5

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How much fructose is too much fructose?

Answered on August 19, 2014
Created February 18, 2011 at 11:28 PM

Lately I've been looking at how much fructose I eat daily, all of which comes from fruits and vegetables. I've decided to cut back on fruit consumption for a bit. But I am also looking critically towards the vegetables and tomatoes. I like tomatoes but they are technically a fruit (although legally a vegetable) and are considered 'high fructose' by many. I am reading that 1 cup of fresh chopped tomato has 2.5 grams of fructose. And onions have 2.6 grams of fructose per cup (not sure if this is pre or post cooking) Is this considered a lot? What is a good cutoff for amount of grams of fructose per day? I have heard some suggest 4 grams per day as a good number to stay under.

I know lifestyle and goals are going to influence any recommendations. I am curious both from a general scientific standpoint as well as from a personal one. My main goal right now is health and to continue feeling healthy. Paleo (plus magnesium pills) has made me feel probably the healthiest I have ever felt. However, I wouldn't mind losing a few more pounds and so I am experimenting with different macronutrient profiles to see what feels best. On the flipside I feel rather happy now and most of my experimentation is more due to curiosity than anything else. Activitywise, I spend a large portion of each workday walking around. I also like to hike in the mountains about once per week. And erratically I go to the gym and lift weights. So I would say I lead a moderately active lifestyle.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 08, 2013
at 08:07 AM

tbh i think mongolians are almost not like asians at all - physically or metabolically. we're more caucasoid, my build and musculature is more like that of a Kazak or Russian, and I have blue eyes btw.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 08, 2013
at 08:06 AM

yes im lactose tolerant. mongolian nomad genes babyyy!!

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 08, 2013
at 08:05 AM

yeah lots of meats (no fructose), some dairy, eggs, very little veggies and a good amount of white potato/white rice (almost fructose free). no diet sodas, just herbal tea/coffee with cream. its actually what i'd prefer to eat anyways. i like meat + clean starch

D33a8d5f095a8532ddf7a0d6c27bfe63

(578)

on April 07, 2013
at 11:13 AM

I don't think you need to stay away from fructose-containing veggies. It's dose-dependent so if you're doing, say, under 20g of fructose per day, I think that's sufficient. Plus there could be some hormetic effect of fructose intake. Like most things, I tend to think it's the J curve that determines optimal vs. suboptimal.

D33a8d5f095a8532ddf7a0d6c27bfe63

(578)

on April 07, 2013
at 10:03 AM

That's interesting. So I assume you're lactose-tolerant, unlike most Asians? What do you normally eat with rice, then? Just meats? Any tubers at all?

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 07, 2013
at 07:13 AM

i totally agree with you Travis, 20g of fructose a day kept me fat (30-40lbs overweight). mind you, i'm mongolian and a bit of an extreme metabolic case

3fe2bf1367970868757ddf7ed7c62531

(817)

on January 10, 2013
at 08:26 PM

I started taking magnesium oil via the skin. About one teaspoon rubbed on my stomach before bed. Best sleep ever, most vivid dreams that I can remember all day! I also take some citrate sometimes too.. Starting to take magnesium has been one of the best things ever!

742ff8ba4ff55e84593ede14ac1c3cab

(3536)

on January 08, 2013
at 01:57 AM

I had to downvote this answer. I can't believe how stupid I sound.

35cebc412367f53cbc1cb804d7a72375

(10)

on January 08, 2013
at 12:04 AM

p.s. Researchers have also discovered that the bodies of some (maybe all) obese people can convert blood glucose into fructose! So keeping total carbs down (in order to keep blood sugar down) is important too.

Ce2968ab71119c736ba9d83841c5718a

on September 13, 2012
at 02:18 PM

"However, we all came from the few folks in the tropics and Africa. Have we lost the ability to metabolize fructose in comparison to Africans? " <-- That's not so hard to imagine, the did lose the sun protecting skin pigments...

100fd85230060e754fc13394eee6d6f1

(18706)

on February 19, 2011
at 03:07 PM

Yeah, I see what you're saying. I definitely wouldn't keep it up just for theory's sake -- I enjoy vegetables too much. Regarding the calorie difference, I think it's possible that a change in hormonal response could have a more dramatic effect, even with only a small caloric change.

0adda19045a3641edac0008364b91110

(1146)

on February 19, 2011
at 02:45 PM

@ Eva, I have never had weight problems, even when my diet consisted of 500 grams of carbs, quite the opposite in fact (can't gain), so I can't say much on that subject. @ mathew... I will in no way avoid onions and tomatoes, I just won't eat as much as I was eating.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on February 19, 2011
at 11:58 AM

Dexter in the article you link says - "After drinking either a fructose- or glucose-sweetened beverage that made up 25 percent of their daily calories for 12 weeks..." No one thinks drinking 25% of you calories as refined fructose is good. If you could find a study showing that 5% of calories from fructose in whole foods causes any of those negative effects I would pay more attention.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on February 19, 2011
at 11:48 AM

Please don't avoid onions or tomatoes due to the really tiny amounts of fructose they contain.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 10:42 AM

It might take a while though-- at 3500 kcal per pound of fat, with usual daily caloric changes of (-100 kcal) producing weight change, it would take 210 days to lose six pounds. Introducing any other changes during that seven month period would mitigate the results.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 10:39 AM

True, whether the effects are due to the nutrient change or due to placebo effects or other correlates, it's still weight loss.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 08:44 AM

Isn't Australia pretty sparse with regards to vegetation, compared to other equatorial geographies? Anyways...when I had previously asked a question questioning paleo egg availability, everyone was like "dude, they would have totally known where all the eggs were and eaten them, and some birds lay all the time". Point being, fruit might be held to a bit of a double standard here. Hunting animals is very difficult with crude weapons and requires not just walking but treks. Finding fruit trees and berry bushes is relatively easy. It's even easier than digging up tubers.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 08:21 AM

If you cut out tomatoes and onions, you better also cut carrots, potatoes, etc etc. They all contain quite a bit more fructose than the teeny amount in tomatoes and onions. What I'm really trying to say is that some sort of fructose bug seems to be infecting paleohacks, and it seems overblown unless I'm missing something. Not sure what caused the bug to start, maybe Dr. Harris's carb post. But I'd suspect he might consider this to be a wee bit alarmist?

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 06:23 AM

Kamal, berries are something that often take time to harvest. I remember once when someone interviewed an Australian aborigine on the subject of survival who explained that although he knew berries were growing some distance away, the energy required to walk so far would be greater than the sustenance gained from a few berries.I don't think we can say for sure what fruit the ancient paleos ate or did not eat. And it probably varied quite a bit depending on location. Even in the jungle you may have to walk a long way to get to an edible fruit tree and it doesn't fruit all year long either.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 06:14 AM

Actually, I think it's gonna be simple. When I eat starch but not fructose, either I lose weight (more than a few pounds either way) or I don't. Or I gain. Of course, whatever happens for me does not mean it will happen for another. But if it happens to me, it will probably happen to some others and will be worth keeping in mind as a possibility/option.

Fbbbdf1d0a7d6d5067a106af062c7ce6

(745)

on February 19, 2011
at 04:57 AM

First heard the 50/50 comparison via Mat Lalonde at OPT CCP Nutrition level-1 certification. Looks like Mat wasn't BS'ing (he does, after all, have a PhD in organic chem) http://en.wikipedia.org/wiki/Alcohol_and_cancer#Alcohol_consumption_of_50g_or_more_per_day_increases_risk

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 04:26 AM

It would be hard for berries to be 1/20th as sweet as modern fruit. Take the blueberry for example. One serving of wild blueberries has 3.5 grams of fructose. I'm trying to imagine how bland and microscopic paleo berries would be that have 1/20th of that amount (i.e. 0.18 grams of fructose). Isn't fructose supposed to help in seed spreading for some fruits? That makes me suspicious of the 1/20th figure.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 04:19 AM

Africans' current fruit intake doesn't reflect past intake. Current hunter gatherers have been crowded out geographically and economically. Africa in paleolithic times was more temperate, and fruit was the only way to satisfy your sweet tooth, plus it was not harvested by multinational companies. I bet they ate a ton of fruit! (compared to current Americans, that is)

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 03:56 AM

My bad! Weight change is still pretty hard to ascertain though. Even validated dietary questionares (Food frequency questionares, dietary recalls, food diaries) are contentious in their ability to predict weight change based on nutrient intake. So what I really mean is, be careful about your conclusions.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 03:49 AM

Any diffs in weight or how you felt after you cut down on the tomatoes and onions?

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 03:48 AM

How much fruit do the Africans really eat? The tribes I have seen seem to be eating a lot of meat and tubers and only some fruit. Plus they are more active. More fruit might be fine for those with undamaged metabolisms and/or an active lifestyle, but seems to be more of a prob for those who do not fit that bill. What is good for the healthy is not always what is good for the sick.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 03:44 AM

I know about water weight change, but that is only a few pounds. I look at trends and how my pants fit. I would not be so foolish as to consider only a few pounds on one day to be actual clear weight loss. And if you read my post, I do not work at a desk, nor do I sit during the day much so the advice about a standing desk does not apply.

0bcefaa82dc94f93ce705f86e235f335

(1591)

on February 19, 2011
at 03:35 AM

Do you have a cite, by any chance? Thanks! :)

Ac1e55cf06c2180f4008ff01953d10dd

(3524)

on February 19, 2011
at 03:26 AM

Dexter many wild fruits contains lots of fructose. And we all come from Africa, except for the last 20k years which, according to paleo are of little DNA relevance...

06d21b99c58283ce575e36c4ecd4a458

(9948)

on February 19, 2011
at 03:04 AM

Well, general opinion is that fruit our ancestors ate might be 1/20th as sweet as the fruit we have now....thus a tiny amount of fructose. And many of us migrated north to cold climes where fruit was only available a few months during the summer and fall. And the fructose intake was pretty small. Who knows, but when we inundate our bodies with these modern day super sweet fruit year round, I am pretty sure we do not have the capacity to metabolize that much sugar on a daily basis efficiently...plus add in the modern sweet tooth for raw sugar products...and we have a recipe for disaster.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 02:45 AM

However, we all came from the few folks in the tropics and Africa. Have we lost the ability to metabolize fructose in comparison to Africans?

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 02:31 AM

Have you considered that a weight experiment has low sensitivity to ascertaining dietary change influences? In other words, weight changes rely too much on water weight, hormones de jour, etc. The marginal effects of 0-10 grams of fructose a day would be tiny unless there was some crazy feed-forward lipogensis mechanism (fructose's aren't that crazy if I recall correctly). A much greater calorie burn would be using a standing desk. Standing burns at least 25 calories per hour more than sitting, which amounts to 200 calories per work day!!!

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 02:27 AM

Phoenix-- that was speculation on my part. The reasoning is something like this: Large dose of exogenous AGE in small time window --> overwhelming body's capacity to eliminate AGEs through excretion or protein renewal. Hmmm...maybe isn't as solid as it sounded before.

D30ff86ad2c1f3b43b99aed213bcf461

on February 19, 2011
at 02:18 AM

Thanks for asking this. Considering the tomatoes, squashes/pumpkin, carrots, etc. that are in my diet it would be great to eyeball an optimal zone of acceptable fructose consumption (if there is one).

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 02:17 AM

One thing I plan to experiment with, how much of the prob is fructose and how much is just carbs in general? If it's only fructose, then one should still be able to eat a fair lot of white potato, still avoid much fructose and still not gain weight. But if other carbs are also a prob, then the potato experiment should fail.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 02:06 AM

I have done close to zero carb extremely low fructose in the past so this is not really a new experiment except this time I am paleo instead of just lowcarb. I really don't have an obvious issue with fructose in moderation other than it seems to lead to a few extra pounds, although I am not sure if under 4 grams per day would still have much effect. As for magnesium, I use chelated magnesium glycinate/lysinate from Albion labs. There are actually several vitamin companies that use the albion labs stuff. I started on this one as research suggested it is very good stuff and I like it.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 02:00 AM

Yes! Those yummy little grape tomatoes! I really like those. And onions. For some reason, those two are my favorites, but the onions have to be cooked.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 01:55 AM

"Best trap of my life", nice! The trap here would be if zero carb wasn't noticably doing you good and you wanted carbs, but theoretical benefits down the road changed your habits. So unfortunately you'll have to find another best trap.

76f3ead3aa977d876bcf3331d35a36e9

(4620)

on February 19, 2011
at 01:46 AM

Sorry to butt in here with a slightly off-topic question, but Kamal you mention leangains eating windows as having the ability to create AGEs (I think). What is the reasoning behind this? Not arguing, just curious!

100fd85230060e754fc13394eee6d6f1

(18706)

on February 19, 2011
at 01:43 AM

If, as a zero-carber, I'm falling into a trap, it's the best trap of my life, which dramatically changed for the better when I dropped the last bit of carbohydrates. I might also mention 45+ lbs of fat which VLC did not budge. No argument can change that.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 01:37 AM

I see your edit and appreciate your point better. However, I (naturally!) have a couple counterpoints. First, x-rays are miniscule in their radiation compared to something like a trip on a airplane. If you minimize CT scans and PET scans, that's a different story. Second, cumulative AGEs would be less telling than AGEs per day. If you look at any number accumulated over a lifetime without the context of how the body handles it per day, it will look scary. That being said, I don't eat smoked food so much, and slow-cook alot, for the same reasons you do.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 12:49 AM

Again, it's not a poison, using normal terminology. If it is, so is grilling/baking/leangains eating windows/etc etc. The ability to create an AGE is not equivalent to poison.

Medium avatar

(39821)

on February 19, 2011
at 12:44 AM

I assumed that the OP was referring to conditions under which fat loss is optimized. A healthy person at what they consider to be an ideal weight isn't similarly constrained and can obviously tolerate a greater amount of fructose without it interfering with their goals.

Medium avatar

(39821)

on February 19, 2011
at 12:41 AM

Fructose is a highly reactive reducing sugar that creates AGEs to a greater extent than glucose, lactose etc. The ability to tolerate a poison doesn't make the avoidance misguided.

Medium avatar

(39821)

on February 19, 2011
at 12:38 AM

AGEs are a poison that is created at any dose by fructose.

Ac1e55cf06c2180f4008ff01953d10dd

(3524)

on February 19, 2011
at 12:36 AM

I agree with Kamal. My personal experience, and I have read it somewhere too is that if you eat up to 50 grams of fructose per day you should have no problem at all.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 12:24 AM

I respectfully disagree. The dose makes the poison, and as in most cases, the liver is our poison hotline. Luckily, the liver is vast in its resources. Not so vast that you can drink soda and eat ho-hos everyday. But not so wimpy that eating some fruit will overwhelm your strongly evolved tendency towards homeostasis. I don't immediately see why you pegged fructose as being 3-4x more lipogenic then starch, but I'd love to see some evidence. And the minimum daily requirement doesn't apply here--there is no minimum daily requirement for saturated fat either, and we love it for other reasons.

0bcefaa82dc94f93ce705f86e235f335

(1591)

on February 19, 2011
at 12:12 AM

I am so glad you asked this question, because in the back of my mind I have been wondering about all the tomatoes and onions in my diet, specifically. :) They taste like candy to me now... especially the little grape tomatoes. Om nom nom!

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11 Answers

9
21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 12:33 AM

As I implied in my comment above, this appears to be overkill to me. Fructose is not poison, no matter what terms are thrown around. Eating too much fructose is obviously bad for many reasons (liver health, AGEs, absorption, etc). But the dose makes the poison, and fructose is not an alien substance that the body can not fathom. For example, we have set metabolic pathways for it...people have eaten it since humans have been alive...we are not morbidly obese people or gravely ill people who need to dissect grams of each nutrient.

This is falling into the same trap as zero-carbers and fruitarians fall into (sorry for that last comparison!) 4 grams of fructose a day is tiny, and worrying about fructose in onions is a slippery slope. Our bodies are quite robust, especially if they haven't been irrepairabily metabolically deranged. If you're looking for thresholds for fructose, my guess is it shouldn't be in the 4 gram range, but more like the "couple pieces of fruit" range, unless you have some illness or feel acutely bad eating it.

100fd85230060e754fc13394eee6d6f1

(18706)

on February 19, 2011
at 01:43 AM

If, as a zero-carber, I'm falling into a trap, it's the best trap of my life, which dramatically changed for the better when I dropped the last bit of carbohydrates. I might also mention 45+ lbs of fat which VLC did not budge. No argument can change that.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 01:55 AM

"Best trap of my life", nice! The trap here would be if zero carb wasn't noticably doing you good and you wanted carbs, but theoretical benefits down the road changed your habits. So unfortunately you'll have to find another best trap.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 03:56 AM

My bad! Weight change is still pretty hard to ascertain though. Even validated dietary questionares (Food frequency questionares, dietary recalls, food diaries) are contentious in their ability to predict weight change based on nutrient intake. So what I really mean is, be careful about your conclusions.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 02:31 AM

Have you considered that a weight experiment has low sensitivity to ascertaining dietary change influences? In other words, weight changes rely too much on water weight, hormones de jour, etc. The marginal effects of 0-10 grams of fructose a day would be tiny unless there was some crazy feed-forward lipogensis mechanism (fructose's aren't that crazy if I recall correctly). A much greater calorie burn would be using a standing desk. Standing burns at least 25 calories per hour more than sitting, which amounts to 200 calories per work day!!!

100fd85230060e754fc13394eee6d6f1

(18706)

on February 19, 2011
at 03:07 PM

Yeah, I see what you're saying. I definitely wouldn't keep it up just for theory's sake -- I enjoy vegetables too much. Regarding the calorie difference, I think it's possible that a change in hormonal response could have a more dramatic effect, even with only a small caloric change.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 06:14 AM

Actually, I think it's gonna be simple. When I eat starch but not fructose, either I lose weight (more than a few pounds either way) or I don't. Or I gain. Of course, whatever happens for me does not mean it will happen for another. But if it happens to me, it will probably happen to some others and will be worth keeping in mind as a possibility/option.

Medium avatar

(39821)

on February 19, 2011
at 12:44 AM

I assumed that the OP was referring to conditions under which fat loss is optimized. A healthy person at what they consider to be an ideal weight isn't similarly constrained and can obviously tolerate a greater amount of fructose without it interfering with their goals.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 10:42 AM

It might take a while though-- at 3500 kcal per pound of fat, with usual daily caloric changes of (-100 kcal) producing weight change, it would take 210 days to lose six pounds. Introducing any other changes during that seven month period would mitigate the results.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 03:44 AM

I know about water weight change, but that is only a few pounds. I look at trends and how my pants fit. I would not be so foolish as to consider only a few pounds on one day to be actual clear weight loss. And if you read my post, I do not work at a desk, nor do I sit during the day much so the advice about a standing desk does not apply.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 10:39 AM

True, whether the effects are due to the nutrient change or due to placebo effects or other correlates, it's still weight loss.

Ac1e55cf06c2180f4008ff01953d10dd

(3524)

on February 19, 2011
at 12:36 AM

I agree with Kamal. My personal experience, and I have read it somewhere too is that if you eat up to 50 grams of fructose per day you should have no problem at all.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 02:17 AM

One thing I plan to experiment with, how much of the prob is fructose and how much is just carbs in general? If it's only fructose, then one should still be able to eat a fair lot of white potato, still avoid much fructose and still not gain weight. But if other carbs are also a prob, then the potato experiment should fail.

8
Fbbbdf1d0a7d6d5067a106af062c7ce6

(745)

on February 19, 2011
at 01:34 AM

50g/day; not by coincidence (since both are metabolized by the liver), this is the same amount of alcohol that is associated with increased risk of nearly all types of cancer

0bcefaa82dc94f93ce705f86e235f335

(1591)

on February 19, 2011
at 03:35 AM

Do you have a cite, by any chance? Thanks! :)

Fbbbdf1d0a7d6d5067a106af062c7ce6

(745)

on February 19, 2011
at 04:57 AM

First heard the 50/50 comparison via Mat Lalonde at OPT CCP Nutrition level-1 certification. Looks like Mat wasn't BS'ing (he does, after all, have a PhD in organic chem) http://en.wikipedia.org/wiki/Alcohol_and_cancer#Alcohol_consumption_of_50g_or_more_per_day_increases_risk

7
Medium avatar

on February 18, 2011
at 11:39 PM

It is my belief that fructose is the most lipogenic naturally-occurring substance that we encounter. There's a whole host of problems ranging from adiposity to dyslipidemia to the creation of AGEs. These are obviously much worse with large amounts of unbound fructose, as occurs in products containing HFCS. Honey also technically has a large amount of free fructose, but there are other factors that supposedly mitigate that fact. If I were working for a pharmaceutical company and was tasked with creating obesity in a pill at low cost to the company, I would just make a pill that was pure fructose. That's one sugar pill that wouldn't be a placebo.

I'm of the opinion that we should count fructose as being more of a dense carbohydrate inasmuch as lipogenesis is concerned. I'm not sure how to fully quantify the effect, but I count grams of fructose as 3-4X that of starch. While it's true that insulin will store extra glucose (that which can't be stored in muscle or the liver as glycogen) as fat, there is just more going on with fructose.

I think this is an excellent piece about how we've evolved alongside fructose: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2917125/

I get only what fructose is in spinach and potato currently because I feel that the best "bang for your buck" when it comes to fat loss comes from first decreasing fructose as low as possible, then decreasing starch to where it is supplying only enough glucose to replete glycogen stores.

There is no minimum daily requirement for fructose, and really, any amount of it will be more toxic than the equivalent amount of glucose.

Edit: I suppose my primary goal in all of this is longevity, and as such, I'd like to stack the deck in my favor to the greatest extent. I have mechanisms whereby the DNA damage from ionizing radiation produced by diagnostic x-rays can be repaired. Does this mean that I should be cavalier about x-rays and radiation in general simply because my body is robust enough to handle the occasional x-ray? No, I'd rather avoid them unless I break a bone or something so I have that much more chance of not developing cancer. This is the same motivation that leads me to cook meat at low temperatures. It's not going to kill me today or tomorrow if I don't, but who knows what that effect is over decades.

20g of fructose a day doesn't sound like a lot, but that 15g difference over 80 years is 438,000 grams of fructose. That's a lot of AGEs. I rather think that makes a difference.

Those saying "you'll have to pry the fructose from my cold, dead hands" may be creating something of a self-fulfilling prophecy.

76f3ead3aa977d876bcf3331d35a36e9

(4620)

on February 19, 2011
at 01:46 AM

Sorry to butt in here with a slightly off-topic question, but Kamal you mention leangains eating windows as having the ability to create AGEs (I think). What is the reasoning behind this? Not arguing, just curious!

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 12:24 AM

I respectfully disagree. The dose makes the poison, and as in most cases, the liver is our poison hotline. Luckily, the liver is vast in its resources. Not so vast that you can drink soda and eat ho-hos everyday. But not so wimpy that eating some fruit will overwhelm your strongly evolved tendency towards homeostasis. I don't immediately see why you pegged fructose as being 3-4x more lipogenic then starch, but I'd love to see some evidence. And the minimum daily requirement doesn't apply here--there is no minimum daily requirement for saturated fat either, and we love it for other reasons.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 02:27 AM

Phoenix-- that was speculation on my part. The reasoning is something like this: Large dose of exogenous AGE in small time window --> overwhelming body's capacity to eliminate AGEs through excretion or protein renewal. Hmmm...maybe isn't as solid as it sounded before.

Medium avatar

(39821)

on February 19, 2011
at 12:41 AM

Fructose is a highly reactive reducing sugar that creates AGEs to a greater extent than glucose, lactose etc. The ability to tolerate a poison doesn't make the avoidance misguided.

Medium avatar

(39821)

on February 19, 2011
at 12:38 AM

AGEs are a poison that is created at any dose by fructose.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 12:49 AM

Again, it's not a poison, using normal terminology. If it is, so is grilling/baking/leangains eating windows/etc etc. The ability to create an AGE is not equivalent to poison.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 01:37 AM

I see your edit and appreciate your point better. However, I (naturally!) have a couple counterpoints. First, x-rays are miniscule in their radiation compared to something like a trip on a airplane. If you minimize CT scans and PET scans, that's a different story. Second, cumulative AGEs would be less telling than AGEs per day. If you look at any number accumulated over a lifetime without the context of how the body handles it per day, it will look scary. That being said, I don't eat smoked food so much, and slow-cook alot, for the same reasons you do.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 07, 2013
at 07:13 AM

i totally agree with you Travis, 20g of fructose a day kept me fat (30-40lbs overweight). mind you, i'm mongolian and a bit of an extreme metabolic case

3
06d21b99c58283ce575e36c4ecd4a458

(9948)

on February 19, 2011
at 02:17 AM

For many of the newer paleohacks here, Dr Lustig at UCSF School of Medicine, Pediatric Obesity specialist, has a good lecture which covers the evils of fructose that is a couple of years old. http://www.youtube.com/watch?v=dBnniua6-oM

There is a lot of chemistry that is way over my head...so I just accept the fact that table sugar is half fructose and half glucose. I avoid all the plain sugar and all the sugar words ending in "ose".

Consumption of fructose brings on the following over a lifetime:

An increase in visceral fat, the kind that embeds itself between tissues in organs

Less sensitivity to insulin, one of the first signs of diabetes

Increased fat production in the liver

Elevated LDL (bad) cholesterol

Increased levels of triglycerides http://www.sixwise.com/Newsletters/2009/April/29/Glucose-Fructose-Sucrose-Whats-the-Difference.htm

And fruit has some naturally occuring fructose so I also avoid. It is way too sweet for marketing purposes due to being hybridized and our ancestors never could eat fruit year around...except for the few folks in the tropic regions and Africa.

Visceral Fat and non alcoholic fatty liver disease are nothing I want to have anything to do with. I have been working on my VF for 3 years since going paleo and I am winning....almost. The project is not yet complete, though.

06d21b99c58283ce575e36c4ecd4a458

(9948)

on February 19, 2011
at 03:04 AM

Well, general opinion is that fruit our ancestors ate might be 1/20th as sweet as the fruit we have now....thus a tiny amount of fructose. And many of us migrated north to cold climes where fruit was only available a few months during the summer and fall. And the fructose intake was pretty small. Who knows, but when we inundate our bodies with these modern day super sweet fruit year round, I am pretty sure we do not have the capacity to metabolize that much sugar on a daily basis efficiently...plus add in the modern sweet tooth for raw sugar products...and we have a recipe for disaster.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 04:19 AM

Africans' current fruit intake doesn't reflect past intake. Current hunter gatherers have been crowded out geographically and economically. Africa in paleolithic times was more temperate, and fruit was the only way to satisfy your sweet tooth, plus it was not harvested by multinational companies. I bet they ate a ton of fruit! (compared to current Americans, that is)

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 06:23 AM

Kamal, berries are something that often take time to harvest. I remember once when someone interviewed an Australian aborigine on the subject of survival who explained that although he knew berries were growing some distance away, the energy required to walk so far would be greater than the sustenance gained from a few berries.I don't think we can say for sure what fruit the ancient paleos ate or did not eat. And it probably varied quite a bit depending on location. Even in the jungle you may have to walk a long way to get to an edible fruit tree and it doesn't fruit all year long either.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 04:26 AM

It would be hard for berries to be 1/20th as sweet as modern fruit. Take the blueberry for example. One serving of wild blueberries has 3.5 grams of fructose. I'm trying to imagine how bland and microscopic paleo berries would be that have 1/20th of that amount (i.e. 0.18 grams of fructose). Isn't fructose supposed to help in seed spreading for some fruits? That makes me suspicious of the 1/20th figure.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 03:48 AM

How much fruit do the Africans really eat? The tribes I have seen seem to be eating a lot of meat and tubers and only some fruit. Plus they are more active. More fruit might be fine for those with undamaged metabolisms and/or an active lifestyle, but seems to be more of a prob for those who do not fit that bill. What is good for the healthy is not always what is good for the sick.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 02:45 AM

However, we all came from the few folks in the tropics and Africa. Have we lost the ability to metabolize fructose in comparison to Africans?

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on February 19, 2011
at 11:58 AM

Dexter in the article you link says - "After drinking either a fructose- or glucose-sweetened beverage that made up 25 percent of their daily calories for 12 weeks..." No one thinks drinking 25% of you calories as refined fructose is good. If you could find a study showing that 5% of calories from fructose in whole foods causes any of those negative effects I would pay more attention.

21fd060d0796fdb8a4a990441e08eae7

(24543)

on February 19, 2011
at 08:44 AM

Isn't Australia pretty sparse with regards to vegetation, compared to other equatorial geographies? Anyways...when I had previously asked a question questioning paleo egg availability, everyone was like "dude, they would have totally known where all the eggs were and eaten them, and some birds lay all the time". Point being, fruit might be held to a bit of a double standard here. Hunting animals is very difficult with crude weapons and requires not just walking but treks. Finding fruit trees and berry bushes is relatively easy. It's even easier than digging up tubers.

Ac1e55cf06c2180f4008ff01953d10dd

(3524)

on February 19, 2011
at 03:26 AM

Dexter many wild fruits contains lots of fructose. And we all come from Africa, except for the last 20k years which, according to paleo are of little DNA relevance...

Ce2968ab71119c736ba9d83841c5718a

on September 13, 2012
at 02:18 PM

"However, we all came from the few folks in the tropics and Africa. Have we lost the ability to metabolize fructose in comparison to Africans? " <-- That's not so hard to imagine, the did lose the sun protecting skin pigments...

2
100fd85230060e754fc13394eee6d6f1

(18706)

on February 19, 2011
at 12:02 AM

My general philosophy about such experiments is to start with complete elimination. If you have some sort of intolerance to a substance itself or some common dietary item you eat that carries it, you might not feel a big difference unless it is totally gone. I can't remember where I read this idea recently, but toxins in the body may have a superlinear effect with dosage. The bonus with this method is that your body can get really clear of many substances, and when you reintroduce them you might see a sharp difference you wouldn't necessarily see with just a reduction.

I'm also influenced by my own experience of a vast difference in my own health between a very low carb diet and a zero carb one.

Anyway, however you decide, best of luck. Let us know how it goes.

P.S. What kind of magnesium do you take? A few months ago I changed from oxide to citrate, and it was amazing. I actually felt almost euphoric for a period of a few weeks, after which the same dose became too much and I settled down at a lower dose.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 02:06 AM

I have done close to zero carb extremely low fructose in the past so this is not really a new experiment except this time I am paleo instead of just lowcarb. I really don't have an obvious issue with fructose in moderation other than it seems to lead to a few extra pounds, although I am not sure if under 4 grams per day would still have much effect. As for magnesium, I use chelated magnesium glycinate/lysinate from Albion labs. There are actually several vitamin companies that use the albion labs stuff. I started on this one as research suggested it is very good stuff and I like it.

3fe2bf1367970868757ddf7ed7c62531

(817)

on January 10, 2013
at 08:26 PM

I started taking magnesium oil via the skin. About one teaspoon rubbed on my stomach before bed. Best sleep ever, most vivid dreams that I can remember all day! I also take some citrate sometimes too.. Starting to take magnesium has been one of the best things ever!

1
35cebc412367f53cbc1cb804d7a72375

on January 07, 2013
at 11:36 PM

The bad news in all of this is fructokinase. Read The Fat Switch by cardiologist/renal specialist, Richard J. Johnson, M.D. It explains that excessive amounts of fructose (and sucrose--table sugar--is 50% fructose) in our diets is the problem. There are relatively small amounts of fructose in fruits (a small Valencia orange has a little over 2 grams of fructose) but a 12-oz. can of orange soda has 26 grams of fructose in a total sugar load of 44 grams. THAT is the problem. No one pigs out on 10 oranges in one sitting (or even in a day) but it is easy to quaff a can of orange soda in one sitting (that is, if you like fake orange flavoring--yuk). Fructokinase is the enzyme that is used by the liver to assimilate fructose and most of the destructive metabolic problems come from the action of this enzyme in raising uric acid levels. Because humans lack the ability to lower their own uric acid levels---we don't have uricase--high uric acid creates a host of problems in the body. Any substance taken in excess can be potentially lethal (remember the deaths that occurred from drinking too much water?) A couple of servings of fruit have health benefits that make taking the fructose hit worth it. Fruit can have a powerful healing effect on the body, just as vegetables do. I personally eat a lot more vegetables than I do fruit---I listen to my body and it tells me to eat a lot of vegetables and not so many fruits.

35cebc412367f53cbc1cb804d7a72375

(10)

on January 08, 2013
at 12:04 AM

p.s. Researchers have also discovered that the bodies of some (maybe all) obese people can convert blood glucose into fructose! So keeping total carbs down (in order to keep blood sugar down) is important too.

1
A18481e4b0edc283d5a84a2321001c79

(50)

on February 18, 2011
at 11:38 PM

I think a good chunk of it depends on individual body types and tolerances. I have some friends who eat tons of fructose laden foods, who don't get cravings after eating them and are still easily able to lose weight. For myself, if I have too much fructose I end up going into a carb craving and its also much harder for me to lose weight. I am fairly active, I work out 5 times a week for 45 minutes (crossfit and kettlebells), but I find that I still need to be careful about my fructose intake.

0
77877f762c40637911396daa19b53094

(78467)

on April 07, 2013
at 07:20 AM

x<0 fructose is poison

0
Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 07, 2013
at 07:14 AM

if you're super sensitive to fructose, maybe its worth cutting them all out. I'm mongolian and our ancestral diet consists of nothing but meat (lamb, beef) and dairy (lactose, which is glucose + galactose) with the occasional wild vegetable (fibrous, little fructose) and seasonal tart berries (again only seasonally). i used to be morbidly obese and i lost the weight getting rid of all fructose sources meticulously. i still eat white rice and milk as carb sources, but little vegs and no sweet foods

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 08, 2013
at 08:06 AM

yes im lactose tolerant. mongolian nomad genes babyyy!!

D33a8d5f095a8532ddf7a0d6c27bfe63

(578)

on April 07, 2013
at 10:03 AM

That's interesting. So I assume you're lactose-tolerant, unlike most Asians? What do you normally eat with rice, then? Just meats? Any tubers at all?

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 08, 2013
at 08:07 AM

tbh i think mongolians are almost not like asians at all - physically or metabolically. we're more caucasoid, my build and musculature is more like that of a Kazak or Russian, and I have blue eyes btw.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on April 08, 2013
at 08:05 AM

yeah lots of meats (no fructose), some dairy, eggs, very little veggies and a good amount of white potato/white rice (almost fructose free). no diet sodas, just herbal tea/coffee with cream. its actually what i'd prefer to eat anyways. i like meat + clean starch

0
C66fcd14c6fb1962cc46882d8943bb3f

on January 10, 2013
at 03:19 PM

So, what CAN I eat if I can't have carbs and apparently I now have to stay away from fructose-containing fruits and veggies...

There's no way I can get enough calories for the day from protein and greens alone...

D33a8d5f095a8532ddf7a0d6c27bfe63

(578)

on April 07, 2013
at 11:13 AM

I don't think you need to stay away from fructose-containing veggies. It's dose-dependent so if you're doing, say, under 20g of fructose per day, I think that's sufficient. Plus there could be some hormetic effect of fructose intake. Like most things, I tend to think it's the J curve that determines optimal vs. suboptimal.

0
0adda19045a3641edac0008364b91110

(1146)

on February 19, 2011
at 02:21 AM

I use to consume tons of tomatoes and onions because I was under the dumb belief that they contained no fructose, they were like candy to me. I would down about 2 whole onions steamed and seasoned with sea salt, cayenne pepper and lemon. Now I know better.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on February 19, 2011
at 11:48 AM

Please don't avoid onions or tomatoes due to the really tiny amounts of fructose they contain.

0adda19045a3641edac0008364b91110

(1146)

on February 19, 2011
at 02:45 PM

@ Eva, I have never had weight problems, even when my diet consisted of 500 grams of carbs, quite the opposite in fact (can't gain), so I can't say much on that subject. @ mathew... I will in no way avoid onions and tomatoes, I just won't eat as much as I was eating.

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on February 19, 2011
at 03:49 AM

Any diffs in weight or how you felt after you cut down on the tomatoes and onions?

742ff8ba4ff55e84593ede14ac1c3cab

(3536)

on January 08, 2013
at 01:57 AM

I had to downvote this answer. I can't believe how stupid I sound.

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