Is fructose a problem?

[Tony]

“In a study of 143 patients fructose malabsorption was found in 45.8% of patients.”

A dietitians summary of fructose malabsorption:
http://www.ledanutrition.com/pdf/Fru...Fact_Sheet.pdf

"Fructose malabsorption is a condition where the small intestine is impaired in its ability to absorb fructose (a naturally occurring sugar).
When fructose is not absorbed properly in the small intestine, it can travel through to the large intestine where bacterial fermentation can cause symptoms of irritable bowel syndrome."

..."People with fructose malabsorption find wheat, not gluten, is a problem food when consumed in large amounts, and so can generally eat rye, barley and oats.

People feeling better on a wheat-free diet should be investigated for coeliac
disease firstly, and then have investigations for fructose malabsorption. Some
people can have both coeliac disease and fructose malabsorption. Fructose does not cause damage to the small intestine like gluten does in people with coeliac disease."
Some good links with further info:

Research: http://sacfs.asn.au/download/SueShepherd_sarticle.pdf

http://www.healthsystem.virginia.ed...ebsearch.cfm?lookinfor=fructose&s=information

http://www.ncbi.nlm.nih.gov/pubmed/...nel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

When I found that I had fructose malabsorption this is some advice the dietitian gave:

Eat a low fructose and fructan diet but it isn’t necessary to cut out all foods that may be slightly high in fructose. It’s more about the balance of the meal.

Cut out wheat, apples, pears, fruit juice, dried fruit, watermelon, mango, fig, persimmon, pawpaw, quince and others mentioned in this article: http://www.ledanutrition.com/pdf/Fructose_Malabsorption_Summary_Fact_Sheet.pdf

Also off the menu are onions, spring onions, green and yellow beans, leeks, artichoke, asparagus and chicory (witlof, endive, radiccio), coconut cream, coconut milk, honey, caro and tomato paste.

OK to eat are bananas, kiwi fruit, oranges, mandarins, pineapple, apricot, peach, berries, honey dew, grapes etc but it’s better to eat fruit after or with something else.

Also to not eat too many fruits per day. (A rough guide is no more than 2-3 “safe” fruits per day, but I prefer 1-2.)

 

[alice1]

Fructose(in products labelled as frustose) is actually the worst of sugars out there.It is a sugar that will by pass and shove its way around and through all the others to get to cancer cells.
Because of the way it has been processed..high temps..it's up there with corn syup.Many people are using Agave now because it comes from a plant source.
The only way to achieve the sweetness from the shrub is to boil the leaves at such high temps that it burns any of the nutrient and has turned it to fructose .
We tend to think if it says fructose it must be fine..it's not. You can google the harms of frutose and read what is now known.
Eating the fruits you're allowed is the best thing.
Good luck.

 

[cigana]

Hi Tony,

The link you posted for the factsheet appears to be broken...

Do you know much about what fructose absorption really means? I mean, if you have frictose malabsorption, can't we also have general-carbohydrate malabsorption, or are there separate tests? I'm wondering if our guts are damaged in such a way that we have lots of problems and since tests only show up individual problems we tend to focus on those only (and hence miss the bigger picture - that we might be intolerant to lots of things). That's why I prefer the elemental diet approach, because it doesn't contain anything that needs to be digested and gives the system a complete break.

Cheers,

Cig

 

[Glynis Steele]

Hi Cig,

Here is an extract from an article (dla- as usual) where the writer explains how a bacterial overgrowth can damage the gut.

Fructose can be monosaccharides or disaccharides (a fructose and glucose molecule). Complex starches are also mentioned.

BW

Glynis

Migration of bacteria up the small intestine so that they can
encounter sugars before they are completely absorbed. Bacteria may
migrate into, or persist in the lumen of the small intestine for two
major reasons. First there may be an anatomical lesion such as a
short bowel or a blind loop which provides the opportunity for
bacteria to colonize a location prior to complete absorption of
sugar. Second, pharmacologic agents or disease states may slow
bowel motility to a sufficient degree so that bacteria may migrate
into, and multiply in the lumen of the small intestine, thereby
accentuating the production and absorption of organic acids

Conditions favoring over-production of organic acids in the GI
tract.
(a) Supply of substrate to the bacteria. There is a clinical
observation that in the suitable host, D-lactic acid accumulation
may be exacerbated by feeding. When there is bacterial
overgrowth in the small intestine, the concentration of brushborder
enzymes may decrease. Thus ingested disaccharides
and complex carbohydrates may not be hydrolyzed at an adequate
rate because of low luminal disaccharidase activity. These sugars
may then be fermented by bacteria which have colonized the small
intestine or may be delivered to the colon where they can undergo
anaerobic fermentation by colonic bacteria.

 

[slayadragon]

I'm not finding these two articles.

http://www.healthsystem.virginia.edu...ettArticle.pdf

http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum

Tony, might you recheck the links?

Thanks for providing this info. It's really interesting.

Best, Lisa

 

[cigana]

Hi Glynis,

Cheers for the (DLA-) info. Are they basically saying SIBO can occur?

I didn't realise fructose could be a monosaccharide or a disaccharide - so there are more than one type of fructose??

Cig

 

[Glynis Steele]

Hi Cig,

Sorry, I think I worded it incorrectly. Fructose is a monosaccharide. It can be bound to glucose (sucrose), which is then a disaccharide. Yes, I think the article is saying if you have a short bowel, or blind loop, SIBO can occur. Also if you are taking certain medications, or have some disease, the motility of the bowel can be slowed, and this would result in SIBO. Normally peristalsis would stop bacteria from migrating to the small bowel. Jasmine takes medication as she has slow gut motility, and vomits without it.

Hope you are keeping well.

Glynis

 

[Sean]

Glucose is not sucrose. Sucrose is fructose and glucose bound together, and the body needs to separate them before they can be used.

Glucose also comes in two forms - stereoisomers - a left and a right handed version. The right handed version is dextrose, which is the main sugar the body uses. The left handed version is biologically inactive.

Fructose is not so good for the body, as it can only be processed by the liver. Dextrose can be used directly by virtually all cells.

 

[Tony]

Hi Lisa, try these links: http://www.healthsystem.virginia.ed...ebsearch.cfm?lookinfor=fructose&s=information Second reference on the page.

Dietary triggers of abdominal symptoms in patients with irritable bowel syndrome: randomized placebo-controlled evidence:
http://www.ncbi.nlm.nih.gov/pubmed/...nel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Hi Cig, the link works ok for me but I've posted it below for you. I don't know any more about fruc mal than what's here. But some will have trouble with a high carb diet and sugars as well. I know I do. If I remember correctly the d-lactate paper by Sheedy and De Meirleir recommended a low sugar/ carbohydrate diet.

Here's the text for the factsheet. I think it was written some years ago, prior to the research papers mentioned. There are a couple of others done by Shepherd, Barrett and Gibson alone or together on pubmed.

Fructose Malabsorption Summary Fact Sheet

By Sue Shepherd, Accredited Practising Dietitian.
B.App. Sci (Health Promotion), M. Nut & Diet, PhD Researcher
www.coeliac.com.au

Fructose malabsorption is a condition where the small intestine is impaired in its
ability to absorb fructose (a naturally occurring sugar).

When fructose is not absorbed properly in the small intestine, it can travel
through to the large intestine where bacterial fermentation can cause symptoms
of irritable bowel syndrome. These include bloating, wind, pain, nausea,
diarrhoea and/or constipation.

Although fructose is present in one form or another in virtually every fruit, and in
many vegetables and grains, not every food source of fructose needs to be
avoided by people with fructose malabsorption.

The most commonly consumed “problem” foods are:
Fruits: Apple, pear, mango, watermelon, quince, paw paw, lychee, guava,
pomegranate.

In excess, the following are problematic: dried fruit, fruit juice, tomato paste.
Vegetables: onion, spring onion, leek, asparagus, artichoke, Jerusalem artichoke,
witlof, chicory, radicchio, endive and dandelion greens.

Others: honey, coconut cream and large quantities of wheat. Fructose, fruit juice
sweeteners (apple juice concentrate, pear pastes) and high fructose corn syrups
are ingredients that are concentrated in fructose and are a problem in large
amounts.
Consuming large quantities of even “safe” fruits can cause symptoms.

People with fructose malabsorption find wheat, not gluten, is a problem food
when consumed in large amounts, and so can generally eat rye, barley and oats.

People feeling better on a wheat-free diet should be investigated for coeliac
disease firstly, and then have investigations for fructose malabsorption. Some
people can have both coeliac disease and fructose malabsorption. Fructose does
not cause damage to the small intestine like gluten does in people with coeliac
disease.

 

[cigana]

Thanks Tony.

I would hazard a guess that the only carbohydrate safe for us is glucose...

Cig

 

[Fejal]

This stuff about fructose being so bad is only true in excess. Fructose raises systolic blood pressure so hypertensives need to be careful. It does this by making the kidneys retain more sodium. In excess it is converted to fat so don't eat a lot of it. However a piece of fruit and a few teaspoons of honey per day isn't going to harm anyone. Also remember that lots of vegetables and grains have a great deal of fructose (wheat, pasta, broccoli, asparague, chocolate, etc).

Soda and prepared foods are the main suspects for a high fructose diet along with the above foods listed.

On the good side, fruit has been shown to help people lose weight. It causes people to eat less glucose and have less insulin produced, helping weight loss.

 

[Tony]

Yes, excess fructose can be a problem. This is stated by the dietitian in the fact sheet info I posted previously. Broccoli does have a higher fructose level than glucose but it's hardly a problem in this area as we don't tend to eat kilo's of the stuff...

For people with fructose malabsorption the idea is to look at the meal overall, not so much as separate items but leaving out "problem" foods. Not everyone will have the same level of problem even within this group. So a bit of broccoli or a piece of fruit is generally fine. One of the tips from the gastroenterologist and dietitans study is to eat fruit with foods such as meat, fish, eggs, beans or nuts.

There's more info in the research paper on ratios of fructose to glucose in foods for those who'd like to read it.

 

[Snow Leopard]

This stuff about fructose being so bad is only true in excess.

'Excess' differes from person to person. If you review the literature, a normal person can handle around 25-50 g, whereas someone who has malsorption may only be able to digest 10 g or less. Although the amount that can be absorbed depends on the ratios with other carbohydrates.

I recommend hydrogen breath testing - my fructose test was borderline normal, whereas my lactose test was abnormal with 'high hydrogen background'.

 

[Fejal]

I don't trust dietician's advice. It's usually wrong.
Case in point, mixing foods is pointless and harmful. Fructose doesn't cause an insulin surge so there's no benefit to slowing digestion with fiber or fat.
The main thing is to be aware of how the body is handling the fructose it is given so you don't overeat. Also don't flavor food as things that it isn't. For example, giving foods low in a nutrient that taste.

Most people aren't aware of the high amount of fructose in the foods I listed so they need to be taken seriously.

Excess fructose that isn't absorbed is transformed into fat by intestinal bacteria and absorbed in the colon.

Fructose intolerance is largely an issue of exposure. Chronic overexposure causes resistance to transport mechanisms. When the balance is restored transport capacity increases and the body adapts to meet its needs. So the belief that fructose intolerance is a predetermined genetic disease with no variability based on exposure is false.

 

[Tony]

Another study people may be interested in:

Clinical Ramifications of Malabsorption of Fructose and Other Short-chain Carbohydrates

Cheers...

 

[Athene]

I don't trust dietician's advice. It's usually wrong.
Case in point, mixing foods is pointless and harmful. Fructose doesn't cause an insulin surge so there's no benefit to slowing digestion with fiber or fat.
The main thing is to be aware of how the body is handling the fructose it is given so you don't overeat. Also don't flavor food as things that it isn't. For example, giving foods low in a nutrient that taste.

Most people aren't aware of the high amount of fructose in the foods I listed so they need to be taken seriously.

Excess fructose that isn't absorbed is transformed into fat by intestinal bacteria and absorbed in the colon.

Fructose intolerance is largely an issue of exposure. Chronic overexposure causes resistance to transport mechanisms. When the balance is restored transport capacity increases and the body adapts to meet its needs. So the belief that fructose intolerance is a predetermined genetic disease with no variability based on exposure is false.

Fejal, I don't want to seem rude, but this is twaddle.

Excess fructose that itn't absorbed is NOT turned into fat!!!! And it is not absorbed in the Colon - frustose malabsorption means that you cannot absorb fructose.
The frustose is used and fermented by bacteria in the gut, producing hydrogen which results in a painful amount of gas in the intestine. The remainder, like all sugars, has an osmotic effect and draws water into the intestine, resulting in diarrhoea. When you combine diarrhhoea with gas, you end up with the type of farts that mean you have to go off and change your underwear. This is the reason why frustose malabsorption is such a misery, and why people who have this problem KNOW that they have a real problem: most people round here are too polite to inform you of this fact, but I believe in telling it straight!!!

The food mixing that Tony described helps simply because it reduces the fermentation and therefore the pain. It also helps you to eat less vegetables. Most peope can healthily fill up on veg, but when you have fructose malabsorption this is not an option, so you have to fill your stomach with something else.

Any comments about insulin is irrelevant to people with fructose malabsorption. If you do not absorb fructose, it does not enter your bloodstream so there is no need for insulin at all. The problem exists in the gut.

There is no such thing as "resistance to transport mechanisms". The transport factor for fructose is called GLUT-5 and it is made by the liver and released into the intestine in restricted amounts. If you make it, it works - there is no type of fructose that can resist it!! It locks onto the fructose molecules and "escorts" them into the bloodstream. The problem with fructose malabsorption is that the liver makes very little, or no, GLUT-5.

The reason nobody can absorb more than a limited amount of fructose - not more than 50g in a go for anyone - is because the liver limits the amount of GLUT-5 it produces to create a deliberate bottleneck. As soon as fructose enters the bloodstream it becomes toxic, lethally so, and the liver has to convert it to glucose as a matter of urgency. It can only work so fast, so it has to make sure the bloodstream does not get poisoned by an excess of fructose.

If you are in any doubt about the fact that fructose is lethally poisonous, then try Googling a genetic disorder called Hereditary Frustose Intolerance. People with this illness can absorb fructose, but they cannot convert it into glucose. If they eat just one tiny piece of fruit, they die. Children with this horrific illness have to live without ever eating a single piece of fruit or vegetable.

The best source of help on this that I have found is a fructose malabsorption forum
http://groups.yahoo.com/group/fructose_malabsorption_australia/
Here you can download a spreadsheet of the precise fructose content of each fruit or vegetable and you can also ask other forum members about any foods that you do not find there.

 

[Fejal]

Fejal, I don't want to seem rude, but this is twaddle.

Excess fructose that itn't absorbed is NOT turned into fat!!!! And it is not absorbed in the Colon - frustose malabsorption means that you cannot absorb fructose.

Twaddle, that's cute. You’re wrong on the major points, but part of it is my fault for not providing enough information. You are correct that normally people can't metabolize fructose into fat, if you're skinny, however according to this article and referenced study the bacteria Firmicutes, common in fat people, does digest carbohydrates into absorbable fatty acids.

http://www.newsweek.com/2010/07/06/don-t-just-blame-calories.html

The bacteria-made-me-fat idea has been gathering steam since 2006. In that year, Jeffrey Gordon of Washington University and colleagues reported in a paper in Nature that obese mice and slim mice have different populations of gut bacteria. Crucially, they showed that the bacteria caused obesity, rather than obesity producing a specific mix of bacteria. When the scientists plucked bacteria called Firmicutes from obese mice, then put them in the bacteria-free guts of mice raised in a sterile environment, the latter bulked up within 10 to 14 days—even though they ate less.
Why? Firmicutes, it seems, are more adept at liberating calories from food than are bacteria from the other common lineage, Bacteroidetes. Firmicutes can digest complex sugars that neither the mice’s own enzymes nor Bacteroidetes can, breaking them into simple sugars and fatty acids that the mice’s intestines then absorb and turn into more mouse.

>There is no such thing as "resistance to transport mechanisms". The transport factor for fructose is called GLUT-5 and it is made by the liver and released into the intestine in restricted amounts. If you make it, it works - there is no type of fructose that can resist it!! It locks onto the fructose molecules and "escorts" them into the bloodstream. The problem with fructose malabsorption is that the liver makes very little, or no, GLUT-5.

How do you know that GLUT-5 resistance is impossible if excess fructose is chronically eaten? I find your strong objection very rash in light of that fact that you didn't even seem to do any research before commenting. It reminds me of the disproven theory that lack of insulin causes diabetes. Resistance happens with the other hormones, so it would be logical that it could happen here especially given how much fructose is present in modern diets. Excess fructose = downregulation of transporters.

It took all of three minutes to find a study to contradict your opinion.

As the rats aged and become more obese and insulin-resistant, adipocyte GLUT5 surface density (12-fold) and fructose transport (10-fold) and utilisation rates (threefold) fell markedly. The GLUT5 loss was more dramatic in adipocytes from obese animals, which developed a more marked insulin resistance than lean counterparts. The decline of GLUT5 levels in adipocytes from older, obese animals was not a generalised effect, and was not observed in kidney, nor was this expression pattern shared by the alpha1 subunit of the Na+/K+ ATPase. Our findings suggest that plasma membrane GLUT5 levels and thus fructose utilisation rates in adipocytes are dependent upon cellular insulin sensitivity, inferring a possible role for GLUT5 in the elevated circulating fructose observed during diabetes, and associated pathological complications.(Litherland, GJ. Fructose transport and metabolism in adipose tissue of Zucker rats: diminished GLUT5 activity during obesity and insulin resistance. Mol Cell Biochem. 2004 Jun;261(1-2):23-33.)

I'm quoting it here because it shows that the GLUT5 transporters do get downregulated. However I do disagree with Litherland's assumptoin that insulin, a different hexose sugar, was modulating GLUT5, a pentose sugar. It doesn't make sense because the transport systems for insulin and fructose are different. I can see why he did it because the insulin resistance develops simultaneously. A better explanation is that that GLUT5 is downregulated due to high exposure.

>The reason nobody can absorb more than a limited amount of fructose - not more than 50g in a go for anyone - is because the liver limits the amount of GLUT-5 it produces to create a deliberate bottleneck. As soon as fructose enters the bloodstream it becomes toxic, lethally so, and the liver has to convert it to glucose as a matter of urgency. It can only work so fast, so it has to make sure the bloodstream does not get poisoned by an excess of fructose.

I don't think that it's fair to characterize fructose as a poison. Many required nutrients are poisons if overdosed; after all that's why we have livers-to detoxify things. Many high fructose foods have exceptional health benefits. For example, broccoli and broccoli sprouts for preventing cancer, blueberry antioxidants, and cranberries for curing urinary tract infections, etc. Fructose has been proven to help people lose more weight than abstainers. However, I am going to go out on a limb here and argue that humans have a specific appetite for fructose because it is so useful. It is the preferred energy source for replenishing liver glycogen and is very useful between meals because it spares glucose by yielding more energy units per molecule with no insulin release. You save 2 NADH per unit of fructose burned compared to glucose. The big problem with it is overdose because people don't eat by appetite but rather by stomach fullness and impulse. If one knows how to read appetite it is very easy to avoid this.

 

[Athene]

Hi Fejal!

Your study about the rats is not about transport factor resistance at all. It is about the reduction in production of GLUT5. The body lowering production of glut 5 is not the same as resistance to glut 5! The body cannot develop resistance to GLUT5, because GLUT 5 does not act upon body tissues in either rats or humans, it acts upon fructose.

Second, the reason broccoli and the other foods you list is good for us is not because it contains fructose, but because it contains a large range of useful nutrients.

The link that you provided led me to an advertisemend for BASF rather than an article. Your point that digested carbohydrates are metabolised as fats is kind of correct, in that excess carbs are stored as fat. This is, of course, the carbs that are absorbed into the blood stream.
This thread is not about carbs in general, though, it is about fructose in particular. And specifically, about NOT BEING ABLE TO ABSORB FRUCTOSE. If you cannot absorb fructose it is not metabolised into anything, it stays in the gut, that is the definition of not absorbing something!!!

 

[Fejal]

Athene,

Good point, thanks for clarifying. I found a second transporter named GLUT7 that carries both glucose and fructose.

>A closely related protein of GLUT5 is GLUT7, bearing 53% identity. It is a high-affinity transporter for glucose and fructose and is mainly expressed in the brush-border membrane of the small intestine and in the colon (11).

http://ajpendo.physiology.org/cgi/content/full/295/2/E225
source 11. Li Q, Manolescu A, Ritzel M, Yao S, Slugoski M, Young JD, Chen XZ, Cheeseman CI. Cloning and functional characterization of the human GLUT7 isoform SLC2A7 from the small intestine. Am J Physiol Gastrointest Liver Physiol 287: G236–G242, 2004

GLUT5 doesn't transport in the blood, only the intestinal border so it isn't used up, just rate limited. The control mechanisms are in other places:

• Stress causes release of glucocorticoids which increases absorption of fructose by GLUT5. (Thiesen A. Dig Dis Sci. 2003 Nov;48(11):2196-206. Pmid 14705828)
• Saturated fat also increases fructose absorption by GLUT5. (need reference).
• Adults upregulate in sperm.
• Upregulated in adipocytes if hypoxic. (Wood. PMID 17658463)


More information:

GLUT5 is upregulated in type 2 diabetes.

So the original author was right, it depends on glucose availability. A low carb diet upregulates fructose transport. Interesting.

 

[Glynis Steele]

Whilst this is not technical, I thought it might be of interest here.

http://www.dailymail.co.uk/femail/article-1325453/Everything-thought-knew-food-WRONG.html

BW

Glynis