|Saturated Fats and the Kidneys|
|Written by Mary G. Enig, PhD|
|Saturday, 30 September 2000 19:31|
One of the body's most important organs is the kidney. Properly functioning kidneys are essential for maintaining proper blood volume and composition; for filtering and excreting or saving various chemical metabolites; and for helping to maintain proper blood pressure. Hypertension (high blood pressure) is known to result from improperly functioning kidneys. Research carried out during the last few years indicates that both saturated fat and cholesterol play important roles in maintaining kidney function, as do the omega-3 fatty acids.
The kidneys need stable fats both for their cushioning and as their energy source. We know that the kidney fat normally has a higher concentration of the important saturated fatty acids than are found in any of the other fat depots. These saturated fatty acids are myristic acid (the 14-carbon saturate), palmitic acid (the 16-carbon saturate), and stearic acid (the 18-carbon saturate). When we consume various polyunsaturated fatty acids in large amounts, they are incorporated into kidney tissues, usually at the expense of oleic acid, because the normal high level of saturated fatty acids in the kidney fat does not change.1
A species of rat known to be prone to strokes and to spontaneously develop hypertension (high blood pressure) has been used to evaluate effects of different lipids such as plant sterols or cholesterol, and also fatty acids such as omega-3 or omega-6 fatty acids in the finely tuned functions of the kidney. These animals are very sensitive to dietary cholesterol manipulations and a deficiency of cholesterol in their membranes makes their membranes weak and fragile. When plant sterols found in vegetable oils are substituted for cholesterol in their diets, these animals have a shortened life span.2 Also, these animals are reported to need a proper omega-6 to omega-3 ratio in the kidney phospholipids. It was further reported that feeding oils high in omega-6 fatty acids without omega-3 fatty acids resulted in renal injury, and that feeding oils rich in the omega-3 fatty acids such as fish oil, perilla oil, and flaxseed oil prolonged the survival time of this animal.3
The omega-3 fatty acids are recognized as being important, and the conversion of the flax oil-type omega-3 fatty acid (alpha-linolenic acid) to the fish oil-type omega-3 fatty acids (EPA and DHA) is enhanced when the diet contains saturated fat such as coconut oil. This conversion is hindered when there is extra omega-6 oils in the diet.4 Injury to the kidney from immune dysfunction (IgA nephropathy) responds to omega-3 fats (both flax oil-type omega-3 and fish oil-type omega-3).5 As noted, adding the saturated fats, especially coconut oil, improves the body's use of omega-3 fatty acids.
Another reason that coconut oil enhances kidney function is because it supplies myristic acid, the 14-carbon saturated fatty acid.6 Myristic acid is involved in the signalling from cell membrane receptors through G proteins and their attachment to membranes. These signalling proteins require a lipid such as myristic acid to be added to one end of the protein, a process called myristolation.7
Thus, the fats that we recommend for general good health, namely various saturated animal fats and tropical oils, along with a supplement of flax oil, are also specifically helpful for kidney function. Products containing high omega-6 oils and trans fatty acids should be avoided.
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written by tom bernardy, May 29 2011
|Last Updated on Friday, 05 June 2009 23:16|