Saturated fat
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 atoms. Some carbon atoms are linked by single bonds and others are linked by double bonds. 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 a hydrogen atom.
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.
Most animal fats are saturated. The fats of plants and fish are generally unsaturated. Various foods contain different proportions of saturated and unsaturated fat. Many processed foods like foods deep-fried in hydrogenated oil and sausage are high in saturated fat content. Some store-bought baked goods are as well, especially those containing partially hydrogenated oils. Other examples of foods containing a high proportion of saturated fat and dietary cholesterol include animal fat products such as lard or schmaltz, fatty meats and dairy products made with whole or reduced fat milk like yogurt, ice cream, cheese and butter. Certain vegetable products have high saturated fat content, such as coconut oil and palm kernel oil.
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.
Fat profiles
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 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 |
| Coconut oil | 47% | 18% | 9% | 3% |
| Palm kernel oil | 48% | 1% | 44% | 5% |
| Butter | 3% | 11% | 29% | 13% |
| Ground beef | 0% | 4% | 26% | 15% |
| Salmon | 0% | 1% | 29% | 3% |
| Egg yolks | 0% | 0.3% | 27% | 10% |
| Cashews | 2% | 1% | 10% | 7% |
| Soybean oil | 0% | 0% | 11% | 4% |
Examples of saturated fatty acids
Some common examples of fatty acids:- Butyric acid with 4 carbon atoms
- Lauric acid with 12 carbon atoms
- Myristic acid with 14 carbon atoms
- Palmitic acid with 16 carbon atoms
- Stearic acid with 18 carbon atoms
Association with diseases
Cardiovascular disease
The effect of saturated fat on heart disease has been extensively studied. 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.
There is moderate quality evidence that reducing the proportion of saturated fat in the diet, and replacing it with unsaturated fats or carbohydrates over a period of at least two years, leads to a reduction in the risk of cardiovascular disease.
Dyslipidemia
The consumption of saturated fat is generally considered a risk factor for dyslipidemia, which in turn is a risk factor for some types of cardiovascular disease.Abnormal blood lipid levels, that is high total cholesterol, high levels of triglycerides, high levels of low-density lipoprotein or low levels of high-density lipoprotein 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 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.
Cancer
Breast cancer
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.Colorectal cancer
One review found limited evidence for a positive relationship between consuming animal fat and incidence of colorectal cancer.Ovarian cancer
Meta-analyses of clinical studies found evidence for increased risk of ovarian cancer by high consumption of saturated fat.Prostate 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.Bones
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.Dietary recommendations
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 National Health Service, the Australian Department of Health and Aging, the Singapore Ministry of Health, the Indian Ministry of Health and Family Wellfare, the New Zealand Ministry of Health, and Hong Kong's Department of Health.In 2003, the World Health Organization and Food and Agriculture Organization 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. 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 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%.
Molecular description
The two-dimensional illustration has implicit hydrogen atoms bonded to each of the carbon atoms in the polycarbon tail of the myristic acid 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 will be present between adjacent carbon atoms of the tail.