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Emerging Science

The science of GI is evolving into other areas where scientists are seeing the benefits of eating a low GI diet to either manage, improve on or prevent certain conditions. This includes the areas of cognitive performance, skin health, reducing the risk of some cancers, improved eye health, managing gestational diabetes and PCOS symptoms.


Improve cognitive performance.

Low GI foods provide a steady supply of fuel (glucose) to the brain, improving cognitive performance.

Supporting scientific papers:


Breakfast glycaemic index and exercise: combined effects on adolescents’ cognition.

This study investigated the combined effects of breakfast GI and exercise on adolescents cognitive function. A low GI breakfast and mid-morning bout of exercise were individually beneficial for response times on the Sternberg paradigm (a memory test), whereas they conferred additional benefits for response times on the Stroop test (a test of attention). Cooper et al, Physiol Behav. 2015 Feb;139:104-11


Glycaemic index and glycaemic load of breakfast predict cognitive function and mood in school children: a randomised controlled trial. 

This study investigated the effects of meals differing in glycemic index and glycemic load on cognition and mood in school children.  It was found that low GI meals predicted better declarative-verbal memory with the overall conclusion being that the low GI high GL breakfast may help to improve learning. Micha et al. Eur J Clin Nutr 2010; 64(9):948-57.


A low glycaemic index breakfast cereal preferentially prevents children’s cognitive performance from declining throughout the morning.

This study found that children’s performance declines throughout the morning and that this decline can be significantly reduced following the intake of a low GI breakfast cereal as compared with a high GI cereal. Ingwersen et al. Appetite 2007; 49(1):240-4.


The influence of the glycaemic load of breakfast on the behaviour of children in school.

This study found that two to three hours after a low glycemic load breakfast had been consumed, performance on the tests of memory and the ability to sustain attention were better, fewer signs of frustration were displayed and initially more time was spent on task when working individually in class. Benton et al. Physiol Behav 2007; 92(4):717-24.


Reduce acne.

High insulin levels that result from eating high GI foods are associated with acne and a low GI diet can help improve acne by regulating insulin imbalance.

Supporting scientific papers:


Diet and acne: a review of the evidence.

One prospective cohort study demonstrated an association between high glycemic index foods and longer acne duration, whereas two randomized controlled trials demonstrated that a low glycemic index diet reduced acne risk. Spencer et al. International Journal of Dermatology. 2009; 48: 339–347


Decrease the risk of some cancers.

Studies have shown that eating a low GI diet can reduce your risk of developing some cancers.

Supporting scientific papers:


Glycaemic index and glycaemic load in relation to risk of diabetes-related cancers: a meta-analysis. 

Thirty-six prospective cohort studies with a total of 60,811 cancer cases were included in the meta-analysis. In a comparison of the highest and lowest categories, the relative risks of all cancers were 1·07 (95 % CI 1·04, 1·11) for GI and 1·02 (95 % CI 0·96, 1·08) for GL. In an analysis of site-specific cancer risks, significant associations were found for GI in relation to breast cancer (RR 1·06; 95 % CI 1·02, 1·11) and colorectal cancer (RR 1·08; 95 % CI 1·00, 1·17). GL was significantly associated with the risk of endometrial cancer (RR 1·21; 95 % CI 1·07, 1·37). In conclusion, there is a modest-to-weak association between a diet that induces a high glycemic response and cancer risks. Choi et al. Br J Nutr. 2012;108(11):1934-47


Dietary glycemic index and glycemic load and risk of colorectal cancer: results from the EPIC-Italy study. 

This study investigated dietary glycemic index and glycemic load, in relation to colorectal cancer, in the prospectively recruited EPIC-Italy cohort. After a median 11.7 years of follow up, 421 colorectal cancers were diagnosed among 47,749 adults. The adjusted hazard ratio of colorectal cancer for highest versus lowest GI quartile was 1.35 (95%CI 1.03-1.78). Increasing high GI carbohydrate intake was also significantly associated with increasing colorectal cancer risk (1.45; 1.04-2.03), whereas increasing low GI carbohydrate was associated with reducing risk (0.73; 0.54-0.98). High dietary GI and high GI carbohydrate were associated with increased risks of cancer at all colon sites (1.37; 1.00-1.88, 1.80; 1.22-2.65). These findings suggest that high dietary GI and high carbohydrate intake from high GI foods are associated with increased risk of colorectal cancer. Sieri et al. Int J Cancer. 2015 Jun 15;136(12):2923-31


Eye health.

Growing evidence suggests that a healthy low GI diet can prevent age-related macular degeneration (AMD), a leading cause of blindness in Australia. High GI diets have been associated with an increased risk of early onset AMD.

Supporting scientific papers:


Dietary hyperglycemia, glycemic index and metabolic retinal diseases.

This review suggest that while management of dietary GI appears to be an effective intervention for the prevention of metabolic diseases such as age-related macular degeneration (AMD) and diabetic retinopathy, more interventional data is needed to evaluate the efficacy of GI management in the prevention of these conditions Chiu et al, 2011, Prog Retin Eye Res. 2011 Jan;30(1):18-5


Does eating particular diets alter the risk of age-related macular degeneration in users of the Age-Related Eye Disease Study supplements?

The Age-Related Eye Disease Study (AREDS) provided supplements of the essential fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and reduced dietary glycemic index and found that the regimen was protective against advanced age-related macular degeneration (AMD). Chiu et al. Br J Ophthalmol. 2009 Sep;93(9):1241-6


Dietary glycemic index and the risk of age-related macular degeneration.

A high glycemic index diet is a risk factor for early age-related macular degeneration (AMD) – the recognized precursor of sight-threatening late AMD. Low glycemic index foods such as oatmeal may protect against early AMD.  Kaushik et al. Am J Clin Nutr. 2008; 88(4):1104-10.


Gestational Diabetes Mellitus (GDM).

Low GI diets are associated with less frequent insulin use and lower birth weight than in control diets, suggesting that it is the most appropriate dietary intervention to be prescribed to patients with GDM.

Supporting scientific papers:


Randomized Controlled Trial Investigating the Effects of a Low–Glycemic Index Diet on Pregnancy Outcomes in Women at High Risk of Gestational Diabetes Mellitus: The GI Baby 3 Study. 

The authors compared the effect of a low glycemic index versus a conventional high fibre (HF) diet on pregnancy outcomes, birth weight z-score, and maternal metabolic profile in women at high risk of gestational diabetes (GDM). In intensively monitored women at risk for GDM, a low GI diet and a healthy diet produce similar pregnancy outcomes. Markovic et al. Diabetes Care, 2015.


Carbohydrates, glycemic index, and pregnancy outcomes in gestational diabetes. 

The authors conclude that pregnant women with GDM are likely to benefit from following a low GI meal pattern, with no significant side effects, and consideration of the GI should be given when formulating a diet for GDM. However, until larger scale intervention trials are completed, an exclusive low GI diet should not replace the current recommended diets for GDM from relevant government and health agencies Louie JC et al. Curr Diab Rep. 2013 Feb;13(1):6-11.


Can a low-glycemic index diet reduce the need for insulin in gestational diabetes mellitus? A randomized trial. 

Using a low-glycemic index diet for women with GDM effectively halved the number needing to use insulin, with no compromise of obstetric or fetal outcomes. Moses et al. Diabetes Care, 2009; 32(6): 996-1000


Polycystic Ovarian Syndrome (PCOS).

PCOS affects up to 10 per cent of women of reproductive age and sufferers often develop a resistance to the hormone insulin.  Insulin is needed to keep blood glucose levels stable and when it doesn’t work properly weight gain often results.

Supporting scientific papers:


An isocaloric low glycemic index diet improves insulin sensitivity in women with polycystic ovary syndrome. 

This study involved a nonrandomized 12 week low GI dietary intervention, preceded by a 12 week habitual diet control phase and proceeded by a 12 week follow-up phase in 21 women aged 32.1 years (average). During the dietary intervention phase, dietary GI decreased from 54.5 to 48.6 (P<0.001) with a concurrent small reduction in saturated fat intake (12.4% to 11.7% contribution from energy, P=0.03), despite no specific recommendations to modify fat intake. Measures of insulin sensitivity and nonesterified fatty acid improved after intervention (P=0.03 and P=0.01, respectively). Barr et al J Acad Nutr Diet. 2013 Nov;113(11):1523-31.


Dietary composition in the treatment of polycystic ovary syndrome: a systematic review to inform evidence-based guidelines. 

This systematic literature review found six articles from five studies that met a priori selection criteria, which included a total of 137 women, and determined that greater weight loss was achieved on a monounsaturated fat-enriched diet; improved menstrual regularity on a low-glycemic index diet; increased free androgen index for a high-carbohydrate diet; greater reductions in insulin resistance, fibrinogen, total, and high-density lipoprotein cholesterol on a low-carbohydrate or low-glycemic index diet; improved quality of life on a low-glycemic index diet; and improved depression and self-esteem on a high-protein diet. Weight loss improved the presentation of PCOS regardless of dietary composition in the majority of studies. Moran et al. J Acad Nutr Diet. 2013 Apr;113(4):520-45.


Beneficial effects of a high-protein, low-glycemic-load hypocaloric diet in overweight and obese women with polycystic ovary syndrome: a randomized controlled intervention study.

In this study both a conventional reduced kilojoule diet and a high protein, low GI diet led to reduced body weight and androgen levels in women with PCOS. The combination of high-protein and low glycemic load foods in a modified diet caused a significant increase in insulin sensitivity and a decrease in hsCRP level compared to the conventional diet. Mehrabani  et al, J Am Coll Nutr. 2012 Apr;31(2):117-25.


Effect of a low glycemic index compared with a conventional healthy diet on polycystic ovary syndrome.

In this study, overweight or obese premenopausal women with PCOS (n = 96) consumed either an ad libitum low GI diet or a macronutrient-matched healthy diet for 12 months or until they achieved a 7% weight loss. Compared with women who consumed the conventional healthy diet, more women who consumed the low GI diet showed improved menstrual cyclicity. Among the biochemical measures, only serum fibrinogen concentrations showed significant differences between diets. Marsh et al Am J Clin Nutr. 2010 Jul;92(1):83-92


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