 |
|
|
|
|
by Dr Jayashree Arcot and Prof Jennie Brand-Miller
March 2005
RIRDC Publication No 05/027 RIRDC Project No UNS-17A
Executive summary
Objective
To obtain a clear understanding
of the differences between the blood glucose responses of the different
sources of honey based on sugar and organic acid contents and identify
those varieties with low GI factor to use as a major marketing strategy
to increase consumption, especially in Diabetics.
Method
Initial discussions with
the Department of Agriculture, NSW were held to identify the common floral
varieties of honey that were available in 2001 depending on the season.
The relevant suppliers in Queensland, NSW, South Australia and Western
Australia were approached for the supply of honey with floral authentication.
Six floral varieties namely, Red Gum (E. camaldulensis), Salvation
Jane (Echium lycopsis), Ironbark (E. nubilis), Yellow Box
(E. melliodora), Stringybark (E. macrorhyncha) and Yapunyah
(E. ochrophloia) and two commercial blends were obtained from the
above suppliers.
When the samples were received in the laboratory, they were stored at -180C until further analyses.
Samples were analysed for their sugar contents, namely, fructose, glucose, maltose and sucrose and organic acids using standard HPLC techniques; and pH. The samples were tested for Glycemic Index and Insulin Index through a human study comprising at least 10 healthy individuals. Glycemic Index is a method developed in order to rank equal portions of different foods according to the extent to which they increase blood glucose levels after being eaten. On the basis of the available carbohydrate (sugars) content of the honeys, an amount of honey containing 25 grams of carbohydrate was given to each volunteer to eat after an overnight fast. Over the next two hours, finger prick capillary blood samples were collected and compared similarly with a reference food namely 25g bread. The Insulin Index was also studied using the same procedure in the same subjects except that the concentration of insulin in the plasma component was analysed instead.
Results and Discussion
The major results from the
study are that:
Outcomes
The results of this study
showed that different honeys could have significantly different effects
on blood glucose and insulin levels, due to differences in their sugar
content and physical form, and should not all be classified as one type
of food for people with diabetes.
Now armed with the knowledge that there are differences in the GI between the floral varieties of honey, and the fact that Yellow Box, Stringybark , Red Gum, Iron Bark and Yapunyah honeys were considered to be of low GI and Salvation Jane and a commercial blend (1) were of moderate GI, it should now be possible to better market these honeys as suitable for consumption in controlled amounts for the diabetics. Commercial blends may vary in their composition depending on the availability of honeys in that particular season and hence should be treated with caution if the varieties that have gone into the blend are unknown as GI will be variable too. From the consumers’ point of view, the floral varieties identified above with low to moderate GI should ideally be produced more and marketed better by the Honey Industry. There may be other floral varieties that may be available which should be studied in future for their GI.
|
