The Great Fruit Debate
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WifeMomDVM
Posts: 1,025 Member
Sorry this is so long...
Ok my MFPers, in my search to eating as healthy as possible I decided to cut out refined sugars, after searching the boards, I've seen countless posts with people saying eat as much fruit as you want, don't worry about natural sugars, etc... then a little birdie told me that fructose (the natural sugar in fruits) CAN be bad for you. I think what I have taken away from all of this is that small quantities of fruit are ok. Please read the below information and let me know your thoughts... thanks! Also, I've copied and pasted the links for anyone who wants to see where I found my info.
************************************************
First: Is Fruit Sugar Bad For You? http://www.arabianbusiness.com/is-fruit-sugar-bad-for-you--81267.html
It doesn't cause spikes in insulin and blood sugar, but large amounts of fruit sugar (fructose) may contribute to overeating.
Most of the sugar we eat gets broken down and absorbed in the small intestine. Swarms of specialized enzymes attack larger molecules and convert them into three simpler sugars: mainly glucose, but also galactose (a part of lactose, the sugar in milk) and fructose.
There are a few more steps involved in breaking down the starches in bread, potatoes, and the like, but ultimately starch shares a similar digestive fate.
Our livers prudently stow away some of the absorbed glucose as glycogen, a molecule that can be turned back into glucose when we haven't eaten for a while. But most of the sugary stuff is distributed right away. Glucose levels in the blood shoot up, and the pancreas gets busy, pumping out the insulin that cells throughout the body need in order to take in glucose and use it for energy.
Oversupply the metabolic pathway for fructose with this sugar, and the liver ends up churning out triglycerides – fat that circulates in the blood.
Post-meal glucose and insulin spikes are perfectly normal and entirely unavoidable. But if they're too big, or come too often, they're harmful. Canadian researchers devised the glycaemic index (GI) to make it easier to compare how different food affects blood sugar levels: the higher the GI number, the bigger the increase in blood sugar.
A number of studies have found that people who eat a lot of high-GI foods - cookies, sweets, bread made with refined flour, and potatoes - have higher rates of diabetes and heart disease.
Specialised metabolism
Pretty much all of the body's cells come equipped with enzymes that allow them to harness glucose. But the enzyme that metabolises fructose, called fructokinase, is found exclusively in liver cells. So although fructose is involved in glucose metabolism indirectly, fructose metabolism is pretty specialised. As a result, if you eat fructose, your blood glucose and insulin levels stay fairly level.
If, as the GI-index research indicates, glucose and insulin increases are a problem, then replacing other sugars in your diet with fructose looks like it might be a solution.
But, alas, it's more complicated than that. For all the mischief that glucose and insulin cause, they do trigger some helpful hormonal changes. Levels of leptin, the hormone that gives us that "full" feeling, go up when insulin surges, and levels of ghrelin, the "hunger hormone," go down.There's fairly good evidence that fructose has just the opposite effect, reducing leptin, so we don't necessarily feel full after a fructose-filled meal, and not lowering ghrelin as much as glucose does, so we stay hungry. For this reason, some experts see high-fructose diets as contributing to overeating.
And there's another problem: Oversupply the metabolic pathway for fructose with this sugar, and the liver ends up churning out triglycerides - fat that circulates in the blood. The same is true of glucose and its metabolic pathway, but a larger amount of glucose is required to cause an oversupply.
Fructose is a naturally occurring sugar. You'll find it in honey, vegetables (in small amounts), and, of course, fruit. Not all the sugar in fruit is fructose, which is one of the reasons - lack of fibre is another - that some fruit, such as watermelon, have a high glycaemic index.
The great American weight problem and the sweetening of the food supply with the suspect syrup happened at about the same time.
But most people's intake of fructose from fruit and vegetables is dwarfed by what they get from sucrose - better known as table sugar, or just sugar - and high-fructose corn syrup. Sucrose is a two-sugar molecule (a disaccharide) consisting of fructose and glucose. High-fructose corn syrup is corn syrup that has been processed to increase the fructose level, which makes it taste sweeter.
The most common variety is 55% fructose and 45% glucose. In the US, high-fructose corn syrup has replaced sucrose as a sweetener, especially in soft drinks, but in many other types of food too.
Experts debate how responsible high-fructose corn syrup is for the American obesity epidemic and the soaring type 2 diabetes rate. Those who see a connection note that the great American weight problem and the sweetening of the food supply with the suspect syrup happened at about the same time. They also point to fructose metabolism and its triglyceride output.
Skeptics counter with several arguments. Sucrose and high-fructose corn syrup contain about the same amount of fructose and glucose (a 50-50 split versus a 55-45 one), so it's questionable whether the metabolic effects are that different. Further, many of the damning metabolic studies have used all-fructose solutions, not high-fructose corn syrup. And they add, the real problem is all the nutritionally empty, added sugar in our diets, not any particular form of that sugar.
Watch the syrup
Where does this leave us? Certainly no one should stop eating fruit out of some misguided fear of fructose. Most varieties of fruit are brimming with nutritional virtue - vitamins, minerals, fibre - and have relatively little fructose and other sugar.
Is high-fructose corn syrup especially harmful? At this point, the case against food and soft drinks sweetened with the stuff is pretty persuasive.
**********************************************
Ok, so then I wondered, well how much Fructose is too much????
*****************************************************
Next article: Fructose (I did not copy the whole article below - just the highlights I felt were important to this discussion) http://talktomejohnnie.com/diet/fructose
FRUCTOSE
By John | Published: August 22, 2010
John – I was at your most recent CrossFit Football certification and during the nutrition talk you cautioned us about over-consumption of fruit and more specifically fructose. Can you go into more detail on why I should be weary of fructose ?
Consuming large amounts of sugar, especially fructose, has pronounced negative effects on the body. Chronic overconsumption of fructose has been shown to lead the way to obesity, metabolic derangement, diabetes and cancer.
What about fructose?
Fructose can only be metabolized in the liver. The liver can process a decent amount of glucose but it gets full quickly. And while fructose can be used to replenish liver glycogen it does not suppress ghrelin and does not stimulate insulin or leptin secretion. Ghrelin is the hormone that regulates hunger.
So what happens when the liver gets bombarded with fructose and the liver has full glycogen stores?
Once the liver is full of glycogen, the body reacts and starts making fats (palmitic acid) from the fructose and sending them off into the bloodstream as triglycerides.
Excessive amounts of carbohydrates are converted to palmitic acid, a saturated fatty acid; this fatty acid is synthesized into triglycerides and sent into the blood stream. Once palmitic acid hits the blood stream it heads over to the CNS where is does its best to disrupt insulin and leptin signaling.
Everyone is familiar with insulin but what does Leptin do?
Lepin regulates energy intake (appetite) and expenditure. Leptin resistance prevents the brain from detecting its energy reserves or signals of satiety. This results in overeating and changes the body fat mass, which leads to weight gain.
Once liver insulin resistance sets in, the liver becomes a garbage dump releasing glucose into the bloodstream regardless of the levels. The resulting high levels of blood glucose, insulin and triglycerides will stimulate adipocytes (fat cells) to store fat and muscle cells to store glucose as glycogen.
Glucose and fructose become toxic to the cells in high concentrations. Glucose toxicity contributes to the development of diabetes. Long-term effects of glucose toxicity leave individuals with decreased insulin sensitivity. And diabetes develops when insulin production is inadequate for a given level of insulin sensitivity.
How much fructose can the body handle before we start running in to problems?
From my understanding, we can safely process about 50 grams of fructose before things become problematic. That is a pretty low dose of fructose so use the chart below to gauge how much fructose you can consume. We know that problems with fructose are dose-dependent and time-dependent.
There is a table of fruits and sugars on The Paleo Diet listing quantities of sugars in fruits, sweeteners and candies. You can get an idea of which fruits/sugars/foods are highest in fructose, glucose and sucrose. From this you can start to understand where fructose is found in large amounts. Dried fruit is one of the highest on the list (one of the reason we discontinued the sale of beef jerky and dried fruit packs from Paleo Brands), high fructose corn syrup, mangos, apples, oranges, grapes and the amount of fructose in the juice version of these fruits is staggering.
Third: Ok, and lastly here is the table mentioned in the above second article. http://www.thepaleodiet.com/nutritional_tools/fruits_table.html
Ok, I can't copy and paste the table without being a mess so copy and paste the link and take a look, ok?
**************************
So what do you guys think? Should I add sugars to my daily diary and try to keep Fructose under 50 grams a day? Again, sorry if this isn't from scientific journals. Please don't make fun of me if I have become THAT person who believes everything they read on the internet. I mean, come on, if it's on the internet it MUST be true, right (please note sarcasm).
Just would like some thoughts on this, do you think this is true or false? Thanks everyone!
Ok my MFPers, in my search to eating as healthy as possible I decided to cut out refined sugars, after searching the boards, I've seen countless posts with people saying eat as much fruit as you want, don't worry about natural sugars, etc... then a little birdie told me that fructose (the natural sugar in fruits) CAN be bad for you. I think what I have taken away from all of this is that small quantities of fruit are ok. Please read the below information and let me know your thoughts... thanks! Also, I've copied and pasted the links for anyone who wants to see where I found my info.
************************************************
First: Is Fruit Sugar Bad For You? http://www.arabianbusiness.com/is-fruit-sugar-bad-for-you--81267.html
It doesn't cause spikes in insulin and blood sugar, but large amounts of fruit sugar (fructose) may contribute to overeating.
Most of the sugar we eat gets broken down and absorbed in the small intestine. Swarms of specialized enzymes attack larger molecules and convert them into three simpler sugars: mainly glucose, but also galactose (a part of lactose, the sugar in milk) and fructose.
There are a few more steps involved in breaking down the starches in bread, potatoes, and the like, but ultimately starch shares a similar digestive fate.
Our livers prudently stow away some of the absorbed glucose as glycogen, a molecule that can be turned back into glucose when we haven't eaten for a while. But most of the sugary stuff is distributed right away. Glucose levels in the blood shoot up, and the pancreas gets busy, pumping out the insulin that cells throughout the body need in order to take in glucose and use it for energy.
Oversupply the metabolic pathway for fructose with this sugar, and the liver ends up churning out triglycerides – fat that circulates in the blood.
Post-meal glucose and insulin spikes are perfectly normal and entirely unavoidable. But if they're too big, or come too often, they're harmful. Canadian researchers devised the glycaemic index (GI) to make it easier to compare how different food affects blood sugar levels: the higher the GI number, the bigger the increase in blood sugar.
A number of studies have found that people who eat a lot of high-GI foods - cookies, sweets, bread made with refined flour, and potatoes - have higher rates of diabetes and heart disease.
Specialised metabolism
Pretty much all of the body's cells come equipped with enzymes that allow them to harness glucose. But the enzyme that metabolises fructose, called fructokinase, is found exclusively in liver cells. So although fructose is involved in glucose metabolism indirectly, fructose metabolism is pretty specialised. As a result, if you eat fructose, your blood glucose and insulin levels stay fairly level.
If, as the GI-index research indicates, glucose and insulin increases are a problem, then replacing other sugars in your diet with fructose looks like it might be a solution.
But, alas, it's more complicated than that. For all the mischief that glucose and insulin cause, they do trigger some helpful hormonal changes. Levels of leptin, the hormone that gives us that "full" feeling, go up when insulin surges, and levels of ghrelin, the "hunger hormone," go down.There's fairly good evidence that fructose has just the opposite effect, reducing leptin, so we don't necessarily feel full after a fructose-filled meal, and not lowering ghrelin as much as glucose does, so we stay hungry. For this reason, some experts see high-fructose diets as contributing to overeating.
And there's another problem: Oversupply the metabolic pathway for fructose with this sugar, and the liver ends up churning out triglycerides - fat that circulates in the blood. The same is true of glucose and its metabolic pathway, but a larger amount of glucose is required to cause an oversupply.
Fructose is a naturally occurring sugar. You'll find it in honey, vegetables (in small amounts), and, of course, fruit. Not all the sugar in fruit is fructose, which is one of the reasons - lack of fibre is another - that some fruit, such as watermelon, have a high glycaemic index.
The great American weight problem and the sweetening of the food supply with the suspect syrup happened at about the same time.
But most people's intake of fructose from fruit and vegetables is dwarfed by what they get from sucrose - better known as table sugar, or just sugar - and high-fructose corn syrup. Sucrose is a two-sugar molecule (a disaccharide) consisting of fructose and glucose. High-fructose corn syrup is corn syrup that has been processed to increase the fructose level, which makes it taste sweeter.
The most common variety is 55% fructose and 45% glucose. In the US, high-fructose corn syrup has replaced sucrose as a sweetener, especially in soft drinks, but in many other types of food too.
Experts debate how responsible high-fructose corn syrup is for the American obesity epidemic and the soaring type 2 diabetes rate. Those who see a connection note that the great American weight problem and the sweetening of the food supply with the suspect syrup happened at about the same time. They also point to fructose metabolism and its triglyceride output.
Skeptics counter with several arguments. Sucrose and high-fructose corn syrup contain about the same amount of fructose and glucose (a 50-50 split versus a 55-45 one), so it's questionable whether the metabolic effects are that different. Further, many of the damning metabolic studies have used all-fructose solutions, not high-fructose corn syrup. And they add, the real problem is all the nutritionally empty, added sugar in our diets, not any particular form of that sugar.
Watch the syrup
Where does this leave us? Certainly no one should stop eating fruit out of some misguided fear of fructose. Most varieties of fruit are brimming with nutritional virtue - vitamins, minerals, fibre - and have relatively little fructose and other sugar.
Is high-fructose corn syrup especially harmful? At this point, the case against food and soft drinks sweetened with the stuff is pretty persuasive.
**********************************************
Ok, so then I wondered, well how much Fructose is too much????
*****************************************************
Next article: Fructose (I did not copy the whole article below - just the highlights I felt were important to this discussion) http://talktomejohnnie.com/diet/fructose
FRUCTOSE
By John | Published: August 22, 2010
John – I was at your most recent CrossFit Football certification and during the nutrition talk you cautioned us about over-consumption of fruit and more specifically fructose. Can you go into more detail on why I should be weary of fructose ?
Consuming large amounts of sugar, especially fructose, has pronounced negative effects on the body. Chronic overconsumption of fructose has been shown to lead the way to obesity, metabolic derangement, diabetes and cancer.
What about fructose?
Fructose can only be metabolized in the liver. The liver can process a decent amount of glucose but it gets full quickly. And while fructose can be used to replenish liver glycogen it does not suppress ghrelin and does not stimulate insulin or leptin secretion. Ghrelin is the hormone that regulates hunger.
So what happens when the liver gets bombarded with fructose and the liver has full glycogen stores?
Once the liver is full of glycogen, the body reacts and starts making fats (palmitic acid) from the fructose and sending them off into the bloodstream as triglycerides.
Excessive amounts of carbohydrates are converted to palmitic acid, a saturated fatty acid; this fatty acid is synthesized into triglycerides and sent into the blood stream. Once palmitic acid hits the blood stream it heads over to the CNS where is does its best to disrupt insulin and leptin signaling.
Everyone is familiar with insulin but what does Leptin do?
Lepin regulates energy intake (appetite) and expenditure. Leptin resistance prevents the brain from detecting its energy reserves or signals of satiety. This results in overeating and changes the body fat mass, which leads to weight gain.
Once liver insulin resistance sets in, the liver becomes a garbage dump releasing glucose into the bloodstream regardless of the levels. The resulting high levels of blood glucose, insulin and triglycerides will stimulate adipocytes (fat cells) to store fat and muscle cells to store glucose as glycogen.
Glucose and fructose become toxic to the cells in high concentrations. Glucose toxicity contributes to the development of diabetes. Long-term effects of glucose toxicity leave individuals with decreased insulin sensitivity. And diabetes develops when insulin production is inadequate for a given level of insulin sensitivity.
How much fructose can the body handle before we start running in to problems?
From my understanding, we can safely process about 50 grams of fructose before things become problematic. That is a pretty low dose of fructose so use the chart below to gauge how much fructose you can consume. We know that problems with fructose are dose-dependent and time-dependent.
There is a table of fruits and sugars on The Paleo Diet listing quantities of sugars in fruits, sweeteners and candies. You can get an idea of which fruits/sugars/foods are highest in fructose, glucose and sucrose. From this you can start to understand where fructose is found in large amounts. Dried fruit is one of the highest on the list (one of the reason we discontinued the sale of beef jerky and dried fruit packs from Paleo Brands), high fructose corn syrup, mangos, apples, oranges, grapes and the amount of fructose in the juice version of these fruits is staggering.
Third: Ok, and lastly here is the table mentioned in the above second article. http://www.thepaleodiet.com/nutritional_tools/fruits_table.html
Ok, I can't copy and paste the table without being a mess so copy and paste the link and take a look, ok?
**************************
So what do you guys think? Should I add sugars to my daily diary and try to keep Fructose under 50 grams a day? Again, sorry if this isn't from scientific journals. Please don't make fun of me if I have become THAT person who believes everything they read on the internet. I mean, come on, if it's on the internet it MUST be true, right (please note sarcasm).
Just would like some thoughts on this, do you think this is true or false? Thanks everyone!
0
Replies
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Yes, I have been saying this on this site for well over a year now.
Fruit is good for us in small quantities, such as eating it for a dessert.0 -
I think it depends on what you're comparing it to.
Yes, when you compare a banana to a celery stalk, it looks pretty bad. It's high in sugar.
Compare that same banana to a cupcake, and you're looking pretty good.
If we're subbing in fruit for sweets, I think we come out ahead in the end. Yes, there are ways to be perfect, but that's no fun, right?0 -
I agree about eating fruits as a snack. I was recently on the weight watchers program..right before they converted to the "fruits and veggies=0 points now, so eat as much as you want!" plan. A fellow member knew the change was coming so he converted to the new plan early. said he ate fruit for every meal and snack all week. annnnd he gained 5 pounds that week- when before that he had been losing steadily.0
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Moderation is key.
Excessive Exercise, eating, Not Eating, eating only this and not that (No/Low Carb any one?) and so on all come with trade offs.
They may provide some short term benefits but do IT
long enough and it will come back to haunt you with less than desirable results.0 -
0
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Ok, some more info I think may be helpful:
http://figureathlete.t-nation.com/free_online_article/diet_and_nutrition/the_low_fructose_diet
Why Does Fructose Cause Fat-Gain?
Fructose and fructose-containing foods will usually make your meals taste better, so you end up eating much more than necessary. They also fail to make you feel satisfied after you eat them, due to inadequate stimulation of leptin and ghrelin, the two satiety hormones. (6)
There is also evidence that fructose slows your metabolism: kids who drink sodas and fruit juices (both are rich in HFCS and fructose) are fatter than those who don't drink them, but who eat the same amount of calories. (7)
So, What Kinds of Fruits and Vegetables Can I Eat and Not Get Fat?
Although fruit does contain some fructose, it's not the only sugar that it contains. Fruit is beneficial for you because it's the best natural source of antioxidants that help you fight free-radicals, a major cause of aging and muscle damage. It's also an important source of fiber.
Your best bet is to choose fruits that are low in fructose, and only eat the higher fructose fruits in the morning, when your liver glycogen levels are low. At this time, your liver can use or store the fructose without converting it to fat.
The following fruits are highest in fructose (per typical serving size)*. They contain more than 4 grams of fructose per serving.
Stay away from these outside of an occasional breakfast:
• apple
• banana
• cherries (1 Cup)
• grapes (1 Cup)
• mango
• melon (2 wedges)
• orange
• pear
• pineapple (2 rings)
• watermelon (1 large slice)
These fruits are lowest in fructose; they contain less than 4 grams of fructose per serving.
You can eat these with less restriction:
• apricot
• avocado (1/3 medium; yes, it's a fruit)
• blackberries (1/2 cup)
• figs
• grapefruit (1/2 medium)
• papaya
• peach
• plum
• raspberries (1/2 cup)
• strawberries (1/2 cup)
• tomato (yes, also a fruit)
*Note, these values were calculated by adding all of the fructose plus have of the sucrose per typical serving size (i.e., a typical apple weighs 120 grams)
Vegetables are much lower in fructose than fruits. The highest fructose-containing vegetable are corn and sweet potatoes, and they only have roughly 1.2 grams of fructose per serving. If you're really trying to keep this sugar low, also avoid white potatoes and green peas.
Bottom Line:
Fructose may be one of the reasons your body is not dropping the stubborn body fat you've been fighting for weeks, or even months. Before you start avoiding the produce section of the grocery store, start scanning the labels of some of your most frequently consumed foods.
Does your salad dressing contain HFCS? Do you douse your morning eggs with HFCS-laden ketchup? Or maybe you're known to eat "all-natural" products made with honey?
Once you've eliminated these major fructose-suspects, turn to your fruit intake. Don't eliminate it completely because some fruit will aid your overall health and beauty by fighting free-radical-induced aging and muscle damage. Just choose fruits lower in fructose.
Apples may keep the doctor away, but with their high fructose content, they'll keep your sexiest bikini just as out of sight.
About the Author:
Cassandra Forsythe is a Ph.D. candidate at the University of Connecticut studying exercise science and nutrition. She received her M.S. in Human Nutrition and Metabolism and her B.S. in Nutrition and Food Science from the University of Alberta in Edmonton, Canada. She is certified as a Strength and Conditioning Specialist (CSCS) from the National Strength and Conditioning Association (NSCA), and is a Certified Sports Nutritionist (CISSN) through the International Society of Sports Nutrition (ISSN).0 -
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