Using the GI in pregnancy.
‘In the long run, excessive weight gain in pregnancy has contributed to the current epidemic of obesity in women and children,’ says Prof Jennie Brand-Miller in her new book, The Bump to Baby Low GI Eating Plan (Hachette Australia). ‘A woman who gains too much during pregnancy gives birth to an overweight daughter, who in turn is more likely to be an overweight child and young adult, who is then more likely to gain excessive weight during her first pregnancy and give birth to a child with excess fat, and the cycle repeats itself.’ In this issue, we report on two recent studies suggesting long-term benefits of mum-to-be switching to a low GI diet.
1) A diet with a high GL increases the risk of excessive weight gain during pregnancy and post partum weight retention according to the Danish study in the British Journal of Nutrition. ‘The associations varied with the mother’s pre-pregnancy weight, and were more pronounced among the overweight and obese women. Even though only a modest effect on birth weight was observed, attention should be paid to the fact that the quality of carbohydrate in the diet may affect the birth outcome,’ the authors concluded.
2) Women who switch to a low GI diet during pregnancy are 20% less likely to experience excessive weight gain concludes the British Medical Journal. ‘This type of excessive weight gain during pregnancy is associated with an increased need for delivery by Caesarean section, a higher likelihood of post pregnancy weight retention, and a higher predisposition to obesity in later life,’ according to lead author, Fionnuala McAuliffe, professor of obstetrics and gynaecology at the University College Dublin School of Medicine. The study found that the 400 mums-to-be who changed their eating habits to the low GI diet gained an average amount of 12.2 kg during pregnancy, while the remaining participants put on an average weight of 13.7 kg.
Commenting on the overall GI of the women’s diet in the BMJ study Dr Alan Barclay points out that the women only achieved a mean daily average GI of 56 (down from 57.3 at baseline) and the difference in GI between the control and intervention groups was small – 1.7 units. ‘I believe an overall low GI diet should have an average dietary GI of around 45. There’s pretty compelling evidence from population health studies and clinical trials around the world that for long-term health and wellbeing this is the sort of figure we should aim for. It’s not as hard as it sounds to achieve this (around a fifth of the world’s population do). Choose less processed food most of the time and take the “this for that” option, that is you simply substitute healthy low GI carbs for high GI ones when shopping, cooking and eating out’.
Discovering rice’s GI gene.
As we have explained in GI News over the years, the GI of rice (brown or white; black or red) depends on its amylose content– a kind of starch that resists gelatinisation. When you cook rice, millions of microscopic cracks in the grains let water penetrate right to the middle of the grain, allowing the starch granules to swell and become fully ‘gelatinised’, thus very easy to digest. Greater gelatinisation of starch means a higher GI. Some varieties of rice have lots of amylose; others much less. There’s no easy way to tell. Neither the colour nor the length of the grain is a guide to the GI.
A research team from the International Rice Research Institute (IRRI) and CSIRO's Food Futures Flagship has now published a study in Rice which analysed 235 varieties of rice from around the world. They found that the GI ranged from 48 to 92 in the varieties they looked at. Importantly, they also identified the key gene that determines the GI of rice – a very useful achievement which offers rice breeders the opportunity to develop low or lower GI varieties.
Check out our Rice salad with fennel, orange and chickpeas (from the Forks Over Knives -- The Cookbook in the GI News Kitchen.
Do nonnutritive sweeteners really help you lose weight?
The sugar veto for people with diabetes or wanting to lose weight has helped create a huge market for alternative sweeteners from Aspartame (Equal/Nutrasweet) to stevia. Nonnutritive sweeteners provide few calories (kilojoules), carbs or any other nutrient. Typically they are hundreds of times sweeter than sucrose (table sugar), so you only need a minute amount. However, so that you can use them in a similar way to sugar (eg by the teaspoon), the manufacturer usually adds a bulking agent such as maltodextrin.
Nonnutritive sweeteners have virtually no effect on blood glucose levels and can help you cut back on your calories if you use them to replace equivalent amounts of sugar or honey etc. Their major drawback is that they aren’t as versatile as sugar and honey (and other nutritive sweeteners) because they tend not to be heat stable, they don’t brown or caramelise and they don’t add texture or bulk to food when used in baking. Gram for gram, they also tend to be much more expensive than their counterparts.
Reviewing the evidence, a Scientific Statement from the American Heart Association and the American Diabetes Association in Diabetes Care concludes that ‘when used judiciously, nonnutritive sweeteners could facilitate reductions in added sugars intake, thereby resulting in decreased total energy and weight loss/weight control, and promoting beneficial effects on related metabolic parameters. However, these potential benefits will not be fully realized if there is a compensatory increase in energy intake from other sources.’ They make the additional point that ‘At this time, there are insufficient data to determine conclusively whether the use of nonnutritive sweeteners to displace caloric sweeteners in beverages and foods reduces added sugars or carbohydrate intakes, or benefits appetite, energy balance, body weight, or cardiometabolic risk factors. There are some data to suggest that nonnutritive sweeteners may be used in a structured diet to replace sources of added sugars and that this substitution may result in modest energy intake reductions and weight loss.’
Nuts and olive oil for health.
Spanish researchers Prof Jordi Salas Salvado and Dr Emilio Ros presented the results of the long-term PREDIMED diet study (PREvencion con DIeta MEDiterranea – Prevention with the Mediterranean Diet) at the International Congress of Dietetics in Sydney. This comprehensive review of the Mediterranean diet is now in its ninth and final year. Nearly 7400 older adults at risk of cardiovascular disease, but with no symptoms, were randomly assigned to one of three diets (followed for five years on average). The three diets were:
- Mediterranean diet enriched with 30g (1oz) of mixed nuts per day (15g walnuts, 7.5g almonds, 7.5g hazelnuts)
- Mediterranean Diet enriched with virgin olive oil – 1 litre (4 cups) per family per week or 50ml (a little over 1½ fl oz) per day per study participant
- Low fat control diet – avoidance of plant and animal fats.
- reduce the risk of diabetes by 52%
- reduce the risk of metabolic syndrome by nearly 14%
- reduce blood glucose levels, systolic and diastolic blood pressure and the LDL:HDL cholesterol ratio
- improve biomarkers of inflammation
- reduce obesity measures, such as BMI and waist circumference.
