What level of fructose/sugar/fruit consumption is safe?

[Esmée La Fleur]

in my studies of the hunting and gathering diets, i do not recall any group i studied as eating a lot of fruit. it is possbile that some hunters and gathers did eat some, but it was never the main part of their diet. the Yanamamo indians in the amazon eat lots of plantains, but they are not hunter-gatherers--they are slash-and-burn agriculturalists. please let me know if you come across a group of hunter-gatherers that relied largely on fruit. Every group of hunter-gatherers I read about ate wild game, tubers, legumes, and nuts, with occassional seasonal fruit, like the watermelon eaten by the Kung! in the Kalahari desert of Africa.

We were pushed out of the jungle before we became modern human beings and that was quite a long time ago, so I don't think we have had access to fruit year-round or any other sugar until very recently in our history. Some people can handle the change better than others, but since over 1/3 of all Americans are now classed as obese, I would say that quite a few of us are not genetically adapted for a diet high in fructose, whether from fruit or otherwise. My mother went on a LFRV with me for a year, and her HDL dropped to 14, her LDL went up to 145 (total cholesterol 189), triglycerides 179, and liver enzymes were in very bad shape with GGT at 210, ASAT at 91, and ALAT at 106! None of this good.

There is no modern society that eats a diet based on fruit and this is probably because it is not a sustainable diet for the majority of any human population. This does not mean some people cannot do so (as witnessed by Anne Osborne, Julie Suiter, and Kveta Martinec) and still be healthy, but it is very unlikely that the majority of people could.

I hope this helps to help clarify what I am trying to say. I really don't care what you, or anyone else, eat(s) as an individual, as long as you feel good doing it. That is all that really matters. I posted the above information for those who may not feel best on fruit and wonder why.

[MarkC]

Thank you Esmee, you have taught me something new. I never knew about the uric acid from breakdown of frucose and that we differ in our fructokinase levels. I had intuitively figured out that lots of fruit in the diet wasn't working for me but now I understand a little more why that is. I will check out that book by Richard Johnson. I think a small about of high-quality fruit is useful in the diet as a source of micronutrients but the evidence does seem to point to fruit not being a huge proportion of the paleo diet. Paleo people would have made dietary choices based on factors such as availability and satiety. Fruits are available for a limited time and when ripe are difficult to collect and transport. They also have a short period of ripeness, lack the fat which causes satiety, contain sugars which create hunger pangs, and are protein deficient. That is probably why they do not seem to be a major part of the diets of modern hunter-gathers.

[CitrusHigh]

Great info Esmee! I like your name. Being someone with problematic reactions to sugar I'm totally on board but I'm not advanced enough to know how the different sugars play a role in health. I've come at it more from a practical, in the strict sense of the word, than scientific approach. I knew something I was eating was causing my infections and other issues but took me a long time to narrow it down to sugar. I still don't do well with the stuff but can tolerate a lot more now that I'm RVAF. Thanks for sharing, will be reading in to it more!

[Esmée La Fleur]

You are welcome. Glad it was helpful to you both. I just received my copy of Fructose Exposed by Dr. Lyons and it already looks like a keeper. He says no more than 15 gms of fructose a day, while Dr. Johnson says no more than 30 gms a day.

I think that berries are one of the best choices in the fruit department fro atting phytonutrients without getting too much fructose.

[Aaaaaa]

Yeah, I have been thinking of switching most of my fruit over to berries...unfortuently the best ones this time of year are all frozen.  But I think they are individually quick frozen or something like that (Stahlbush Island Farms brand--they are SO much tastier than most frozen berries.  I should Brix-test them and see if they really are as good as they taste), so I imagine that will preserve a good amount of the nutrients.  I think vitamin C (and probably some enzymes and bacteria) are the main things that are depleted by freezing.
Berries do just seem to have the best sugar/fructose to nutrition ratio! :-)

[Esmée La Fleur]

yes, Stahlbush are the best in my opinion and I actually think they are better than most fresh i have tried because they can be pick RIPE without having to be shipped to market. I lived off nothing but goat milk yogurt and frozen raspberries for 2 whole years. it saved my life. i think frozen berries still have  alot of integrity.

[Aaaaaa]

Well thank you for that anecdote, Esmee!  That does make me feel better about frozen berries.  I think that fresh meat is a lot more important than fresh berries/fruits.  Obviously no frozen veggies, since they are mostly blanched (cooked), but those aren't TOO hard to find around here in the winter--unfortuently nothing locally grown though.

[goodsamaritan]

I don't know if this has been mentioned but Aajonus' opinion is 1 serving of fruit a day is the limit he recommends.

Maybe coconut milk he does not count as fruit.

[Aaaaaa]

Yeah, I don't think he counts coconut as a fruit--I think its technically a nut, right?  I would eat coconut, but I can't find a source of any good ones around here, as I live VERY far from anywhere that they can grow! :-(

What are your feelings regarding frozen berries/fruit, GS?  I'm sure you never have to resort to such things yourself (lucky!!!) but I was wondering what you thought about it. 

[goodsamaritan]

We don't get much berries like you do in your part of the world.  I don't usually like buying imported stuff.  We have some strawberries from the commercial mountain area, but they are sprayed, not organic. 

This morning I was walking around our village and came upon an aratilis tree with some ripe aratilis berries, I got 4 i think. 

There aren't enough berries in my part of the world to treat as staple food.

[Esmée La Fleur]

A dose of fructose induces oxidative stress during endurance and strength exercise.

Fernández JM, Da Silva-Grigoletto ME, Gómez-Puerto JR, Viana-Montaner BH, Tasset-Cuevas I, Túnez I, López-Miranda J, Pérez-Jiménez F.

Source
Lipids and Atherosclerosis Research Unit, Reina Sofia University Hospital, Córdoba, CIBER Fisiopatologia de la Obesidad y Nutrición (CIBEROBN), Spain. juf_nutryinves@yahoo.com

Abstract
This study sought to compare the time course changes in oxidative state and glycemic behavior when glucose or glucose plus fructose are consumed before endurance and strength exercise. After two weeks on a controlled diet, 20 physically trained males ingested an oral dose of glucose or glucose plus fructose, 15 min before starting a moderate-intensity 30-min session of endurance or strength exercise. The combination resulted in four randomized interventions: glucose or glucose plus fructose + endurance exercise and glucose or glucose plus fructose + strength exercise, which were implemented consecutively in random order at 1-week intervals. Plasma concentration of lipoperoxides, oxidized LDL, reduced glutathione, catalase and glycemia were determined at baseline, during exercise and acute recovery. Following the ingestion of glucose plus fructose, lipoperoxides, catalase and reduced glutathione depletion were significantly higher than following consumption of glucose, for both endurance and strength exercise (P < 0.05). Oxidized LDL-c was higher after glucose plus fructose than after glucose alone in endurance exercise (P < 0.05). There was no difference in the glycemic peak between glucose plus fructose and glucose ingestion in endurance exercise trials. In strength exercise, the post-absorptive glycemic peak was less when the participants ingested glucose plus fructose than glucose (P < 0.05), and a second peak was found in the recovery phase of this group (P < 0.05). In conclusion, the addition of fructose to a pre-exercise glucose supplement triggers oxidative stress.

[z87]

Maybe ambient temperature affects fructose metabolism?

I tolerate fruit much better in the summer and tolerate meat much better in the winter.

[balancing-act]

I tolerate fruit much better in the summer and tolerate meat much better in the winter.
[/quote]

Ditto. I find a significant difference. But I live up north.

[aLptHW4k4y]

Probably because we're usually more active (more carb use) in the summer?

[aLptHW4k4y]

A dose of fructose induces oxidative stress during endurance and strength exercise.

Interesting.. as far as I know for endurance training glucose and fructose are recommended in 1:1 ratio for fastest glycogen repletion, since they are metabolized via different metabolic pathways. Here's a recent paper which shows that fructose+glucose is likely superior for performance:

http://journals.lww.com/nsca-jscr/Abstract/2010/12000/Fructose_Addition_to_a_Glucose_Supplement_Modifies.19.aspx

I would take these studies with a grain of salt though, usually they are performed using pure glucose/fructose which may not translate perfectly to real life.

[Esmée La Fleur]

Dr. Robert Lustig in his lecture (viewable on YouTube) called Sugar: The Bitter Truth says that the only people who really benefit from fructose are ehdurance and high-intensity athletes because it does improve (re)hydration of the cells. So, you are correct about that. But that level of exercise may not be particularly natural, at least not on a daily basis, and it, too, has been shown to cause increased oxidative damage. Doug Graham has been eating a high-fructose diet and running long distances for years and, in my opinion, looks older than many others who do not eat a high-fructose diet or run marathons. Not that longevity is the be all and end all of life though; it is far more important to have fun and do what you love even if that entails a bit more oxidative stress than the average person.

[PaleoPhil]

People in the blogosphere didn't learn the lesson from the demonization of all meats based on questionable assumptions and shoddy studies on saturated fats and are now ramping up the demonization of all fruits based on multi-heated and refined high fructose corn syrup. There are some voices of reason in the Wilderness:

"It's pretty clear that unless you cross the line of 50 grams of fructose daily (Staffan Lindeberg  kept quoting the figure of 5 pineapples, which seems like nearly a physically impossible amount of sweet fruit for a non-fruitarian), your liver is well able to handle the amount in most fruit.  Going nutty with the dried fruit and fruit juice is a different story.  I think folks who have sugar-related emotional eating might to better getting rid of fruit for a time, or maybe forever, but for most it is a healthy part of the diet." -Emily Deans, PhD, http://evolutionarypsychiatry.blogspot.com/2012/03/reviews-of-escape-diet-trap-eat-like.html

[Esmée La Fleur]

According to Cron-O-Meter, 1 pineapple has 20 gms of free fructose and 25 gms of fructose bound to glucose (to form a sucrose molecule), so it looks like 1 pineapple would give a person close to the 50 gms you are referencing. However, several very reputable researchers in this field are recommending no more than 15-30 gms a day. The main thing is to watch your own body, as fructose will cause uric acid levels to rise. However, one person may only be able to eat 10 gms while another may be able to eat 50 gms with no problem, depending on each persons ability to process fructose. I personally know someone who gets gout with the inclusion of a very small amount of fruit in their diet. So, it is not just the HFCS that is the problem.

[Hannibal]

Although not all wild fruits are as big and sweet as our modern cultivars, at least some are, and certain varieties even surpass our deliberately-bred fruits in size and flavor. Nature—especially with selection pressure from other fruit-eating creatures—is perfectly capable of producing sweet (and sometimes massive) fruits without human intervention. It seems unlikely that early humans only ever encountered berries or other “small, bitter” fruits, and avoiding sweeter fruits on the basis of evolutionary history may be misguided.

Based on the limited research we have, wild fruits aren’t considerably different from cultivated fruit in terms of carbohydrate content, fructose content, or fiber content. Both wild and cultivated fruit seem to average around 90% of calories from carbohydrates, and have a sugar composition that yields roughly equal parts glucose and fructose. And both wild and cultivated fruit can be relatively high or low in fiber.

Although berries are often lauded as being lower in fructose compared to other fruits, from a calorie/energy standpoint, this just ain’t true!

Early humans may very well have had access to fruit for most or even all of the year. The fruiting seasons we witness in cooler climates—with most fruit appearing in the summer—doesn’t necessarily apply to our evolutionary homeland closer to the equator.

http://rawfoodsos.com/2011/05/31/wild-and-ancient-fruit/

So there had been lots of big sweety wild fruits in ancient and paleo times. On average - 50% fructose and 50% glucose. Those fruits had been the main source of carbohydrates for humans.
It's also not true that they were only a few months a year - the vegetation was all year round

[PaleoPhil]

Interestingly, Staffan Lindeberg reported in Food and Western Disease: Health and nutrition from an evolutionary perspective that his research found that wild fruits actually contain more fructose on average than domesticated fruits, not less.

He also said this on p. 115: "When fruits replace cereal grains, as will be the case for most Westerners with diabetes,  The amount of fructose in 500 g of fruit is approximately 25 g (88), while available evidence suggests that a fructose intake below 60 g is safe. (1568, 1857)"

However, I didn't check his cited sources.

There's also this research review that found that crystalline or pure fructose (excluding high-fructose corn syrup, which apparently was correlated with harm--I don't know why it would be worse than crystalline fructose) in low amounts was correlated with benefit, rather than harm:

Fructose consumption and consequences for glycation, plasma triacylglycerol, and body weight: meta-analyses and meta-regression models of intervention studies.
http://www.ncbi.nlm.nih.gov/pubmed/18996880

However, I didn't read the full study report, which is not available at the link, so maybe someone with access to it can poke holes in it.

[svrn]

iv been eating a lot less meat and a lot more whole fruit and juiced veges since its gotten really hot out here. Iv been feeling uncomfortable when iv tried to go against it due to my beliefs about diet but now that im just following my instinct I feel a lot better. I think its mainly the factors of personal need combined with season.