Legumes - The Forgotten Weapons of Risk Reduction

While life expectancies have never been higher so too are rates of chronic diseases, resulting in large number of people living for many years with disease. Type 2 diabetes, heart disease and cancers are so common today that many may think these are inevitable. This could not be further from the truth. There is a multitude of dietary and lifestyle choices or “weapons of risk reduction” which individuals can adopt to add years to life and life to years. Legumes, an often forgotten food group, have huge potential as a weapon of risk reduction to fight off disease in the long term.

Lessons from the longest lived

In recent decades researchers have studied the longest lived communities around the world where a fraction of people suffer the diet and lifestyle related diseases which plaque many countries today. These unique regions around the world, known as “Blue Zones”, provide an insight into potential guidelines to achieve and maintain health as well as happiness over the lifespan. ⁽¹⁾   

“Blue Zones” include the Mediterranean regions of Sardinia in Italy and Icaria in Greece, as well as the islands of Okinawa, Japan; Loma Linda, California and the Nicoya Peninsula in Costa Rica. From studying these populations, researchers have identified universal themes fundamental to health and happiness. When it comes to diet, an overriding theme from these Blue Zones is an emphasis on legumes, such as beans, chickpeas, lentils and peas within a mostly plant-based diet.

When it comes to legumes, the traditional Sardinian diet is particularly high in fava beans, the Icarian’s enjoy a diet rich in chickpeas, kidney beans and lentils, the Okinawan people and seventh day Adventists of Loma Linda have high intakes of soy from beans, tofu and soy milk, whereas the people of the Nicoya Peninsula, Costa Rica eat a variety of beans with rice as a staple in their diet.   

This is not to say that legumes are the only foods contributing to health in these diets, which are also rich in fruits, vegetables, nuts and whole grains. However, the prominence of legumes in these populations is worthy of remark as legumes are a largely forgotten food group in Australia, with only 7% of us reporting to eat them in the latest National Nutrition Survey.⁽²⁾ 

In addition to learnings from the Blue Zones, the scientific evidence from populations all around the world (not just Blue Zones) consistently demonstrates that people who eat higher intake of legumes have better health outcomes including a significantly reduced risk of heart disease, some cancers, and improved blood glucose control.⁽⁴⁾

The potential of legumes

The benefits of diets that emphasise legumes are not surprising given their nutrient density – in fact in a recent analysis of the Australian Health Survey, people who ate legumes had higher total daily intakes of fibre (30.4 g vs 21.9g), protein, iron, magnesium, zinc, iodine and folate compared with non-consumers.(5) In addition to essential nutrients, legumes are also rich in protective phytonutrients which are likely to also contribute to the associated health benefits observed in long term consumers.

When it comes to Australian diets, the most recent National Nutrition Survey found that the majority of Australians (92.1% or almost 20 million people) did not eat legumes on either day of the survey.

So why don’t more people enjoy legumes? GLNC’s 2014 Grains and Legumes Consumption and Attitudinal Study found that the biggest barrier to legume consumption was simply that Australians do not think to include them in their diet or the meals they prepare.(2) As legumes are widely accessible and affordable there is lots of potential for Australians to improve their diet quality and reduce risk of disease in the long term by taking the simple step of enjoying legumes more often.

Starting this healthy habit

A good starting goal for those who don’t eat legumes regularly is to aim to eat a variety of legumes at least 2-3 times each week as part a balanced diet. This can easily be achieved by adding chickpeas or beans to your salads, choosing soy milk more often, enjoying hummus dip as a snack or simply adding a can of drained and rinsed canned beans/lentils to your favourite recipe (i.e. spaghetti with red lentils).

For more tips and tricks to help you, your friends or family start this healthy habit check out our family friendly cookbook An Everyday Guide to Cooking with Legumes as well as our Legumes - Start a Healthy Habit fact sheet.

References:

1. Blue Zones [cited 2015 March ]. Available from: http://www.bluezones.com/.
2. GLNC. 2014 Australian Grains and Legumes Consumption and Attitudinal Report. Unpublished: 2014.
3. NHMRC. Australian Dietary Guidelines: Providing the scientific evidence for healthier Australian diets 2013 [cited 2015 January]. Available from: http://www.nhmrc.gov.au/guidelines-publications/n55.
4. Fardet A, Boirie Y. Associations between food and beverage groups and major diet-related chronic diseases: an exhaustive review of pooled/meta-analyses and systematic reviews. Nutrition reviews. 2014:n/a-n/a.
5. GLNC. Secondary Analysis of the National Nutrition and Physical Activity Survey 2011-2012 Unpublished: 2014.

The Effect of Soluble Fibre Enrichment on Taste Perception - Preliminary Evidence

By Pridhuvi Thavaraj (PhD candidate) and Eugeni Roura PhD and Senior Researcher, University of Queensland

Researchers at the Queensland Alliance for Agriculture and Food Innovation at the University of Queensland (UQ) are investigating the fascinating area of the effect of fibre on the perception of taste. In this article, UQ scientists Pridhuvi Thavaraj (PhD candidate) and Eugeni Roura (Senior Researcher) explain the findings of their research on the effect of soluble fibre on our perception of taste.

Dietary fibres are believed to have a beneficial effect on human health related to weight management, diabetes, cardiovascular diseases and cancers among other conditions (Chawla & Patil, 2010). Due to this, they are in the forefront of many public health diet campaigns that urge a higher fibre intake. The current recommended adequate intake of dietary fibre is 25 - 30g/day (Department of Health and Ageing & Council, 2005). To meet this adequate intake, many everyday foods are being enriched with different types of dietary fibre (Al'absi, Nakajima, Hooker, Wittmers, & Cragin, 2012). However, how fibre enrichment in foods affects taste perception has not yet been systematically investigated.

Recent findings have provided further evidence that the sense of taste plays an important role in nutrient sensing and food intake (Chaudhari & Roper, 2010; Laffitte, Neiers, & Briand, 2014). Foods that have been enriched with fibres have been linked to decreased consumer preference (Laguna, Primo-Martin, Varela, Salvador, & Sanz, 2014; Yılmaz, 2005; Zahn, Forker, Krugel, & Rohm, 2013). The main changes observed in food after fibre enrichment are related to texture, appearance, and taste (Devereux, Jones, McCormack, & Hunter, 2003; Zahn et al., 2013). In addition, it is known that fibre enrichment decreases taste perception, however most of these conclusions have been drawn using liquid food models that are not representative of solid foods (Baines & Morris, 1987; Hollowood, Linforth, & Taylor, 2002).

In our current research we studied the interaction between dietary soluble fibres (Beta-Glucan and Pectin powders) and the sensitivity to sweet, bitter and umami tastes using a tasteless and non-nutritious solid food taste delivery model (chewing gum) using a procedure known as the forced-choice ascending concentration series method of limits for best estimation of thresholds or BET). BET refers to the amount of tastant (eg sugar) required for the detection of taste (Lawless, 2013). A lower threshold means that a lower amount of tastant is required for perception. Our study found that regardless of the treatment, both soluble fibres significantly (P<0 .001="">) decreased the BET for sweet, bitter and umami tastes while no impact on salty and sour tastes was observed.

These results suggest that soluble fibre enrichment of foods have the potential to enhance some of the tastes of solid foods when adequately manipulated. Consequently, our findings have the potential to design food formulations with less taste enhancers (eg sucrose) which may contribute to lower energy intake and a better control of weight gain.

References:

1. Al'absi, M., Nakajima, M., Hooker, S., Wittmers, L., & Cragin, T. (2012). Exposure to acute stress is associated with attenuated sweet taste. Psychophysiology, 49(1), 96-103. doi: 10.1111/j.1469-8986.2011.01289.

2. Baines, Z. V., &; Morris, E. R. (1987). Flavour/taste perception in thickened systems: the effect of guar gum above and below c*. Food Hydrocolloids, 1(3), 197-205. doi: http://dx.doi.org/10.1016/S0268-005X(87)80003-6

3.Chaudhari, N., & Roper, S. D. (2010). The cell biology of taste. The Journal of Cell Biology, 190(3), 285-296. doi: 10.1083/jcb.201003144

4.Chawla, R., & Patil, G. R. (2010). Soluble Dietary Fiber. Comprehensive Reviews in Food Science and Food Safety, 9(2), 178-196. doi: 10.1111/j.1541-4337.2009.00099.x

Department of Health and Ageing, & Council, N. H. a. M. R. (2005). Nutrient Reference Values for Australia and New Zealand, Including Recommended Dietary Intakes Retrieved 17/05/2014, from http://www.nrv.gov.au/sites/default/files/page_pdf/n35-dietaryfibre_0.pdf

5. Devereux, H. M., Jones, G. P., McCormack, L., & Hunter, W. C. (2003). Consumer acceptability of low fat foods containing inulin and oligofructose. Journal of Food Science, 68(5), 1850-1854. doi: 10.1111/j.1365-2621.2003.tb12341.x

6. Hollowood, T. A., Linforth, R. S. T., & Taylor, A. J. (2002). The Effect of Viscosity on the Perception of Flavour. Chemical Senses, 27(7), 583-591. doi: 10.1093/chemse/27.7.583

7. Laffitte, A., Neiers, F., & Briand, L. (2014). Functional roles of the sweet taste receptor in oral and extraoral tissues. Curr Opin Clin Nutr Metab Care, 17(4), 379-385. doi: 10.1097/mco.0000000000000058

8. Laguna, L., Primo-Martin, C., Varela, P., Salvador, A., & Sanz, T. (2014). HPMC and inulin as fat replacers in biscuits: Sensory and instrumental evaluation. Lwt-Food Science and Technology, 56(2), 494-501. doi: 10.1016/j.lwt.2013.12.025

9. Lawless, H. T. (2013). Psychophysics I Quantitative Sensory Analysis (pp. 1-23): John Wiley & Sons.

10. Yılmaz, I. (2005). Physicochemical and sensory characteristics of low fat meatballs with added wheat bran. Journal of Food Engineering, 69(3), 369-373. doi: http://dx.doi.org/10.1016/j.jfoodeng.2004.08.028

11. Zahn, S., Forker, A., Krugel, L., & Rohm, H. (2013). Combined use of rebaudioside A and fibres for partial sucrose replacement in muffins. Lwt-Food Science and Technology, 50(2), 695-701. doi: 10.1016/j.lwt.2012.07.026

High Prebiotic Diet Including Legumes

By Dr Jane Varney and Dr Jane Muir, Monash University

Maintaining a healthy balance of good and bad bacteria in your gut?

The human gut is home to trillions of bacteria. These bacteria are found in low numbers in the stomach and small intestine, with the majority residing in the large intestine. The gut naturally contains both harmful (pathogenic) and beneficial bacteria, and in a healthy gut there is a balance between these types of bacteria. Maintaining a healthy balance of bacteria is important for normal gut function, enabling the fermentation of fiber and carbohydrates, maintaining stool regularity, protecting against pathogenic bacteria, ensuring normal immune system development and facilitating nutrient metabolism. Factors that influence this balance of ‘good’ and ‘bad’ bacteria include age, medications, infection, the immune system and diet and possibly pre- and probiotic consumption. Because certain types of beneficial bacteria (eg. bifidobacteria) feed on prebiotic fibres, one way of increasing the number of good bacteria in the gut is by eating prebiotic carbohydrates. Microbial population in the gut might also be influenced by probiotic supplement consumption.

Monash Research into a high prebiotic diet

The Department of Gastroenterology at Monash University is researching the impact of a 'high fibre and high natural prebiotic diet'. This diet is designed to establish a healthy balance of gut bacteria, needed for optimal health. While the diet is essentially a high fibre diet, it emphasises the consumption of foods that are high in 'prebiotic' fibres.

What is a prebiotic?

A prebiotic is a type of fibre, thus while all prebiotics are fibre, not all fibre is prebiotic. To be classified as a prebiotic, the fibre must pass through the GI tract undigested; undergo fermentation by beneficial bacteria and selectively stimulate the growth and/or activity of certain strains of beneficial bacteria in the large intestine

What foods are naturally high in prebiotics?

Carbohydrates classified as having prebiotic effects include inulin, lactulose, fructooligosaccharides (fructans / FOS) and galactooligosaccharides (GOS). The following table outlines food sources of prebiotics:

Vegetables	Jerusalem artichokes, chicory, garlic, onion, leek, shallots, spring onion, asparagus, beetroot, broccoli, brussels sprouts, butternut pumpkin, savoy cabbage, fennel bulb, green peas, snow peas, sweetcorn
legumes	Chickpeas, lentils, red kidney beans, baked beans, soybeans
Fruit	Custard apples, nectarines, white peaches, persimmon, tamarillo, watermelon, rambutan, grapefruit, pomegranate
Bread / cereals / snacks	Barley, rye bread, rye crackers, wheat bread, pasta, gnocchi, couscous, wheat bran, oats, muesli-based fruit bars
Nuts and seeds	Cashews, pistachio
Other	Human breast milk

Legumes are particularly good sources of prebiotics. The following chart compares the prebiotic content of different legumes.

What are the health benefits of eating a diet high in prebiotics?

Because prebiotics are a relatively new discovery, evidence supporting their health benefit is only beginning to accumulate. Some health benefits attributed to prebiotic intake include modulation of the gut microbiota; improved mineral absorption; protection against colon cancer; improved blood glucose and insulin profiles; protection against intestinal infections and alterations in the progress of some inflammatory conditions.

For high prebiotic recipe ideas and a meal plan, check out the Monash University High Natural Prebiotic Diet webpage: http://www.med.monash.edu/cecs/gastro/prebiotic/

Lupins: Full of Goodness

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 individuals.

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!

References:

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 individual 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.

Legumes and Diet Quality

By Dr Alison Hill PhD, APD and Assoc Prof Alison Coates PhD, RNutr, University of South Australia

Pulses are part of the legume family, the most common varieties being dried peas, lentils, edible beans and chickpeas. Pulses have a unique nutrient composition: they are high in carbohydrate and protein and very low in total fat, which contributes to a low glycaemic index. They are rich in fibre and are a good source of vitamins and minerals, including, vitamin E, magnesium and iron. They also contain a complex mix of bioactives, such as oligosaccharides, lectins, enzyme inhibitors, phytates, and phenolic compounds that have, among other benefits, antioxidant properties. Observational studies have shown that frequent consumption of pulses (more than 4 times/week) is associated with a reduced risk of chronic diseases including 22% and 11% lower risk for coronary heart disease and cardiovascular disease, respectively compared to infrequent consumption (less than 1 time/week).¹

Due to their nutritional profile, pulses can be included within the Australian Dietary Guidelines in the vegetables and legumes/beans group (which are rich in fibre, vitamins and minerals), or in the lean meat and poultry, fish, eggs, tofu, nuts and seeds, legumes/beans group (which are rich in protein, and trace minerals)². When incorporated as a vegetable, 1 serve is ½ cup (75g) of cooked legumes while double the volume (150g) is needed for 1 serve as a meat alternative in order to provide sufficient protein. The inclusion of pulses in the diet therefore has the potential to improve diet quality.

Consuming a wide variety of nutrient-dense foods from within and across each food group may promote adherence to dietary patterns that have good diet quality3. The concept of diet quality allows for comparison of eating behaviours and linking of dietary patterns and health status. Typically, diet quality is assessed by comparing the intake of specific nutrients, or food groups, or a combination of both, against adequacy of nutrients or food-based dietary guidelines4. Diet quality scores have been developed that focus on legume consumption as a measure of adherence to a Mediterranean dietary pattern5 with legumes considered to be a beneficial component of the diet due to their nutrient profile. Better adherence to a Mediterranean dietary pattern containing legumes has been associated with greater longevity⁵. 

The relationship between pulse consumption and nutrient intakes and diet quality has been evaluated in 2 large observational studies, using data collected from the USA and Canada where pulse consumption is typically low (~8-13% of adults reported consuming pulses on any given day)^{6, 7}.  These studies demonstrated that compared to non-consumers, pulse consumers had higher intakes of protein, fibre, zinc, iron, folate and magnesium.  Such differences, along with lower intakes of total and saturated fat, were observed with as little as ½ cup/day of pulses⁶.

In an Australian context, this is important because pulse consumption is extremely low. The most recent survey of Australians reported that only 4.6% of adults had consumed pulses on the day prior⁸. Increasing intake of pulses by ½ cup/day may therefore be an achievable dietary change for much of the population. Future studies should evaluate whether the provision of pulses can improve nutrient intake and therefore diet quality in the Australian population.

GLNC recommends Australians enjoy legumes at least 2 – 3 times per week.

References:

1. Bazzano, L.A., et al., Legume consumption and risk of coronary heart disease in us men and women: Nhanes I epidemiologic follow-up study. Archives of Internal Medicine, 2001. 161(21): p. 2573-2578.
2. National Health and Medical Research Council, Australian Dietary Guidelines. 2013, National Health and Medical Research Council: Canberra.
3. Vandevijvere, S., et al., Overall and within-food group diversity are associated with dietary quality in Belgium. Public Health Nutr, 2010. 13(12): p. 1965-73.
4. Kant, A.K., Indexes of overall diet quality: a review. J Am Diet Assoc, 1996. 96(8): p. 785-91.
5. Trichopoulou, A., et al., Adherence to a Mediterranean Diet and Survival in a Greek Population. New England Journal of Medicine, 2003. 348(26): p. 2599-2608.
6. Mitchell, D.C., et al., Consumption of Dry Beans, Peas, and Lentils Could Improve Diet Quality in the US Population. J Am Diet Assoc, 2009. 109(5): p. 909-913.
7. Mudryj, A.N., et al., Pulse consumption in Canadian adults influences nutrient intakes. British Journal of Nutrition, 2012. 108(SupplementS1): p. S27-S36.
8. Australian Bureau of Statistics, Australian health survey: nutrition first results - foods and nutrients, 2011-12. 2014, ABS: Canberra.