1 March 2009

Curly Questions

If, say, one eats a high GI meal, how much lemon juice needs to be consumed to bring the reading down to low GI? I am not at all suggesting this as a way of life, but I want to understand how I can overcome a problem, if it comes up.
Research findings over the past decade have indicated that a realistic amount of lemon juice or vinegar just as a salad dressing eaten with a mixed meal has significant blood glucose lowering effects. For example, as little as 1 tablespoon of lemon juice or vinegar in a vinaigrette dressing (with 2 teaspoons of oil) with an average meal lowered blood glucose by as much as 25-30%.


I have heard that Brewer’s yeast is a good source vitamin B. What are the benefits? Are there any pitfalls I should be aware of? (I have reduced my blood glucose levels by losing a considerable amount of weight.)
Dietitian Nicole Senior says: ‘Brewer’s yeast is simply a natural source of B vitamins, as well as some other nutrients. It is the dead yeast left over after brewing beer. It will have no adverse impact on your weight loss and blood glucose results. You could also source the nutrients you get from Brewer's yeast in yeast-extract spreads such as Vegemite or Marmite (acquired tastes and they are high in sodium). Brewer’s yeast also contains small amounts of other nutrients such as chromium (which may assist in blood glucose control), selenium, zinc, phosphorous and magnesium.’

Email your curly question about carbs, the GI and blood glucose to: gicurlyquestions@gmail.com


Richard & Kim said...

Am I reading this right? If I had a tablespoon of lemon juice with a meal I will see a reduction of my glucose level of 25%? I do not understand? If this were the case why wouldn't our health care team tell us to do this regularly?

GI Group said...

Health care providers are not always aware of all the science out there. Perhaps too, they want to see whether it makes a difference, not just acutely (ie with a meal in a test setting), but over the longer term. We aren’t aware of anyone doing a longer term study (eg a few weeks at least). If you want to check out the studies so far, Google ‘pubmed vinegar reduces glycemic response’ or something similar. Here’s the abstract of a study we reported in GI News back in 2005.

Vinegar dressing and cold storage of potatoes lowers postprandial glycaemic and insulinaemic responses in healthy subjects. Leeman M, Ostman E, Björck I.

OBJECTIVE: To investigate the effects of cold storage and vinegar addition on glycaemic and insulinaemic responses to a potato meal in healthy subjects. SUBJECTS AND SETTING: A total of 13 healthy subjects volunteered for the study, and the tests were performed at Applied Nutrition and Food Chemistry, Lund University, Sweden.Experimental design and test meals:The study included four meals; freshly boiled potatoes, boiled and cold stored potatoes (8 degrees C, 24 h), boiled and cold stored potatoes (8 degrees C, 24 h) with addition of vinaigrette sauce (8 g olive oil and 28 g white vinegar (6% acetic acid)) and white wheat bread as reference. All meals contained 50 g available carbohydrates and were served as a breakfast in random order after an overnight fast. Capillary blood samples were collected at time intervals during 120 min for analysis of blood glucose and serum insulin. Glycaemic (GI) and insulinaemic indices (II) were calculated from the incremental areas using white bread as reference. RESULTS: Cold storage of boiled potatoes increased resistant starch (RS) content significantly from 3.3 to 5.2% (starch basis). GI and II of cold potatoes added with vinegar (GI/II=96/128) were significantly reduced by 43 and 31%, respectively, compared with GI/II of freshly boiled potatoes (168/185). Furthermore, cold storage per se lowered II with 28% compared with the corresponding value for freshly boiled potatoes. CONCLUSION: Cold storage of boiled potatoes generated appreciable amounts of RS. Cold storage and addition of vinegar reduced acute glycaemia and insulinaemia in healthy subjects after a potato meal. The results show that the high glycaemic and insulinaemic features commonly associated with potato meals can be reduced by use of vinegar dressing and/or by serving cold potato products.

Ann Rockley said...

I would really like GI News to stop using terms like "lowers blood glucose" and instead say reduces post prandial rise in blood glucose, or something of that nature. I am a severe reactive hypoglycemic, not pre-diabetic, and not overweight and spend a great deal of time ensuring that I keep my blood sugars balanced. Some foods do in fact lower blood sugar/blood glucose causing a sometimes severe reaction (e.g., raw garlic in tzatziki). I never know which it is. I want to reduce the increase in blood glucose after a meal I do not want to lower my blood glucose. I have made myself quite ill a couple of times incorrectly interpreting the results of some foods and supplements.

It is clear what you meant from the response to these comments, it is not clear what you meant in the article.

Thank you.

GI Group said...

Hi there Ann, thanks for taking the time to post your comment. We will certainly keep the point you raise in mind in our stories.

na said...

So,what about cooling boiled pasta for 24 hours then adding to it the chosen sauce,do we enjoy a lower GI meal by this way? and what about heating the cooled potato before eating,is it still leading to less GI by 43%? finally what about the frozen pizza crust, is it of less GI? THNKS for the answer.

Na said...

Hi,why I am getting no answer for my question? thanks

GI Group said...

Sounds to us like you need to get hold of a copy of one of Prof Jennie Brand-Miller's books. Most of your questions will be answered in The Low GI Handbook (The New Glucose Revolution in the US).

Al dente cooked pasta has a low GI. There's no need to cool and reheat it. And we haven't seen any test results for it treated this way. Keeping portions moderate is the key here. And of course reheating may end up overcooking it and a higher GI.

As for potato, there aren't published GI results for reheating cooled potato. Enjoy it cold as potato salad and keep portions moderate. That means the equivalent of one medium spud.

Fresh or frozen, pizza crust is made from refined flour. The problem generally with pizza is too much saturated fat (all that cheese)and too many calories.