratio are more predictive than total serum cholesterol. In a study of myocardial infarction in 52 countries, the ApoB/ApoA1 (related to LDL and HDL, respectively) ratio was the strongest predictor of CVD among all risk factors. There are other pathways involving obesity, triglyceride levels, insulin sensitivity, endothelial function, and thrombogenicity, among others, that play a role in CVD, although it seems, in the absence of an adverse blood lipid profile, the other known risk factors have only a weak atherogenic effect. Different saturated fatty acids have differing effects on various lipid levels.
A meta-analysis published in 2003 found a significant positive relationship in both control and cohort studies between saturated fat and breast cancer. However two subsequent reviews have found weak or insignificant associations of saturated fat intake and breast cancer risk, and note the prevalence of confounding factors.
One review found limited evidence for a positive relationship between consuming animal fat and incidence of colorectal cancer.
Some researchers have indicated that serum myristic acid and palmitic acid and dietary myristic and palmitic saturated fatty acids and serum palmitic combined with alpha-tocopherol supplementation are associated with increased risk of prostate cancer in a dose-dependent manner. These associations may, however, reflect differences in intake or metabolism of these fatty acids between the precancer cases and controls, rather than being an actual cause.
Mounting evidence indicates that the amount and type of fat in the diet can have important effects on bone health. Most of this evidence is derived from animal studies. The data from one study indicated that bone mineral density is negatively associated with saturated fat intake, and that men may be particularly vulnerable.
Recommendations to reduce or limit dietary intake of saturated fats are made by the World Health Organization, American Heart Association, Health Canada, the US Department of Health and Human Services, the UK Food Standards Agency, the Australian Department of Health and Aging, the Singapore Government Health Promotion Board, the Indian Government Citizens Health Portal, the New Zealand Ministry of Health, the Food and Drugs Board Ghana, the Republic of Guyana Ministry of Health, and Hong Kong's Centre for Food Safety.
In 2003, the World Health Organization (WHO) and Food and Agriculture Organization (FAO) expert consultation report concluded that "intake of saturated fatty acids is directly related to cardiovascular risk. The traditional target is to restrict the intake of saturated fatty acids to less than 10% of daily energy intake and less than 7% for high-risk groups. If populations are consuming less than 10%, they should not increase that level of intake. Within these limits, intake of foods rich in myristic and palmitic acids should be replaced by fats with a lower content of these particular fatty acids. In developing countries, however, where energy intake for some population groups may be inadequate, energy expenditure is high and body fat stores are low (BMI <18.5 kg/m2). The amount and quality of fat supply has to be considered keeping in mind the need to meet energy requirements. Specific sources of saturated fat, such as coconut and palm oil, provide low-cost energy and may be an important source of energy for the poor."
A 2004 statement released by the Centers for Disease Control (CDC) determined that "Americans need to continue working to reduce saturated fat intake..." In addition, reviews by the American Heart Association led the Association to recommend reducing saturated fat intake to less than 7% of total calories according to its 2006 recommendations. This concurs with similar conclusions made by the US Department of Health and Human Services, which determined that reduction in saturated fat consumption would positively affect health and reduce the prevalence of heart disease.
The United Kingdom, National Health Service claims the majority of British people eat too much saturated fat. The British Heart Foundation also advises people to cut down on saturated fat. People are advised to cut down on saturated fat and read labels on food they buy.
A 2004 review stated that "no lower safe limit of specific saturated fatty acid intakes has been identified" and recommended that the influence of varying saturated fatty acid intakes against a background of different individual lifestyles and genetic backgrounds should be the focus in future studies.
Blanket recommendations to lower saturated fat were criticized at a 2010 conference debate of the American Dietetic Association for focusing too narrowly on reducing saturated fats rather than emphasizing increased consumption of healthy fats and unrefined carbohydrates. Concern was expressed over the health risks of replacing saturated fats in the diet with refined carbohydrates, which carry a high risk of obesity and heart disease, particularly at the expense of polyunsaturated fats which may have health benefits. None of the panelists recommended heavy consumption of saturated fats, emphasizing instead the importance of overall dietary quality to cardiovascular health.
In a 2017 comprehensive review of the literature and clinical trials, the American Heart Association published a recommendation that saturated fat intake be reduced or replaced by products containing monounsaturated and polyunsaturated fats, a dietary adjustment that could reduce the risk of cardiovascular diseases by 30%.
The two-dimensional illustration has implicit hydrogen atoms bonded to each of the carbon atoms in the polycarbon tail of the myristic acid molecule (there are 13 carbon atoms in the tail; 14 carbon atoms in the entire molecule).
Carbon atoms are also implicitly drawn, as they are portrayed as intersections between two straight lines. "Saturated," in general, refers to a maximum number of hydrogen atoms bonded to each carbon of the polycarbon tail as allowed by the Octet Rule. This also means that only single bonds (sigma bonds) will be present between adjacent carbon atoms of the tail.