Unsaturated fat
From Free net encyclopedia
An unsaturated fat is a fat or fatty acid in which there is one or more double bond in the fatty acid chain. Fat molecules are monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. Double bonds, which are sometimes referred to as unsaturated bonds, may be cis or trans.
Examples of common unsaturated fats are palmitoleic acid, oleic acid, linoleic acid, and arachidonic acid.
Foods containing unsaturated fats include avocado, nuts, and soybean, canola, and olive oils. Meat products contain both saturated and unsaturated fats.
Both mono- and polyunsaturated fats can replace saturated fat in the diet; trans unsaturated fats should be avoided. Substituting saturated fats with unsaturated fats helps to lower levels of total cholesterol and LDL cholesterol in the blood. This effect is attributed to the low melting point of unsaturated fats found in food. 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 unsaturated fats are not as unhealthy as saturated fats, the amount of unsaturated fat consumed should not exceed 30% of one's daily caloric intake (or 67 grams given a 2000 calorie diet).
See also
- Saturated fat
- Unsaturated fat