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Why does fruits with similar Glycemic Load have different recommendations?

T

TSL

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7
Type of diabetes
Prefer not to say
Treatment type
Diet only
Hi! I have read in many places that glycemic load is a much better indicator (than glycemic index) of what is good/not suitable for diabetics. Now, as an example, I want to mention two fruits....blueberry and pineapple. Both of these fruits have a similar glycemic load but why is blueberry considered good and pineapple bad?
 
Hi TSL and welcome to the forums. Personally I pay no attention to Glycaemic whatever as it seems to make zero difference to me. Others have different experiences.

The blueberry/pineapple thing is I guess because pineapple has more sugar in various forms:

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Low-Carb Fruits and Berries – the Best and the Worst - Diet Doctor

What are the best and the worst fruits and berries to eat on a low-carb diet? Here’s the short version: most berries are OK low-carb foods in moderate amounts, but fruits are candy from nature (and full of sugar). For more details, check out this amazing visual guide, with the lower-carb options...
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I haven’t heard of Glycemic load before but I don’t follow the GI principles. I test my blood glucose before and 2 hours after eating so I know what I can eat and what’s bad for me (everyone reacts differently). I can eat a few blueberries and not get too much of a rise in BG but if I eat pineapple it goes through the roof!
 
Where are you seeing that the glycemic loads are similar?
Different resources list differing answers depending on portion size and even variety of fruit.
 
Are you talking fresh whole pineapple, or canned in syrup which is pure sugar? for Pineapple, the pulp has a lower sugar content than the core. also the pineapple in tins is generally riper than fresh fruit from the market, and so has a higher sucrose content (fruits as they ripen convert the fructose and glucose to sucrose, hence their sweetness grows as they ripen). It is well known that tropical fruits are more diebetic unfriendly compared to temperate fruits.
 
KennyA said:
Hi TSL and welcome to the forums. Personally I pay no attention to Glycaemic whatever as it seems to make zero difference to me. Others have different experiences.
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Thank you! The website you shared shows that both blueberries and pineapples have 12 net carbs per 100 grams. See what I mean? Yet, blueberries are good and pineapples are bad. I wonder why.
 
MissMuffett said:
I haven’t heard of Glycemic load before but I don’t follow the GI principles. I test my blood glucose before and 2 hours after eating so I know what I can eat and what’s bad for me (everyone reacts differently). I can eat a few blueberries and not get too much of a rise in BG but if I eat pineapple it goes through the roof!
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In simple terms, Glycemic load is a number assigned to one serving size of different food indicating how drastically it makes your blood sugar rise. At least that's what the experts say. The point you make about eating pineapple making your BG go up through the roof is probably common to most people (although I never tested the difference on myself). I am just curious to know why do they then have similar Glycemic Loads.
 
TSL said:
Thank you! The website you shared shows that both blueberries and pineapples have 12 net carbs per 100 grams. See what I mean? Yet, blueberries are good and pineapples are bad. I wonder why.
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It could be that most people's BG simply isn't usually as affected by blueberries as they are by pineapple?? Disclaimer - I've not tested this on myself at all. I have however found that not all carbs have the same effect - eg I can tolerate legumes pretty well, but what on paper is a much smaller amount of carb in pastry will have a huge BG impact.

It is also possible that it's unwarranted carry-over of the "all berries good" idea - which is, to be fair, generally accurate. Raspberries/ blackberries/ strawberries are all in the 3-6% range.
 
TSL said:
Thank you! The website you shared shows that both blueberries and pineapples have 12 net carbs per 100 grams. See what I mean? Yet, blueberries are good and pineapples are bad. I wonder why.
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Blueberries (and blackberries and purple grapes) are high in anthocyanins (i.e. the blue colouring) which interferes with metabolism by inhibiting some enzymes in the gut.
 
HSSS said:
Where are you seeing that the glycemic loads are similar?
Different resources list differing answers depending on portion size and even variety of fruit.
Click to expand...
Portion size is actually taken into account by glycemic load. It is always the standard one serving size. Glycemic Index however only considers amount of sugar in 50 grams carbs. For example watermelon has a high glycemic index but low glycemic load because to get 50 grams of carbs, you'd have to eat a lot of watermelon! One serving size is considered ok.

But you are correct that variety of the fruit matters. I have been doing a bit of reading and glycemic load of fruits vary depending on where it was grown. But everywhere, some fruits are considered good, others bad.....I just took blueberries and pineapple as examples with similar glycemic load. As a newbie, I am sorry I am not allowed to share links. A site 'Mad About Berries' actually has better numbers for pineapple. A journal 'International tables of glycemic index and glycemic load values 2021' has blueberries GL as 8 while different pineapples vary from 6 to 12.
 
Oldvatr said:
Are you talking fresh whole pineapple, or canned in syrup which is pure sugar? for Pineapple, the pulp has a lower sugar content than the core. also the pineapple in tins is generally riper than fresh fruit from the market, and so has a higher sucrose content (fruits as they ripen convert the fructose and glucose to sucrose, hence their sweetness grows as they ripen). It is well known that tropical fruits are more diebetic unfriendly compared to temperate fruits.
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I am referring to fresh pineapple. Which is still considered not friendly for diabetics.
 
Oldvatr said:
Blueberries (and blackberries and purple grapes) are high in anthocyanins (i.e. the blue colouring) which interferes with metabolism by inhibiting some enzymes in the gut.
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Ok, I get that. But they say Glycemic Load considers everything. So you can estimate the impact of glucose just by looking at the number. Still not sure why they have similar glycemic loads.
 
Sadly I suspect this may be an academic exercise as the world moves to reduce air miles substantially to save thw planet, and fruits that are currently transported by air will become scarce and expensive in our shops, and instead Big ag will step in and synthesise the essence of fruit in a pill or a sachet, and we enter the ultra processed era.
 
TSL said:
Ok, I get that. But they say Glycemic Load considers everything. So you can estimate the impact of glucose just by looking at the number. Still not sure why they have similar glycemic loads.
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Looking at how GI is calculated it is based on 50g of total carbs. But something like fruit contains sugars in the basic form of glucose and fructose as well as the combined molecules of sucrose. We metabolise these different substances in different ways. The glucose goes to the blood, the sucose gets split into glucose (blood) and fructose and other saccharide compoiunds.

Now the fructose is not processed like the sugars, and goes straight to the liver without creating glucose. It used to be considered as inert and not contributing to our blood glucose levels. It does not at that stage enter the blood, but may do later when there is a demand for gluconeogenesis (creation of glucose from whats around at the time) so it remains stored in the liver, and is reckoned to be a significant factor in Non Alcoholic Fatty Liver Disease (NAFLD) So it is certainly not inert. but it does not contribute to the meter reading.


So GI being all carbs is not accounting for the ratio of fructose to other saccharides in the fruit, which varies with species and age and ripeness. For example, green bananas are less of a problem compared to the yellow or black bananas simply because they are largely fructose at that stage. similarly baby pototoes have less starch that converts to glucose than older potatoes simply because starch becomes more carby as the potato matures. Not all starches are resistant or inert and they change as the plant matures..

This is why the GI and GL indices are not very useful for blood glucose control.
 
TSL said:
Portion size is actually taken into account by glycemic load. It is always the standard one serving size.
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Yes it is but my point is is very arbitrary what a “standard” serving size is. With something like an apple easy enough. One. But when it’s a number of pieces or a part of a whole not so clear and can vary a lot more.
 
TSL said:
Thank you! The website you shared shows that both blueberries and pineapples have 12 net carbs per 100 grams. See what I mean? Yet, blueberries are good and pineapples are bad. I wonder why.
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I personally give the gi a miss. I cannot eat most fresh fruits as the will spike me regardless of what the gi says. An apple is a rarity now - I can eat a little peel but that's it.
 
I couldn't care less about GI, all that matters to me is what effect something has on ME. GI or GL tells me nothing, when i see how i react.
 
As I have to inject insulin whatever fruit I eat, I do not shy away from pineapple and find it does not spike particularly badly.
I wonder whether the “pineapples are bad” mantra has come fruit the “exotic fruit are high sugar“ generalisation whereas pineapple are very high fibre which will reduce the net carbs.
If I do not time my insulin dose accordingly, mangos and bananas will be less forgiving than pineapples.

I also try to stay away from the concept of “bad food”. There may be food that I am less tolerant to but considering it bad will lead to guilt which is terrible for mental health. It may only seem like a word but this is something which can certainly affect me. And it is important to manage all of your body not just the diabetes part.
 
Oldvatr said:
Now the fructose is not processed like the sugars, and goes straight to the liver without creating glucose. It used to be considered as inert and not contributing to our blood glucose levels. It does not at that stage enter the blood, but may do later when there is a demand for gluconeogenesis (creation of glucose from whats around at the time) so it remains stored in the liver, and is reckoned to be a significant factor in Non Alcoholic Fatty Liver Disease (NAFLD) So it is certainly not inert. but it does not contribute to the meter reading.
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This puzzles me. Apples are my go-to when my sugar drops too low and within minutes my blood sugar meter reading starts to go up.
 
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