Colorful, tasty, sweet, and full of vitamins, minerals, fiber, phytochemicals, and other nutrients, fruit brings a ton to the table. Believe me, I eat some every day. There are berries, tree fruit, and even disguised guys like avocados, coconuts, olives, these last three even containing great sources of fat. In fact, corn and tomatoes are technically even fruit.
Of consideration though, and the point of this piece, is fruit's sugar content. Sure fruit is healthy, but keeping carbohydrate consumption under 150 grams/day is ideal in the Paleo context, less if you are trying to lose weight. The body does prefer fat for fuel and has no dietary carbohydrate requirements. Vegetables and fruit are good sources of carbohydrates, yet the majority of people use grains and starches, or even worse, drink their carbohydrates in soda and fake juices. As discussed in my previous article on Sugar, fruit contains fructose, which must be shipped to the liver before entering the bloodstream as glucose. Fruits vary in their amount of fructose/glucose amounts, so check out this Table of Fruits & Sugars as prepared by Loren Cordain. So, fruit is not bad, but it can and does add to the daily sugar tally. Too much sugar and the resulting blood glucose, from whatever the source, too often, bad things can happen.
Daily Sugar Intake
Not to send out a panic of 'Bill hates fruit!', but you have to be careful about the amount and sources you are getting your sugar from. We're talking total sugar here folks, not just the white stuff. If you are eating bread, cereal, pasta, potatoes, or rice, (all easily digestible refined carbohydrates), and then top it off with a little fruit, then your sugar intake is surely through the roof. Ideally, your Carb intake should come from vegetables first, supplemented with a little fruit.
Sugar, and especially HFCS is hidden in tons of foods which adds to the average yearly tally of 160 pounds per person. (that is average folks!)
Bread, pasta, and cereal are obvious culprits of simple, refined, and easily digestible carbohydrates, but HFCS sneaks into everything from yogurt, pasta sauce, and juice. Realize that High Fructose Corn Syrup is simply sugar from corn that has been refined and concentrated comprised of 55% fructose and 45% glucose.
The Potential Problems with Fructose
Unlike glucose which goes into circulation following digestion in the small intestine, fructose must make a pit stop at the Liver first. A few things can happen in the Liver:
- Fructose can get converted to glucose and enter circulation to be used as energy...fine!
- Fructose can be converted to glucose and stored in the Liver for a later day, stored energy reserve if you will. You can store a little, not too much...fine!
- The bloodstream is already full of glucose and doesn't need anymore. At this point, the liver converts fructose to triglycerides, (a form of fat), packs it with cholesterol, proteins, and ships out an LDL to transport these goodies to cells. Not a problem...to a point, but too much LDL is a problem and a risk for heart disease, as you know..not good! (your doctor didn't tell you fructose can raise your LDL...did he/she???)
- The bloodstream is swimming with glucose, liver storage is full, cells are full, too much fructose is coming in at a rapid and regular pace, the liver gets backed up, it converts and stores fat...you get a fatty liver...not good!
Read: Fatty Liver Disease
To Summarize...and add to:
- All carbohydrates, vegetables and grains get converted to glucose.
- Glucose causes the release of Insulin
- Fruit has fructose which must be metabolized in the liver first.
- If there is too much glucose already in circulation, fructose gets converted to triglycerides. read this
- If there is a back-up of cholesterol and glucose already in circulation, the liver will store the converted fructose (triglycerides) and a create fatty liver.
- An overload of fructose, and the metabolic processes it takes to convert it, can increase the production of uric acid, which can be implicated in gout and kidney stones, among other things.
- Excess consumption of fructose, especially high fructose corn syrup, can cause the body to retain sodium creating hypertension. This condition is called Fructose-Induced Hypertension.
- Increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload, thus setting in motion a cascade of events that will lead to hypertension.
So, the takeaway is that fruit, in moderation and varied often is healthy. Too much intake of overall sugar, which is hidden in so many items as high fructose corn syrup HFCS, adds to the tab creating numerous health problems. Fruit, even though healthy in moderate doses must be recognized as an addition to daily sugar intake and its load and demand on the liver is to be of consideration.
"If you are very much overweight or are insulin resistant, I recommend
that you initially limit high sugar fruits (grapes, bananas, mangoes,
sweet cherries, apples, pineapples, pears and kiwi fruit) from your diet
until your weight starts to normalize and your health improves."
-Leavitt Oct. 2012