By Regina Belski, BNutrDiet (Hons), GradCertTertEd, PhD (UWA), APD, La Trobe University
What do you think of when you hear the word lupin? Pretty flowers? Stock feed? Well it’s time to change your thinking as lupin beans are a remarkably nutrient dense legume, which is finally being recognised for its exceptional properties and nutritional composition.
Lupin, is a legume grain, and has been eaten in many parts of the world for centuries. It is quite unique in its macronutrient composition, consisting of approximately 45% protein by weight and 30% dietary fibre, with negligible available carbohydrate. It can be eaten as a bean, or ground down into a flour, which can be substituted for wheat flour in baked foods such as breads to increase protein and fibre, and reduce refined carbohydrate content. Being a legume, it is also naturally gluten free.
Lupins have been grown in Australia for many years as part of crop rotation cycles with wheat, to put nitrogen back into the soil naturally, so lupins are a highly sustainable crop. For this reason Australia currently produces around 80% of the world’s lupin crop.
Scientists have only recently begun to explore the potential health benefits of lupins for human health. An acute study incorporating 40% Lupin flour into bread (compared to white bread) demonstrated that people felt fuller for longer and ate less at the next meal (Lee et al. 2006), suggesting regular consumption may lead to weight loss.
Both animal and human studies have also shown the significant impact of lupin on blood pressure. One study showed that a diet incorporating lupin flour-enriched bread compared to a white bread control led to significant differences in systolic blood pressure, diastolic blood pressure, and pulse pressure over the 16-week trial. Observed differences were 3.0, 0.6, and 3.5 mmHg, respectively (Lee et al 2009).
Another 12-month randomized controlled trial also explored blood pressure and observed that relative to control, the mean 24-h systolic and diastolic blood pressure in the lupin group was significantly lower (Belski et al. 2011). Given that just a 2-mmHg reduction in systolic blood pressure would translate to a 10% lower stroke mortality in middle-aged adults (Lewington et al., 2002), the notion of simply swapping the toast you eat in the morning to improve heart health is a tempting one.
Lupin grains have also reportedly been referred to as an antidiabetic product in traditional medicine (Terruzzi et al. 2011), and researchers have also observed benefits for blood glucose and insulin levels. Adding lupin flour to bread has been shown to reduce its GI (Hall et al. 2005). Lee et al. (2006 and 2009) have previously shown that lupin-enriched foods can acutely reduce postprandial glycemia and insulinemia. Belski et al. (2011) found that a lupin flour-enriched diet significantly lowered fasting insulin concentrations by 16% and 21%, and HOMA scores by 30% and 33% at 4 and 12 months, respectively. Dove et al. (2011) found that adding lupin to a carbohydrate-rich beverage reduces glycemia acutely in Type 2 diabetic inpiduals.
These results are exciting but more research is needed in this area. The food industry and manufacturers are finally starting to take notice, with a number of commercial products currently available and more being developed. This is an exciting space to watch, and an excellent example of using sustainable legumes that Australia has in abundance in improving the health of Australians!
1. Belski, R, et al. “Effects of lupin-enriched foods on body composition and cardiovascular disease risk factors: a 12-month randomized controlled weight loss trial.” International journal of obesity 35.6 (2011): 810-819.
2. Dove, E et al. “Lupin and soya reduce glycaemia acutely in type 2 diabetes.” British Journal of Nutrition 106.07 (2011): 1045-1051.
3. Hall, Ramon S., Sarah J. Thomas, and Stuart K. Johns. “Australian sweet lupin flour addition reduces the glycaemic index of a white bread breakfast without affecting palatability in healthy human volunteers.” Asia Pacific journal of clinical nutrition 14.1 (2005): 91-97.
4. Lee, Ya P., et al. “Lupin-enriched bread increases satiety and reduces energy intake acutely.” The American journal of clinical nutrition 84.5 (2006): 975-980.
5. Lee, Ya P., et al. “Effects of lupin kernel flour–enriched bread on blood pressure: a controlled intervention study.” The American journal of clinical nutrition 89.3 (2009): 766-772.
6. Lewington S, Clarke R, Qizilbash N, et al. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of inpidual data for one million adults in 61 prospective studies. Lancet 2002;360:1903–13.
7. Terruzzi, I., et al. “Insulin-mimetic action of conglutin-γ, a lupin seed protein, in mouse myoblasts.” Nutrition, Metabolism and Cardiovascular Diseases 21.3 (2011): 197-205.