Fructose is present in most fruits and many vegetables. It makes up half of table sugar, being combined with glucose to make sucrose. In small amounts it causes no problems. In large amounts it contributes to hypertension and fatty liver. A diet of high potassium foods naturally limits fructose, so fructose does not need to be of concern.
On the modern American diet, the average American eats about 55 gm of fructose. Approximately 100 years ago the average American ate about 15 gm of fructose. Most of the increase comes in the form of beverages containing sugar, specifically sodas. Sodas are not one of the high potassium foods.
Other sources are the high fructose syrups added to many foods to sweeten them. If you are eating a high potassium diet, you are eating mostly foods as they are found in nature, so you are avoiding dishes with added fructose. The fruit and vegetables in the high potassium diet will contribute about 15 gm of fructose, about the same as your ancestors consumed in the early twentieth century.
There are two bad direct effects from excessive fructose in the diet. One is that it causes the liver to process the extra fructose (the only place it can be processed) into excessive fatty acids and triglycerides. When their levels get too high they contribute to plaque in the arteries, and accumulation of fat in the liver cells. This leads to nonalcoholic fatty liver disease (NAFLD), and a reduction in liver function. Up to a third of American adults have some form of NAFLD.
Another undesirable effect of too much fructose is increased sodium resorption and absorption. The intestinal cells absorb more sodium in the presence of fructose, and the kidney cells resorb more sodium. Too much sodium and not enough potassium in the body contribute to hypertension, osteoporosis and kidney stones.
However if you are on the high potassium diet, you are getting more than 3 times as much potassium as sodium. You are protecting yourself from these possible effects that others on a low potassium diet will get as a result of the increased sodium resorption.
How much is too much fructose? There is no sharp line between enough and too much. Fifteen grams a day should be fine. Fifty five grams may be too much. 55 gm of fructose is about 22 teaspoons of sugar, since half of sugar (sucrose) is glucose and half is fructose.
If you are eating the portions we discussed in this post, you will avoid getting too much fructose. Even if your fruit and vegetable portions are mostly fruit you should be in a very healthy range.
Next post will include a table of the high potassium fruits with the amount of fructose they contain.
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