We are often told to avoid saturated fats, and to get good fats instead of bad fats in our diet. What are good fats and what is it about them that makes them good? And what do they have to do with high potassium foods?
Cell Membranes Are Made Of Fat
The fats we eat go into the membranes of our cells. Proteins are located in these membranes, and go across the membrane from one side of the membrane to the other side. These proteins change shape to do the work of the cell to keep us healthy.
Two important types of proteins that cross the cell membranes are channels and pumps. The channels and pumps move potassium and sodium back and forth across the cell membranes. The difference in concentration of potassium and sodium inside and outside the cell creates an electric field. Changes in this electric field drive the work of the cell.
If the electric field cannot change quickly enough, the cell cannot do its work properly. For the electric field to change quickly, the channels and pumps must move potassium and sodium quickly.
The channels and pumps sit in cell membranes, which are composed of fats (lipids). The type of lipids in the cell membrane may affect how well the channels and pumps that sit in the membrane work.
Why Bad Fats And Good Fats Make A Difference
A recent study (1) gives insight into how the lipids in the cell membranes affect how well one particular potassium channel functions. The particular channel the researchers investigated is one of the most studied potassium channels. This channel demonstrates how the function of other channels and pumps also may be affected by the composition of the cell membranes.
The researchers showed that the pore that lets potassium flow through the channel is fine-tuned by the physical characteristics of the lipid in the cell membrane. When the membrane allows protein in the pore of the channel to change more easily, potassium can get through faster.
This study changed two characteristics of the membrane that potassium channels sit in. The two characteristics of the membrane that the researchers changed were the temperature of the membrane, and the type of fats the membrane was made of. Both of these characteristics changed the fluidity of the membrane.
The researchers then determined whether the fluidity of the membrane had any effect on the channel. They measured whether the channel was open, and how much potassium could flow through it.
The researchers found that the more fluid the cell membrane, the more easily the shape of the proteins in the channel could change. The channel was more likely to be open, and was able to conduct more potassium ions through the channel more quickly.
The researchers felt these findings could be generalized to other factors affecting the cell membranes. Other possible factors affecting the fluidity of the membranes were likely to affect the flow of potassium by affecting how easily the channel can change shape.
There have been a great number of epidemiologic studies that show less cardiovascular disease in those who eat less saturated fat. (Arachidic acid is the saturated fat shown above.) There is also less cardiovascular disease in those who consume more polyunsaturated and monounsaturated fats. It has not been clear how this reduction in cardiovascular disease occurs. However this study shows one of the ways the type of fat eaten affects health.
Fluid Membranes Are Best
Saturated fats make cell membranes stiffer. This is why saturated fats are bad fats. They slow the channels that allow the electric field in cells to change the shape of proteins. The proteins cannot do as much work as they should.
Polyunsaturated fats and monounsaturated fats are good fats because they make the cell membrane more fluid. Thus, the polyunsaturated and monounsaturated fats allow the potassium channels and sodium channels to perform more efficiently. The cell can then maintain the best potassium sodium ratio. The electric field in the cell can change more quickly, allowing proteins in the cell to change shape more easily to do their work.
By maintaining a high potassium sodium ratio in your diet, and by maintaining a high ratio of polyunsaturated and monounsaturated fats to saturated fat in your diet, you can maintain the best environment for cellular function.
1. Changes in single K(+) channel behavior induced by a lipid phase transition. Seeger HM, Aldrovandi L, Alessandrini A, Facci P. Biophys J. 2010 Dec 1;99(11):3675-83. doi: 10.1016/j.bpj.2010.10.042.