News and Reviews

The naturally low GI spud story. 
Everyone loves potatoes but they are often very high GI and a problem when managing BGLs. Back in 2007, when Prof Jennie Brand-Miller and Dr Alan Barclay saw the evidence mounting that it is the potato variety that effects glycemic impact not the cooking method, they sat down with potato expert Graham Liney, grower Frank Mitolo and Dutch potato breeding company Agrico to put a low GI potato on the table. Three years after the first crop was pulled from the soil, the not-so-humble Carisma was internationally certified as the first low GI potato (GI 55). They were developed from conventional plant crossings with other potato varieties and tested in field trials in Australia.
 Kai Lin Ek
 Kai Lin Ek, Accredited Practising Dietitian

Presenting at the International Congress of Nutrition in Granada in September 2013, Sydney University researcher Kai Lin Ek reported her findings that showed that Carisma ‘not only ranks well alongside other potatoes, but is also comparable with other low GI foods. Potatoes tend to get bad press because they are generally classified as a high GI carbohydrate but our research has discovered that Carisma has half the blood glucose response compared to other potato varieties,’ she said. ‘It has a similar GI to pastas, all of which are usually classified as low GI foods. But don’t overcook it. Any starchy carbohydrate has a higher GI if it is overcooked. If rice is mushy or pasta is not al dente you just increase the starch digestibility. Boiling for about nine minutes is the ideal cooking time to enjoy the health benefits and flavours of Carisma.’

Carisma potatoes

Developing a screening method for identifying further low GI potato cultivars is a health and agricultural priority. In a follow-up study published in the British Journal of Nutrition Kai Lin Ek reports that low GI potato cultivars could be identified by in vitro screening. In this study of seven potato cultivars she concludes, we found that: ‘GI values were strongly and positively correlated with the percentage of in vitro enzymatic hydrolysis of starch in the cooked potatoes. Amylose, dietary fibre and total starch content was not correlated with either in vitro starch digestibility or GI.’ Carisma potatoes are now grown all over Australia, and they are now in the ground in North America and Europe, so they will be commercially available in those regions in the near future.

Let’s put the GI facts on the table so consumers can make healthier choices. 
‘GI methodology is accurate and precise enough for practical use; GI is a property of foods; and GI is biologically meaningful and relevant to virtually everyone,’ writes GI pioneer Prof Tom Wolever in the European Journal of Clinical Nutrition addressing current criticisms that focus on GI’s validity. ‘None of the critics provide sound reasons for rejecting GI because some of their arguments are based on flagrant errors in understanding and interpretation while others are not supported by current data or are inconsistent with other nutritional recommendations.’

Wolever is concerned that current dietary guidelines recommend increased consumption of whole grains and dietary fibre, but do not mention GI. ‘This is illogical,’ he says ‘because the evidence that GI affects health outcomes is at least as good, or better, than that for whole grains and fibre. GI is a novel concept from a regulatory point of view and a number of problems do need to be addressed to successfully translate GI knowledge into practice. The problems are not insurmountable but no progress can be made until bias and misunderstanding about GI can be overcome and there is better agreement about what is the actual state of knowledge on GI so that the real issues can be identified and addressed.’ Speaking to GI News, Tom Wolever says: ‘I have nothing against recommending people consume more fiber and whole grains, my concern here is that these are not better markers of carbohydrate quality than a food's GI value.’ 

Bill Shrapnel on why sugar intake from soft drinks is falling.

Bill Shrapnel
Bill Shrapnel, Accredited Nutritionist

‘Carbonated soft drinks have been a major source of sugar in the Australian diet for decades. In 2007, Dr Gina Levy and Professor Linda Tapsell published an analysis of sales of soft drinks and other water-based beverages in Australia between 1997 and 2006. There were three key findings – beverage sales were increasing; there was a shift away from sugar-sweetened to non-sugar drinks; and the per capita contribution of sugar from these beverages to the national diet was declining. Recently, Gina Levy and Bill Shrapnell conducted a study to update the earlier findings of Levy and Tapsell. Their objective was to assess trends in sales of soft drinks and other water-based beverages over a 15-year period, from 1997 to 2011. The paper has been accepted for publication in Nutrition and Dietetics and Gina Levy presented their findings at the ‘Sweet Symposium’ in Sydney on 2 December 2013. The most interesting finding from this study was the fall in the sugar contribution from carbonated soft drinks from 8.4kg (about 18 pounds) per person in 1997 to 6.2kg (about 13 pounds) per person in 2011. In relation to the broader category of sugar-sweetened beverages, per capita sugar contribution fell over the 15-year period from 9.2kg (about 20 pounds) to 7.6kg (about 16½ pounds). The reason for the decline in the contribution of sugar from these beverages is the ongoing, long-term decline in the proportion that is sugar-sweetened, from 70% to 58% of the total. This is largely driven by a substantial shift in carbonated soft drinks from sugar-sweetened to non-sugar drinks. Over 15 years the proportion of carbonated soft drinks that is sweetened with sugar has fallen from 64% to 45% of the total. There has been a corresponding increase in the proportion of non-sugar soft drinks (e.g. diet soft drinks with non-nutritive sweeteners) and still water. The traditional drivers of the soft drink market have been indulgence and convenience. It now appears as though increasing health consciousness, especially in relation to body weight, is making its presence felt.’ To read more, head over to The Sceptical Nutritionist. (Reprinted with permission).

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Reviewing the role of fructose, sucrose, and HFCS in diabetes.  
‘There remains a lack of consistent evidence to suggest that fructose, sucrose, or HFCS at moderate doses is directly related to the development of diabetes and other cardio-metabolic diseases, although there is potentially cause for concern where fructose is provided at high doses or contributes excess energy to diets’ write Drs John Sievenpiper and Al Cozma in US Endocrinology. But ‘many questions remain unanswered,’ they say. ‘High-quality trials are needed to assess the role of fructose-containing sugars in free exchange with foods likely to replace them in the diet in the development of diabetes and cardio-metabolic diseases.’

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