1 August 2008

GI News—August 2008


  • Fruit juice and diabetes risk
  • Turmeric’s blood glucose benefits
  • Can you worry the weight off?
  • Low GI diet reduces cancer risk
  • Will jelly beans at half time give sporty kids more energy?
  • GI News Chinese edition launched
This month, as GI News heads into its fourth year with 50,000 plus subscribers, Prof Jennie Brand Miller sets out the key to eating a low GI diet and Susie Burrell begins a new series for Healthy Kids sharing some practical lessons she has learned as a specialist paediatric dietitian. On the food front, spice supremos Ian and Liz Hemphill share their recipes that make the most of turmeric and Catherine Saxelby checks out cranberries, sorting the health from the hype. Of course there are the usual features including our popular Success Stories and feedback where we answer your Curly Questions about carbs, the GI and blood glucose.

Good eating, good health and good reading.

GI News Editor: Philippa Sandall
Web Design and Management: Scott Dickinson, PhD


RickH said...

Not sure where to ask questions, so I'll do it here.
I'm interested finding out how accurate calories are as a measure for food energy. As far as I can see, it refers to burning an item to see how much energy it releases, then applying some efficency factor to apply to human digestion.
For such a commonly used term, it's not very meaningful. Has anyone calibrated the calorie with actual human test subjects as the GI tests are done?
Everyone digests food differently, sometimes greatly. A fair amount of ingested alcohol is directly excreted through urine and sweat, is that figured in the calorie count?
After all, we don't have fires burning in our bodies for energy...

GI Group said...

We think this is a great question and are working on an answer for you Rick. Check back in a couple of days.

GI Group said...

We flicked this one to dietitian Dr Alan Barclay to get the ball rolling as there are sure to be lots of comments.

‘It’s an excellent question,’ said Alan, ‘and one I often pose to calorie fans! The Atwater factors (http://en.wikipedia.org/wiki/Atwater_system) which we use for the macronutrients were done in the early part of last century. They were based on work with bomb calorimetry (http://en.wikipedia.org/wiki/Calorimeter), with factors applied. At best they are approximations for all of the reasons Rick has listed and more …’

For a bit of background, you might like to continue your own research and check out the following article (it's available in full online).

Does the history of food energy units suggest a solution to "Calorie confusion" http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2238749
Here’s what the abstract says to whet your appetite:

“The Calorie (kcal) of present U.S. food labels is similar to the original French definition of 1825. The original published source (now available on the internet) defined the Calorie as the quantity of heat needed to raise the temperature of 1 kg of water from 0 to 1°C. The Calorie originated in studies concerning fuel efficiency for the steam engine and had entered dictionaries by 1840. It was the only energy unit in English dictionaries available to W.O. Atwater in 1887 for his popular articles on food and tables of food composition. Therefore, the Calorie became the preferred unit of potential energy in nutrition science and dietetics, but was displaced when the joule, g-calorie and kcal were introduced. This article will explain the context in which Nicolas Clément-Desormes defined the original Calorie and the depth of his collaboration with Sadi Carnot. It will review the history of other energy units and show how the original Calorie was usurped during the period of international standardization. As a result, no form of the Calorie is recognized as an SI unit. It is untenable to continue to use the same word for different thermal units (g-calorie and kg-calorie) and to use different words for the same unit (Calorie and kcal). The only valid use of the Calorie is in common speech and public nutrition education. To avoid ongoing confusion, scientists should complete the transition to the joule and cease using kcal in any context.”

Unknown said...

When I was on the Atkins diet (and lost 25 lbs which I kept off for 3 years) it was clear how much of what I was allowed to eat. What I find difficult with the Low GI diet is that it says nothing about how much of one food is equivalent to how much of another. In fact the Index is not calibrated for quantity at all, which leaves me puzzled as to whether I am or am not following the diet!

hermin said...

it seems that you prefer a prescriptive diet (with detailed instructions) rather than general
principles which allow more freedom and flexibility.

my view is that the healthy eating guide (either in the form of a pyramid/plate/circle) is a great
tool to determine the quantity, i.e. how much bread/cereal/pasta we should eat.

GI, on the other hand, is especially useful in terms of quality. That is, GI helps you choose the best food within a food group, or the best choice among similar foods. So, having known HOW MUCH starchy food you need to eat, you can use GI to choose WHAT to eat most often.

e.g. Basmati rice has a lower GI than most other types of rice, so i would pick it as my "rice of choice".

so, i think, it's best to combine the GI principles with your country's healthy eating guide.

hope this helps :)

GI Group said...

Here’s what Dr Joanna McMillan Price says:
‘You’ve actually pointed out a key difference between the low GI way of thinking and most other “diets”. It may take a while to get used to and adjust your mindset, but we see this as a huge advantage for long term success. It is not about weighing, measuring and counting food, but rather about choosing the best quality foods that will work with your body. The GI ranking of foods actually tells you that for the same amount of carbohydrate, the actual effect on your blood sugars, and subsequently your insulin levels, can be wildly different. In order to best use the GI as a tool towards a better diet, think of swapping ‘like’ foods for a lower GI version – eg muesli instead of a processed high GI breakfast cereal, low GI wholegrain bread over white, and wholegrains such as barley or quinoa over high GI rice or potatoes. You are aiming to have most if not all of the major carbohydrate-rich foods in your diet - pasta, rice, bread, breakfast cereal, potatoes – swapped for a low GI choice. If you achieve that you will find that you are more satisfied with your meals, less hungry between meals, have more energy for exercise and ultimately lose weight (as fat) more easily. In essence it is hard to overeat the healthy low GI foods as they are more filling (this doesn't apply to foods like ice cream and chocolate!). The essence of a healthy diet is first and foremost to eat the right foods – the GI is a tool to help to do just that. Quantities of food will naturally follow after that as you learn to listen to your appetite.’

GI Group Adds: The Low GI Diet by Prof Jennie Brand-Miller et al has a 12-week action plan with a special section on how much food is right for you plus 10 different weight-based energy levels to give you the number of serves of protein-rich and carb-rich foods plus the good fats you need each day for wellbeing and weight loss.