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.

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.

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.

all fruits are basically 50/50 fructose/glucose. the only source of glucose is from starches: potatoes, other tubers, and grains mostly (which all require cooking), so there really isn't any raw source that I am aware of. sugar of any kind is really not part of a raw paleo diet.

I think I have some useful information to add to this discussion.

I have been very sick for a very long time due to many weird food intolerances. My full history is much to long to go into at this time. However, I almost died about 7 years ago. By accident I discovered I could eat goat milk yogurt and raspberries. I ate only these two foods 5 times a day for 2 entire years. Then my body got tired of this and didn't want it anymore. I experienced enough improvement in my digestive capacity that I was able to switch over to raw beef, olive oil, and leafy greens. I ate this 3 times a day for the next 2 years.

However, I did not like eating animals, and I found Doug Graham's book on 80/10/10 RV and decided to give it a try. I knew from past experience that most all fruit did not make me feel particularly well (the raspberries were an exception), but I thought maybe it was because I always ate a pretty high fat diet, and maybe this was interfering with my body's ability to process the sugar in fruit (as Graham claims). I proceeded to eat the 80/10/10 way for the next 1.5 years, before coming to the conclusion that it was making me really sick and that low fat did not change my body's response to the sugar in fruit.

I became friends with a few other struggling 80/10/10-ers as we tried to figure out why the heck we felt so darn awful on that diet. Recently, one of these people found a book called The Sugar Fix by Dr. Richard Johnson (available through Amazon). This book is full of science and very eye-opening. I highly recommend it. The author explains that fructose metabolism created uric acid as a breakdown by-product. How much uric is created depends on how many fructokinase enzymes a pperson produces. The more fructokinase enzymes produced, the more uric acid that is created. Uric acid is directly linked to all of the Syndrome X illnesses (high blood pressure, high HDL cholesterol, low HDL cholesterol, high triglycerides, insulin resistence, and obesity).

There seems to be a subset of the population (30%?) that is much more fructose sensitive than others and it is most like due to the fact that they produce higher amounts of fructokinase enzymes than others. Glucose does NOT cause these problems. However, if you are fructose sensitive and develop insulin resistance, then your body will have difficulty removing all sugars from your blood stream and you will want to avoid glucose as well, until you things back in normal working order.

Okay, so honey is extremely high in fructose with very little glucose, therefore not recommended as a regular thing. Most fruit is 50/50 fructose/glucose; however, some fruits have much more fructose than glucose and this is not a good thing for people who are sensitive to fructose.

I could never figure out why certain fruit, like watermelon and pears, always made me feel super duper extra bad, and now I know: they have much higher levels of fructose than glucose. I have also recently discovered two disorders that prevent proper fructose metabolism.

The first is: Fructose Malabsorption http://en.wikipedia.org/wiki/Fructose_malabsorption

The second is: Hereditary Fructose Intolerance  http://en.wikipedia.org/wiki/Hereditary_fructose_intolerance

FM is believed to affect as much as 30% of the population to one degree or another; HFI, however is much more rare and is believed to occur in 1 of 20,000 people. After reading everything I can about all of these different "fructose" problems, I have come to the conclusion that my symptoms have a very close fit to HFI.

I share many similarities with others (whom I have met through another on-line forum dedicated to people with HFI) who have this illness, which are too numerous to explain here. I have not yet been tested (saving my money), but I have taken the step to remove as much fructose from my diet as I possibly can (it is not as easy as one might think especially if one wants to be a vegan!, since almost all vegies have some small amount of frucose as well as fruits), and I feel much better all ready.

In retrospect, I now realize that my two successful periods with yogurt/raspberries and meat/oil/green were most likely due to the extremely low fructose content of those foods. My point in offering you all of this information is to show that, yes, different people do react very differently to fruit and other sources of fructose in the diet than others, and we need to respect our individual differences.  If anyone has any questions about this please feel free to ask here or email me privately.

Esmée