What are the health effects of saturated rather than unsaturated fat?!
Question: I've started reading nutrition labels lately, and I've noticed that in a lot of really good-tasting stuff there is an excess of saturated fat, at least compared to daily value. For instance, on a tub of ice cream they list the gallon as having, say, 20 servings with 20% saturated fat DV each.
Now, my question is, how does saturated fat affect one's health, and how are its effects different than that of unsaturated fat?
Answers: I've started reading nutrition labels lately, and I've noticed that in a lot of really good-tasting stuff there is an excess of saturated fat, at least compared to daily value. For instance, on a tub of ice cream they list the gallon as having, say, 20 servings with 20% saturated fat DV each.
Now, my question is, how does saturated fat affect one's health, and how are its effects different than that of unsaturated fat?
Saturated fat is found to increase cholesterol production by the body. It also decreases insulin sensitivity, which causes body to store food more often as fat, rather than other uses.
That being said, saturated does have some vital functions. It helps control the activity of the thyroid and its hormones. But the typical american diet has so much saturated fat already in it that efforts should be made to decrease it.
Unsatuared fat are of two types - monounsaturated and polyunsaturated. Both are considered as good fats - they appear to reduce cholesterol levels. But still excess consumption of these will result in the body storing them again as adipose tissue. Adipose tissue in iteslf tends to decrease insuling sensitivity.
Unsaturated fats are made up of Polyunsaturated fats and Mono unsaturated. Polyunsaturated and Mono-unsaturated are beneficial to the health and help lower cholesterol, not raise it. Saturated fat sticks to the arteries and causes high blood pressure. It raises HDL cholesterol which is the bad cholesterol. Polyunsaturated fats contain fats such as Omega 3, 6 and 9 which are needed by the cells in the body to help absorb nutrients and to help keep cells fluid. The brain needs these good fats. They help transport fat soluble vitamins. They help lower cholesterol.
[UNSATURATED FAT]
An unsaturated fat is a fat or fatty acid in which there are one or more double bonds in the fatty acid chain. A fat molecule is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. Where double bonds are formed, hydrogen atoms are eliminated. Thus, a saturated fat is "saturated" with hydrogen atoms. In cellular metabolism hydrogen-carbon bonds are broken down - or oxidized - to produce energy, thus an unsaturated fat molecule contains somewhat less energy (i.e fewer calories) than a comparable sized saturated fat. The greater the degree of unsaturation in a fatty acid (ie, the more double bonds in the fatty acid), the more vulnerable it is to lipid peroxidation (rancidity). Antioxidants can protect unsaturated fat from lipid peroxidation. Unsaturated fats also have a more enlarged shape than saturated fats.
[Chemistry and Nutrition]
Double bonds may be in either a cis or trans isomer, depending on the geometry of the double bond. In the cis conformation hydrogens are on the same side of the double bond, whereas in the trans conformation they are on opposite sides (see also Trans fat). Saturated fats are popular with manufacturers of processed foods because they are less vulnerable to rancidity and are generally more solid at room temperature than unsaturated fats. Unsaturated chains have a lower melting point, hence increasing fluidity of the cell membranes.
Both mono- and polyunsaturated fats can replace saturated fat in the diet; trans unsaturated fats should be avoided. Substituting (replacing) saturated fats with unsaturated fats helps to lower levels of total cholesterol and LDL cholesterol in the blood. Trans unsaturated fats are particularly bad because the double bond stereochemistry allows the fat molecules to assume a linear conformation which leads to efficient packing (i.e., plaque formation). The geometry of the cis double bond introduces a bend in the molecule precluding stable formations (see specific fatty acid links above for drawings that illustrate this). Natural sources of fatty acids (see above) are rich in the cis isomer.
Although polyunsaturated fats are protective against cardiac arrhythmias a study of post-menopauseal women with a relatively low fat intake showed that polyunsaturated fat was positively associated with progression of coronary atherosclerosis, whereas monounsaturated fat was not [1]. This probably is an indication of the greater vulnerability of polyunsaturated fats to lipid peroxidation, against which Vitamin E has been shown to be protective [2].
Examples of unsaturated fats are palmitoleic acid, oleic acid, linoleic acid, and arachidonic acid. Foods containing unsaturated fats include avocado, nuts, and vegetable oils such as soybean, canola, and olive oils. Meat products contain both saturated and unsaturated fats.
Although unsaturated fats are healthier than saturated fats,[3] the old Food and Drug Administration (FDA) recommendation stated that the amount of unsaturated fat consumed should not exceed 30% of one's daily caloric intake (or 67 grams given a 2000 calorie diet). The new dietary guidelines have eliminated this recommendation. Most food contain both unsaturated and saturated fats. Marketers only advertise one or the other, depending on which makes up the majority. Thus, various unsaturated fat vegetable oils, such as olive oils, also contain saturated fat.
Insulin resistance correlates positively with monounsaturated fat (especially oleic acid) and negatively with polyunsaturated fat (especially arachidonic acid) in the phospholipids of human skeletal muscle [4].
[Membrane composition as a metabolic pacemaker]
Cell membranes of mammals have a higher composition of polyunsaturated fat (DHA, omega-3 fatty acid) and a lower composition of monounsaturated fat than do reptiles. Higher polyunsaturated membrane content gives greater membrane fluidity (and functionality), commensurate with the higher metabolic rate of the warm-blooded species. In fish, however, increasingly cold environments lead to increasingly high cell membrane content of both monounsaturated and polyunsaturated fatty acids, presumably to maintain greater membrane fluidity (and functionality) at the lower temperatures[5]
[SATURATED FAT]
Explanation
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 butter, ghee, suet, tallow, lard, coconut oil, cottonseed oil, and palm kernel oil, dairy products (especially cream and cheese), meat, chocolate, and some prepared foods[1].
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.
saturated fat profile of common foods (percentage of total fat)[2] Food Lauric acid Myristic acid Palmitic acid Stearic acid
Coconut oil 47% 18% 9% 3%
Butter 3% 11% 29% 13%
Ground beef 0% 4% 26% 15%
Dark chocolate 0% 0% 34% 43%
Salmon 0% 1% 29% 3%
Eggs 0% 0% 27% 10%
Cashews 2% 1% 10% 7%
Soybean oil 0% 0% 11% 4%
[ Examples of saturated fatty acids]
Some common examples of fatty acids are:
butyric acid with 4 carbon atoms (contained in butter),
lauric acid with 12 carbon atoms (contained in coconut oil, palm oil and breast milk[citation needed],
myristic acid with 14 carbon atoms (contained in cow milk and dairy products),
palmitic acid with 16 carbon atoms (contained in palm oil, hence the name, and meat),
stearic acid with 18 carbon atoms (also contained in meat and cocoa butter).
[Health issues]
The relationship between dietary fats and CVD, especially coronary heart disease, has been extensively investigated, with strong and consistent associations emerging from a wide body of evidence accrued from animal experiments, as well as observational studies, clinical trials and metabolic studies conducted in diverse human populations...Saturated fatty acids raise total and low-density lipoprotein (LDL) cholesterol...The most effective replacement for saturated fatty acids in terms of coronary heart disease outcome are polyunsaturated fatty acids, especially linoleic acid. This finding is supported by the results of several large randomized clinical trials, in which replacement of saturated and trans fatty acids by polyunsaturated vegetable oils lowered coronary heart disease risk.