Reliable GI data, and is it worth effort?

[IrvineHimself]

Reliable GI data, and is it worth effort?

When I next have some surplus cash, I intend to buy a cheap set of kitchen scales. In anticipation of this, I have been putting together a database of nutritional info supplied by the Sainsbury's website. (This is not a recommendation with regard to price/quality, it is just a convenient source of consistent, reliable data)

Along with comparison products, it is focused on the things/brands I am likely to buy. Already, even without the scales, it is not only giving me a deep insight into what should and should not be in my diet, but highlighting things that are not immediately obvious. For example: The effects of cooking on calorie content, or the fact that the data for the normalised 100g sample is potentially misleading.

Example: How the normalised carbs/100g data can be misleading

Product​	Carbs per 100g​	Carbs per slice​
Byg Rice Cakes​	81.5​	6.1​
Ryvita Original​	77.5​	3.9​
Ryvita Dark Rye​	66.6​	6.7​
Oatcakes​	55.4​	5.6​
White Bread​	45.6​	18.2​
Brown Bread​	36.7​	14.7​

Anyway, I was thinking about adding GI data, but can't find a reliable, easily referenced source and was wondering if:

1. If you can recommend a source for the Gi of common supermarket products; vegetables,; meat and meat substitutes; dairy products; cereals and breads... etc?
2. Noting that the number of grams of carbohydrate in a food can have a bigger impact on blood sugar levels than the glycemic index does and actual increases in blood glucose show considerable variability from person to person. is it worth the effort of including the GI data?

I would be grateful to hear your thoughts
Irvine

 

[helli]

I used to use this database (https://glycemicindex.com/) as I found it the most comprehensive.
Is it reliable? I think GI is one of those things which can be very personal so whichever source you use it is a general number, not the number for you.
This then goes back to the advice to test (before you eat and 2 hours later). Frustratingly, blood glucose testing meters and strips are rarely provided for type 2. But many people on the forum finds it is a great aid ti work out how their body reacts and adapt their diet accordingly.

 

[Docb]

For me, the GI concept is one of those things that seems good at first sight but its limitations begin to show up when you start to look a bit more closely. It is not unreasonable to suggest that different carbohydrates will turn up as blood glucose at different rates but the notion that you can describe this numerically such that the numbers can be universally applied goes too far.

The biggest problem for me is that the conversion rate will be a function of the way the gut performs and this will vary widely between individuals.

You also need to keep your wits about you when looking a carb content of foods. The things you quote in your list are all manufactured goods and a carb content can be sensibly quoted although you need to be aware that the regulations do not require the manufacturers to measure carb content, a reasonable estimate is acceptable. When it comes to fresh foods things get more difficult. You will, for example, find a carb value quoted for apples in standard tables. What you will not find is the variation between varieties, degree of ripeness and time in storage, all of which will affect the carb content.

My thought is that it is best to use concepts like GI for general guidance only. It will never be a substitute for eating something and measuring the effect on your system.

 

[Inka]

I think the GI fell out of fashion a bit in favour of the GL - glycaemic load. That is, we rarely eat foods in isolation so you can, in theory, ameliorate a high GI food by having it with a low GI food.

The only time I think about the GI index is in relation to specific foods eg if I’m choosing a type of rice.

I never really look at the carbs per 100g as it’s the carbs per portion that’s relevant, so I don’t really think it’s deceptive.

 

[trophywench]

Even then @Inka - portion size is entirely individual. I mean it's easy when things come in ones - like a packet of Ryvita or sliced bread - but define a serving of cooked rice. Is your portion likely to be exactly the same weight/volume as mine? Doubt it!

 

[Nayshiftin]

I tried this and was getting crazy blood sugars that did not tie up. Yes I agree certain foods set sugars high but it might not be what you eat. Being I’ll with infections and things raise my blood sugar . Being dehydrated raises my blood sugar Lazing about also affects it . So it’s not just about what we eat . Everyone’s good GI products are different . I find too much of anything is a no no . So it’s portion control and being able to cope with whatever life throws at me . The best thing Is keep an eye try not to go too low and supply your need appropriately and if too high cut back but seek help where needed. For some low carb works for others they do need help with meds n insulin. There is no shame whatever. I hope . After all we need to do what is right for us . Have a good day

 

[IrvineHimself]

Thanks everybody, you have completely confirmed my suspicions that the GI is an interesting concept, useful as a third, or even fourth, order consideration, but not normally of direct practical use.

.... You also need to keep your wits about you when looking a carb content of foods....

I completely agree

..... The things you quote in your list are all manufactured goods and a carb content can be sensibly quoted although you need to be aware that the regulations do not require the manufacturers to measure carb content, a reasonable estimate is acceptable. When it comes to fresh foods things get more difficult. You will, for example, find a carb value quoted for apples in standard tables. What you will not find is the variation between varieties, degree of ripeness and time in storage, all of which will affect the carb content.....

Again, I completely agree, the example list was chosen to highlight just one of the many potential pitfalls inherent in using a database of this form. In addition to "the variation between varieties, degree of ripeness and time in storage", cooking time and method of cooking also greatly affect the carb content, as does the source farm/orchard; the time of harvesting; .... and so on; and so on.

Bearing all this in mind, I am still finding compiling the database a useful exercise. It is giving me real practical insights into what my diet should look like.

I used to use this database (https://glycemicindex.com/) as I found it the most comprehensive.

Thanks, I will have a look at that link


Thanks to all for the comments
Irvine

 

[Burylancs]

Reliable GI data, and is it worth effort?

When I next have some surplus cash, I intend to buy a cheap set of kitchen scales. In anticipation of this, I have been putting together a database of nutritional info supplied by the Sainsbury's website. (This is not a recommendation with regard to price/quality, it is just a convenient source of consistent, reliable data)

Along with comparison products, it is focused on the things/brands I am likely to buy. Already, even without the scales, it is not only giving me a deep insight into what should and should not be in my diet, but highlighting things that are not immediately obvious. For example: The effects of cooking on calorie content, or the fact that the data for the normalised 100g sample is potentially misleading.

Example: How the normalised carbs/100g data can be misleading

Product​	Carbs per 100g​	Carbs per slice​
Byg Rice Cakes​	81.5​	6.1​
Ryvita Original​	77.5​	3.9​
Ryvita Dark Rye​	66.6​	6.7​
Oatcakes​	55.4​	5.6​
White Bread​	45.6​	18.2​
Brown Bread​	36.7​	14.7​

Anyway, I was thinking about adding GI data, but can't find a reliable, easily referenced source and was wondering if:

1. If you can recommend a source for the Gi of common supermarket products; vegetables,; meat and meat substitutes; dairy products; cereals and breads... etc?
2. Noting that the number of grams of carbohydrate in a food can have a bigger impact on blood sugar levels than the glycemic index does and actual increases in blood glucose show considerable variability from person to person. is it worth the effort of including the GI data?

I would be grateful to hear your thoughts
Irvine

The Sydney University website on GI based on Prof. Brand's work is a good source on GI. But attention has switched from the raw GI to the Glycemic Load. Perhaps better work out GL for the portions of carbs you are eating.

 

[IrvineHimself]

...But attention has switched from the raw GI to the Glycemic Load. Perhaps better work out GL for the portions of carbs you are eating.

Yeah, I noticed that in the Wikipedia page I referenced above. Thanks foe the link, it is useful

....- portion size is entirely individual.....

....I find too much of anything is a no no . So it’s portion control and being able to cope with whatever life throws at me....

I completely agree, with both of you. it is portion controls all the way. This is why I was so anxious to get a set of digital scales which can measure small quantities of a few grams to a kilogram or more.

You may be pleased to know that, (yesterday,) I did manage to get a set of reasonably decent quality scales. They cost me £10, which for me, is a significant outlay. But, I think they will prove to be well worth the expense.

For other newbies following along:
For me, getting into the habit of looking at nutritional info and interpreting what it means in terms of my diabetes was proving to be a real struggle. Spending an hour each day manually scraping the data is really helping me understand the carb content of various foods, along with the importance of portion control.

It does not need to be anything fancy. Modern spreadsheets like LibreOffice Calc, are actually powerful relational databases, which come with a comprehensive suite of database tools and wizards preinstalled. There are literally tens of thousands of hours YouTube instructional videos on how to filter and sort your data in Calc. So, if you decide to give it a try I would strongly suggest adding a tag field to each record like so

Group​	Tags​	Food Item per 100g​	Energy (kJ)​	Fat Total​	Fat Saturated​	Carbs Total​	Carbs Sugar​	Fibre​	Protein​	Salt​
Veg​	Bulk; Grain;​	Pasta​	675​	0.7​	0.1​	32.3​	1.6​	1.4​	5.2​	0.0​
Veg​	Bulk; Grain;​	Brown Rice​	720​	2.0​	0.3​	32.2​	0.5​	5.3​	3.3​	0.1​
Veg​	Bulk; Grain;​	Basmati Rice​	604​	1.2​	0.2​	29.5​	0.5​	0.9​	3.0​	0.2​
Veg​	Bulk; Veg;​	Potato​	349​	0.5​	0.1​	18.0​	0.8​	1.6​	1.8​	0.0​
Veg​	Bulk; Veg;​	Sweet Potato​	364​	0.5​	0.2​	17.2​	13.7​	2.5​	2.0​	0.1​
Veg​	Veg; Season; Salad;​	Garlic​	442​	0.6​	0.1​	14.8​	1.4​	4.1​	7.9​	0.0​

LibreOffice also has a number of tools that allow you to transpose and format copy/pasted tables, see YouTube, so with a bit of experience, the entire process becomes a couple of mouse clicks.

All the best and thanks for your help
Irvine

Edit
Note: As pointed out above, the precision of the quoted figures implies a false sense of accuracy. Comparing data from various sources, I wouldn't rate company website data with an accuracy greater than 15%, and that is probably being overly generous. However it still gives a useful indication of the relative carb content of various foods, along with how they relate to alternative choices.

 

[Docb]

Just seen your edit, @IrvineHimself. Absolutely spot on - just found a site where basmati rice was quoted at 52 g/100g Implied precision when quoting numbers is one of the things that I get on my hobby horse about. For example, I only quote one off meter readings to the nearest whole number!

By the way, I have an old version of microsoft software and use Excel and Access to keep track of my data but there is no way I would pay anything to microsoft to get them updated. For that reason I also do some things on the Libre Office suite just to find out how they compare so that I can migrate if I have to. Not yet got the hang of Libre Office Base but Calc is quite useable although a bit clunky when you have been used to Excel.

 

[Eddy Edson]

Not yet got the hang of Libre Office Base but Calc is quite useable although a bit clunky when you have been used to Excel.

That's a worry! (Coming from somebody who wishes Excel was a sentient being so that it could be punished for being always disappointing when you most need to rely on it).

@IrvineHimself dunno if you would find this useful www.cronometer.com but it's free & it links to the USDA food databses augmented with user additions, probably as comprehensive as anything else out there. Anyway, I started using it after I noticed nutrition science people I follow on twitter using it.

 

[IrvineHimself]

.... Implied precision when quoting numbers is one of the things that I get on my hobby horse about....

I don't generally get on my hobby horse about implied precision, though there have been more than a few instances of outright laughter. My favourite is when senior national politicians make speeches promising "full employment" without any caveats. This is a ludicrous thing for someone asking to be put in charge of the country to say: Inflation is directly tied to wage growth, and, as a result, to talk about "full employment" without specifying the "natural rate of unemployment" is meaningless. For example, in the 60's and early 70's, policy makers had a target figure of about 3% for the NROU, but in the 80's with the advent of monetarism, this figure was re-interpreted to be about 5% or more. That 2% difference equates to it being necessary for [roughly] an extra 600,000 people being unemployed in order to keep inflation in check.

... but Calc is quite useable although a bit clunky when you have been used to Excel.

That's a worry! (Coming from somebody who wishes Excel was a sentient being so that it could be punished for being always disappointing when you most need to rely on it).

Although functional they serve the same purpose, they are different products with their own fairly unique ways of doing things. So, while basic tutorials and techniques are generally interchangeable, the exact method of how best to achieve a desired outcome can vary significantly between the two products. As a heavy user of the LibreOffice suite, along with Gawk and the rest of the *nix tool set, I have never come across anything in Excel that I couldn't do in Calc, You just need to think about the problem in a manner more suited to the product you are using.
Irvine