Fat that occurs naturally in living matter contains varying proportions of saturated and unsaturated fat. Foods that contain a high proportion of saturated fat are dairy products (especially cream and cheese but also butter and ghee), animal fats such as suet, tallow, lard and fatty meat, coconut oil, cottonseed oil, palm kernel oil and chocolate, and some prepared foods.
There are several kinds of naturally occurring saturated fatty acids, their only difference being the number of carbon atoms - from 1 to 24. Saturated fatty acids have no double bonds between the carbon atoms of the fatty acid chain; hence, they are fully saturated with hydrogen atoms.
While nutrition labels usually lump them together, 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, chocolate and nuts is primarily palmitic and stearic acid.
|Food||Lauric acid||Myristic acid||Palmitic acid||Stearic acid|
Some common examples of fatty acids are:
Harvard Nurses' Health Study found that diets lower in carbohydrate and higher in protein and animal fat are associated with a statistically insignificant decrease in risk of coronary heart disease in women. When vegetable sources of fat and protein are chosen, these diets may moderately reduce the risk of coronary heart disease."
Diets high in saturated fat are correlated with an increased incidence of atherosclerosis and coronary heart disease according to a number of studies, both African green monkeys and human, such as a study of infant diets , 22 hypercholesterolemic men Some studies have suggested that diets high in saturated fat increase the risk of heart disease and stroke. Epidemiological studies have found that those whose diets are high in saturated fatty acids, including lauric, myristic, palmitic, and stearic acid, had a higher prevalence of coronary heart disease. Additionally, controlled experimental studies have found that people consuming high saturated fat diets experience negative cholesterol profile changes. A 2003 meta-analysis published in the American Journal of Clinical Nutrition concluded that diets high in saturated fat negatively affected cholesterol profiles — predictors of a heart attack and other cardiovascular diseases.
Experiments in which subjects were randomly assigned to either a control or Mediterranean diet (which replaces saturated fat with mono and polyunsaturated fat) showed that subjects assigned to a Mediterranean diet exhibited a significantly decreased likelihood of suffering a second heart attack, cardiac death, heart failure or stroke.
Epidemiological studies of heart disease have implicated the four major saturated fatty acids to varying degrees. The World Health Organization has determined that there is "convincing" evidence that myristic and palmitic acid intake increases the probability, "possible" risk from lauric acid, and no increased risk at all from stearic acid consumption.
In a study published in 2001, erythrocyte membrane oleic and monounsaturated fatty acid content was positively associated with breast cancer risk in postmenopausal women, while no association was shown between saturated fatty acids and breast cancer risk. Enzyme Δ9-desaturase catalyzes the conversion of stearic acid to oleic acid: there is a negative correlation between erythrocyte membrane oleic acid and dietary polyunsaturated fatty acids. Inverse relationship between Saturation Index (ratio of membrane stearic to oleic acid) and breast cancer risk could also be related to hormonal and metabolic factors and to interactions between them, as well as to dietary factors.
The World Health Organization (WHO) has concluded that saturated fats negatively affect cholesterol profiles, predisposing individuals to heart disease, and recommends avoiding saturated fats in order to reduce the risk of a cardiovascular disease.
Another confounding issue may be the formation of exogenous (outside the body) advanced glycation endproducts (AGEs) and oxidation products generated during cooking, which it appears some of the studies have not controlled for. It has been suggested that, "given the prominence of this type of food in the human diet, the deleterious effects of high-(saturated)fat foods may be in part due to the high content in glycotoxins, above and beyond those due to oxidized fatty acid derivatives."  The glycotoxins, as he called them, are more commonly called AGEs