20

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Who has scientific evidence that eating lots of fruit is unhealthy?

Answered on September 12, 2014
Created December 08, 2010 at 4:15 PM

Who has evidence that eating a lot of fruit is unhealthy? We have good reasons to be scared of fructose used in soda and other processed products. That's whay most paleo's eat fruit in moderation, I think. But is there any evidence that there are negative consequences for our health?

Please, this time I'm not interested in personal anecdotes (although they are important), nor in theories, but in hardcore evidence.

Thank you!

3c6b4eed18dc57f746755b698426e7c8

(5152)

on June 22, 2011
at 04:24 AM

Correct. If Joe Paleo was hungry he would eat anything. However, he would not have absorbed harmful amounts of fructose, since most Paleo fruits would not have been honey-dew sweet as the modern fare bred for higher fructose concentration. With today's fruits, you arguably can ingest undue amounts of fructose.

B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 07:37 PM

I think what Ms. Minger's post illustrates is that there are 1000's of different species of fruit available. Now the question you have to ask yourself is this: What do humans do when a resource is available? We exploit it. I would even go as far as to say it's easier for a hungry untrained eye to spot fruit dangling from a tree than it is to locate a tuber but that's just speculation. Fruit is an easy source of energy and water.

B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 06:56 PM

"whereas Joe Paleolithic ate a few sour apple per week" Really? I didn't realize we had the anthropological evidence to confirm that.

B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 06:52 PM

Hence the "That's not proof but an interesting read on the 1000's of species of fruits out there." That was just an aside.

3c6b4eed18dc57f746755b698426e7c8

(5152)

on June 21, 2011
at 06:37 PM

Denise's post does not show that the Paleolithic man ate fruits as sweet as those available today. She made a case that wild, exotic fruits can in fact be very sweet. The issue here is per capita and pound per pound consumption. Take an apple, which would have been a seasonal item. An apple during the Paleolithic would be sour, bitter and barely edible. An apple today is 3x the size and much sweeter and is consumed year around. Joe Sixpack is consuming lots of apples, whereas Joe Paleolithic ate a few sour apple per week. Who would have consumed more fructose?

9a5e2da94ad63ea3186dfa494e16a8d1

(15833)

on June 21, 2011
at 06:24 PM

I have seen this argument elsewhere, that fruits and vegetables are "toxic". However, the presence of potential toxins is not the same as being bad for you, as the body may defeat those toxins and/or the overall benefit from eating fruits and vegetables may (in my opinion does) outweigh any negative effects.

9a5e2da94ad63ea3186dfa494e16a8d1

(15833)

on June 21, 2011
at 06:23 PM

Agree with Pieter, failing to have an effect on breast cancer and being bad for you are two totally different things.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on June 21, 2011
at 04:30 PM

There is certainly plenty of dietary misinformation there.

13b40c07d0aab810f48eec3d04877010

(410)

on December 10, 2010
at 12:02 AM

I've wondered about this... if cancer cells are stimulated by insulin/glucose, why exactly do quick bursts cause more growth than steady release (if total amounts of insulin are the same)? My oncologist poo-pooed the anti-sugar argument saying that cancer cells will grab as much glucose as they need no matter what we eat. Of course I wasn't suggesting Paleo at the time, just no sugar... But, if the body has a specific range of glucose in the blood at all times, could she be correct?

F6c1df7d5699661bd1f0d6d0a6c17fc6

on December 09, 2010
at 11:43 PM

Interesting, but a) fruit need not be optimal and b) if they were slightly detrimental to the "host" it would be advantageous to be slightly addictive as well ;-)

A968087cc1dd66d480749c02e4619ef4

(20436)

on December 09, 2010
at 12:32 PM

Indeed, low fat may be the culprit. Its interesting that cancer prevention has long been touted as the reason to eat lots of fruit/veg - and yet it seems to have no effect. Personally, I feel that fruit/veg in the 50-100g/day carb range is good for gut health, if nothing else. Acid/base balance, maybe? Nutrients/antioxidants? I don't know. Veggies are filling and low calorie - so there's that.

A968087cc1dd66d480749c02e4619ef4

(20436)

on December 09, 2010
at 12:24 PM

Unless you are diabetic, your blood sugar should be mostly stable, in spite of eating fruit. Spiking insulin is not good vis-a-vis cancer, however, as it promotes growth, including cancer growth.

89e238284ccb95b439edcff9e123671e

(10299)

on December 09, 2010
at 06:44 AM

@w8liftingmom, my question is exactly about how fruit differs from glucose and fructose and the other parts it is made up off. Not about sugar of fructose...

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on December 09, 2010
at 06:24 AM

Cancer cells are very energy hungry. Sugar provides more intense quicker levels of energy which allows cancer cells to grow faster. But remember, cancer cells are human cells, so things that are good for them are not automatically bad for other healthy human cells. The problem in cancer treatment has long been that it's hard to hurt cancer cells without hurting regular cells. Because they are all human cells!

Cfccbcf3450ac4919311ded8ef162d49

(2312)

on December 09, 2010
at 06:06 AM

either way, doesn't sound like something I'd encourage.

4b97e3bb2ee4a9588783f5d56d687da1

(22913)

on December 09, 2010
at 03:32 AM

Glucose was only shown to feed, fructose was shown to allow and encourage division/multiplication... Cancer that can do advanced math is scary...

D738a5b2a67f3c36518a2ac9f32d27af

(821)

on December 09, 2010
at 02:58 AM

I'm curious if "low in fat" is the crucial factor here.

89e238284ccb95b439edcff9e123671e

(10299)

on December 08, 2010
at 08:39 PM

I guess what the great Peter Hyperlipid wants to show is that lots of fruit is not necessary for good health. That doesn't mean they are bad for health. And cancer surviving is not the same as keeping good health. But like Matthew said, too much to discuss for a comment box...

89e238284ccb95b439edcff9e123671e

(10299)

on December 08, 2010
at 08:38 PM

I guess what the great Peter Hyperlipid wants to show is that fruit is not necessary for good health. That doesn't mean they are bad for health. And cancer surviving is not the same as keeping good health. But like Matthew said, too much to discuss for a comment box...

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on December 08, 2010
at 08:24 PM

I have problems with the interpretations of those studies. Beyond a comment box to discuss though.

77732bf6bf2b8a360f523ef87c3b7523

(6157)

on December 08, 2010
at 05:40 PM

Great questions!

89e238284ccb95b439edcff9e123671e

(10299)

on December 08, 2010
at 04:52 PM

indeed not really the same, but interesting nevertheless. thanks

9d43f6873107e17ca4d1a5055aa7a2ad

on December 08, 2010
at 04:37 PM

I'd researched this many times and the lack of studies that use actual fruit is quite stunning. I suspect it's because it's so hard to standardize.

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13 Answers

6
B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 12:33 PM

There is no hardcore evidence.

Have you read Ms. Minger's recent post: http://rawfoodsos.com/2011/05/31/wild-and-ancient-fruit/

That's not proof but an interesting read on the 1000's of species of fruits out there.

I understand that fructose and sugar is a concern for many people but quite honestly I feel the fear is irrational in most contexts. After all we were eating fruit before we figured out how to eat meat. Eating whole foods is a big picture approach to nutrition yet we isolate sugar and fructose out of the many many compounds in fruit and pretend that sugar and fructose act in a vacuum.

There are two things I know I liked as a child meat (and all it's trimmings) and fruit. I still eat a lot of fruit and suck on limes just like the rest of my family in Okinawa. We tend to live longer than most so I'll continue to trust those instincts. My great grandma just died at 106 and my grandma is still alive and mobile as well. Grandma always encouraged us to eat good meat and fruit and I've never seen anybody completely destroy a chicken quite like her (it wasn't even worth throwing the bones to the dog after she finished with them). In the summer she'd always give us eggs every morning and fruit and for lunch/dinner some type of meat usually pork. She loves a good pork chop. She has several fruit trees in the backyard.

B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 07:37 PM

I think what Ms. Minger's post illustrates is that there are 1000's of different species of fruit available. Now the question you have to ask yourself is this: What do humans do when a resource is available? We exploit it. I would even go as far as to say it's easier for a hungry untrained eye to spot fruit dangling from a tree than it is to locate a tuber but that's just speculation. Fruit is an easy source of energy and water.

B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 06:52 PM

Hence the "That's not proof but an interesting read on the 1000's of species of fruits out there." That was just an aside.

3c6b4eed18dc57f746755b698426e7c8

(5152)

on June 21, 2011
at 06:37 PM

Denise's post does not show that the Paleolithic man ate fruits as sweet as those available today. She made a case that wild, exotic fruits can in fact be very sweet. The issue here is per capita and pound per pound consumption. Take an apple, which would have been a seasonal item. An apple during the Paleolithic would be sour, bitter and barely edible. An apple today is 3x the size and much sweeter and is consumed year around. Joe Sixpack is consuming lots of apples, whereas Joe Paleolithic ate a few sour apple per week. Who would have consumed more fructose?

B9cc28905ec54389c47cde031d709703

on June 21, 2011
at 06:56 PM

"whereas Joe Paleolithic ate a few sour apple per week" Really? I didn't realize we had the anthropological evidence to confirm that.

3c6b4eed18dc57f746755b698426e7c8

(5152)

on June 22, 2011
at 04:24 AM

Correct. If Joe Paleo was hungry he would eat anything. However, he would not have absorbed harmful amounts of fructose, since most Paleo fruits would not have been honey-dew sweet as the modern fare bred for higher fructose concentration. With today's fruits, you arguably can ingest undue amounts of fructose.

5
A968087cc1dd66d480749c02e4619ef4

(20436)

on December 08, 2010
at 06:17 PM

Peter at Hyperlipid has a number of posts on fruits and vegetables that are not very rosy. Nothing about just fruit, but very interesting:

http://high-fat-nutrition.blogspot.com/2008/01/there-are-people-like-these-scientific.html

http://high-fat-nutrition.blogspot.com/2007/12/fruit-and-vegetables-re-post.html

http://high-fat-nutrition.blogspot.com/2007/09/fruit-and-vegetables-last-post-almost.html

http://high-fat-nutrition.blogspot.com/2007/12/fruit-and-vegetables-in-holland.html

From the first link:

"CONCLUSION: Among survivors of early stage breast cancer, adoption of a diet that was very high in vegetables, fruit, and fiber and low in fat did not reduce additional breast cancer events or mortality during a 7.3-year follow-up period."

Pretty conclusive. No mincing of words.

You could say it didn't do any harm I guess.

Phew.

Peter

89e238284ccb95b439edcff9e123671e

(10299)

on December 08, 2010
at 08:38 PM

I guess what the great Peter Hyperlipid wants to show is that fruit is not necessary for good health. That doesn't mean they are bad for health. And cancer surviving is not the same as keeping good health. But like Matthew said, too much to discuss for a comment box...

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on December 08, 2010
at 08:24 PM

I have problems with the interpretations of those studies. Beyond a comment box to discuss though.

D738a5b2a67f3c36518a2ac9f32d27af

(821)

on December 09, 2010
at 02:58 AM

I'm curious if "low in fat" is the crucial factor here.

89e238284ccb95b439edcff9e123671e

(10299)

on December 08, 2010
at 08:39 PM

I guess what the great Peter Hyperlipid wants to show is that lots of fruit is not necessary for good health. That doesn't mean they are bad for health. And cancer surviving is not the same as keeping good health. But like Matthew said, too much to discuss for a comment box...

A968087cc1dd66d480749c02e4619ef4

(20436)

on December 09, 2010
at 12:32 PM

Indeed, low fat may be the culprit. Its interesting that cancer prevention has long been touted as the reason to eat lots of fruit/veg - and yet it seems to have no effect. Personally, I feel that fruit/veg in the 50-100g/day carb range is good for gut health, if nothing else. Acid/base balance, maybe? Nutrients/antioxidants? I don't know. Veggies are filling and low calorie - so there's that.

9a5e2da94ad63ea3186dfa494e16a8d1

(15833)

on June 21, 2011
at 06:23 PM

Agree with Pieter, failing to have an effect on breast cancer and being bad for you are two totally different things.

4
8287c6ddae0d78eae0a09fdd5999617c

(2581)

on December 09, 2010
at 09:51 PM

Despite its name, fructose is not only found in fruits, but also vegetables. Carrots, onions and sweet potatoes all have fructose.

I agree with Ned Kock that fructose in fruits may be good for you and only raises triglycerides in sedentary people eating large amounts of it (such as in soft drinks).

http://healthcorrelator.blogspot.com/2010/06/fructose-in-fruits-is-good-for-you.html

The HFCS debate is merely a lightning rod for criticism of processed food and added refined sugar. I think that is more what it is about than HFCS itself. The same people criticizing HFCS, are not going to be the type of people who extol "natural" cane sugar or corn syrup over HFCS. I definitely think the debate over HFCS has made it so people are wary of fructose in fruit and vegetables. I'm not worried.

Wild fruits are probably more nutrient dense (correct me if I'm wrong). Whereas an apple or a banana may not seem like much now in the way of nutrition. Soil depletion and over-domestication has probably decreased a lot of nutritional value. Fruit is definitely healthy, but it may be even healthier to choose less domesticated or wild fruits.

4
33ab3c085652a0cfbd7ab15c049afd1f

on December 08, 2010
at 08:21 PM

How about the arguments of those who are for fruit?

Ray Peat (the anti-PUFA, pro saturated fat scientist) is quite pro-fruit and somewhat anti-green leafy vegetables.

A particular plant will have a variety of defensive chemicals, with specific functions. Underground, the plant???s roots and tubers are susceptible to attack by fungi and nematodes. The leaves, stems, and seeds are susceptible to attack by insects, birds, and grazing animals. Since the plant???s seeds are of unique importance to the plant, and contain a high concentration of nutrients, they must have special protection. Sometimes this consists of a hard shell, and sometimes of chemicals that inhibit the animal???s digestive enzymes. Many plants have evolved fruits that provide concentrated food for animals, and that serve to distribute the seeds widely, as when a bird eats a berry, and excretes the undigested seed at a great distance. If the fruit were poisonous, it wouldn???t serve the plant???s purpose so well. In general, the plant???s most intense toxins are in its seeds, and the fruits, when mature, generally contain practically no toxins. Roots contain chemicals that inhibit microorganisms, but because they aren???t easily accessible by grazing animals and insects, they don???t contain the digestive inhibitors that are more concentrated in the above-ground organs of the plant.

Generally, fruits, roots, and tubers provide a high concentration of nutrients along with low concentrations of toxic antimetabolic substances.

http://raypeat.com/articles/articles/vegetables.shtml substances.

F6c1df7d5699661bd1f0d6d0a6c17fc6

on December 09, 2010
at 11:43 PM

Interesting, but a) fruit need not be optimal and b) if they were slightly detrimental to the "host" it would be advantageous to be slightly addictive as well ;-)

9a5e2da94ad63ea3186dfa494e16a8d1

(15833)

on June 21, 2011
at 06:24 PM

I have seen this argument elsewhere, that fruits and vegetables are "toxic". However, the presence of potential toxins is not the same as being bad for you, as the body may defeat those toxins and/or the overall benefit from eating fruits and vegetables may (in my opinion does) outweigh any negative effects.

3
B4aa2df25a6bf17d22556667ff896170

(851)

on December 08, 2010
at 04:42 PM

89e238284ccb95b439edcff9e123671e

(10299)

on December 08, 2010
at 04:52 PM

indeed not really the same, but interesting nevertheless. thanks

2
E5c7f14800c5992831f5c70fa746dc5c

(12857)

on June 21, 2011
at 05:54 PM

http://www.ncbi.nlm.nih.gov/pubmed/1884571

The effect of a high consumption of citrus fruit and a mixture of other fruits on dental caries in man.

The number of subjects included was: for the citrus-producing group 120 (55 men), for the mixed variety group 95 (49 men) and 50 (25 men) for the grain-producing group (control group)....

...The mean daily intake of added sugars (excluding that from the specific fruits to be investigated), was the highest for the control group...

...However, the highest DMFT (24.8) was found in the citrus-producing group, with less in the mixed variety fruit group (22.7) and the least in the control group (9.9). The sequence of the order of magnitude of the components (D, M, F) of the DMFT was the same as that for the caries experience as such. It is concluded that a high consumption of various fruits over a long period is associated with a high caries experience.

dmft=decayed missing filled teeth

Might not be unhealthy but it will probably rot your teeth out eventually.

2
62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on December 08, 2010
at 05:08 PM

Obvious problem for diabetics or prediabetics, whose glucose metabolism is already damaged. ALso potential problem for those who are not diabetic but with damaged metabolism and gain weight easily or are sugar addicts. Other than that, I see no reason, so far, to fear moderate whole fruit intake. However, I would agree it would be nice to see more research on it. Sadly, I think too many theories go straight from theory to fact without the intervening research. That's what has probably happened with fruit intake. Since 'everyone knows' it is good for you (and mainstream media includes fruit juice in that one), then they feel there is no reason to study it. As a former fruit juice addict that would go into the fridge about once an hour for a swig of sugar/fruit juice, I can say with confidence that fruit juice causes problems for some people, but I do seem to do OK with whole fruit instead.

1
7e36094a0f7a2fbad24290225405220b

(2064)

on June 21, 2011
at 04:18 PM

http://www.second-opinions.co.uk/why-eat-5-portions-1.html

A verty interesting article. The bit you need is on page 3.

0bc6cbb653cdc5e82400f6da920f11eb

(19245)

on June 21, 2011
at 04:30 PM

There is certainly plenty of dietary misinformation there.

1
3c6b4eed18dc57f746755b698426e7c8

on June 21, 2011
at 03:25 PM

Fruit itself probably does not wreck your metabolism. It is theoretically possible since it has fructose and fruit has higher sugar than vegetables and any other whole foods. But there is no evidence that fruit alone caused diabetes. Of course, things have changed a bit now, since all fruits are sweeter, bigger, and pack more fructose per gram than ever before.

Having said that, how many people only eat fruit and abstain from grains and other forms of sugar, what Dr. Lustig might call "exogeneous sugar." Very little, if any. We probably have the Kitavans and other Polynesians who were not exposed to gluten flour and exogenous sugar.

But consider a Joe Sixpack who wants to dig into his slice of apple pie: pie fillings filled with sugar, gluten crusts, and lots of exogeneous sugar. What you ate is toxic sugar explosion, not any fruit. There are very frew "fruitarians" in the West that are eating just fruit, veggies, and meats. The minute you mix fruit with gluten or exogenous sugar, you magnify the toxidity of fructose, whether deriving from whole foods, artificial sources, or from exogenous sugar. That's the argument.

1
Cfccbcf3450ac4919311ded8ef162d49

(2312)

on December 09, 2010
at 01:37 AM

don't cancer cells feed on sugar?

62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on December 09, 2010
at 06:24 AM

Cancer cells are very energy hungry. Sugar provides more intense quicker levels of energy which allows cancer cells to grow faster. But remember, cancer cells are human cells, so things that are good for them are not automatically bad for other healthy human cells. The problem in cancer treatment has long been that it's hard to hurt cancer cells without hurting regular cells. Because they are all human cells!

13b40c07d0aab810f48eec3d04877010

(410)

on December 10, 2010
at 12:02 AM

I've wondered about this... if cancer cells are stimulated by insulin/glucose, why exactly do quick bursts cause more growth than steady release (if total amounts of insulin are the same)? My oncologist poo-pooed the anti-sugar argument saying that cancer cells will grab as much glucose as they need no matter what we eat. Of course I wasn't suggesting Paleo at the time, just no sugar... But, if the body has a specific range of glucose in the blood at all times, could she be correct?

Cfccbcf3450ac4919311ded8ef162d49

(2312)

on December 09, 2010
at 06:06 AM

either way, doesn't sound like something I'd encourage.

A968087cc1dd66d480749c02e4619ef4

(20436)

on December 09, 2010
at 12:24 PM

Unless you are diabetic, your blood sugar should be mostly stable, in spite of eating fruit. Spiking insulin is not good vis-a-vis cancer, however, as it promotes growth, including cancer growth.

4b97e3bb2ee4a9588783f5d56d687da1

(22913)

on December 09, 2010
at 03:32 AM

Glucose was only shown to feed, fructose was shown to allow and encourage division/multiplication... Cancer that can do advanced math is scary...

89e238284ccb95b439edcff9e123671e

(10299)

on December 09, 2010
at 06:44 AM

@w8liftingmom, my question is exactly about how fruit differs from glucose and fructose and the other parts it is made up off. Not about sugar of fructose...

0
396679d1e1357eb7e9397ca34c8773ea

on June 21, 2011
at 05:33 PM

I cannot remember if fruit was used but this is an excellent piece by Gary Taubes on sugars and i believe fruit as well. http://www.nytimes.com/2011/04/17/magazine/mag-17Sugar-t.html

0
5e36f73c3f95eb4ea13a009f4936449f

(8280)

on December 09, 2010
at 08:29 PM

A mouse study for fructose and transfat (although not fruit's per se). http://www.consumeraffairs.com/news04/2010/06/fructose_trans_fat.html

0
87c70cb6d22de2a71fd39a7bb4a63a2b

(40)

on December 08, 2010
at 08:43 PM

Wiley makes some interesting arguments about seasonal fructose consumption as an evolutionary primer for winter pregnancy in Sleep, Sugar and Survival.

I'm a sucker for old stuff - old TV shows, old movies, and old research - so I always like checking out what they were talking about forever ago. This is one I kept from my early adventures. Postulates about fructose, but not fruit.

http://www.ajcn.org/content/20/2/131.full.pdf+html

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