The Mediterranean Diet - Benefits Beyond Heart Health

By Felicity Curtain, Accredited Practising Dietitian

A Mediterranean eating pattern has long been heralded as the diet of all diets: seemingly unrestrictive, uncomplicated in rules and with strong credentials for heart health benefits. However, recent research suggests there may be more to the story than just heart health. The Mediterranean diet first sparked interest in the 1960s, when it was discovered that people in countries bordering the Mediterranean Sea experienced significantly lower rates of chronic disease than those in western countries. While most research in the past has focussed heart health benefits, studies have recently started connecting the diet to reduced risk of Type 2 diabetes, cancer, and cognitive conditions.

The Diet
Over twenty countries border the Mediterranean Sea, and while types and amounts of foods eaten vary between nations, all are characterised by similar principles. This includes plenty of fruit and vegetables, olive oil, legumes, nuts and whole grains; moderate consumption of fish, and low-moderate amounts of dairy foods and red meat. Very few processed foods are consumed, and red wine is consumed in moderation with meals (1). While studies do not explicitly outline the types of whole grains consumed, varieties common to the Mediterranean include barley, buckwheat, bulgur, faro, oats, polenta, rice, bread, couscous, and pasta. The past century has included white pasta, though traditionally bread was stone-ground sourdough, made from whole wheat and barley (2).

The Health Effects
If you believe the media coverage of the diet, the benefits of a Mediterranean appear boundless. In reality, high quality evidence exists to indicate the eating pattern is protective against cardiovascular disease (CVD) and Type 2 diabetes, and mounting evidence points to a positive association with cancer and neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease (3,4,5).

The most recent research indicates that for those already exhibiting CVD risk factors, following a Mediterranean diet can halve the risk of diabetes development and reduce the risk of mortality from cardiovascular events by 30 percent (6). Observational evidence and limited experimental trials demonstrate that those adhering to the diet exhibit improved blood lipid profiles, a reduction in blood pressure, and insulin resistance, all risk factors for CVD (7,8). In fact, the cardiovascular benefits of the Mediterranean diet have been compared to pharmacological interventions, such as statins, aspirin, physical activity, and even anti-hypertensive drugs (9). In healthy populations, observational evidence suggests a 10 percent decrease in the risk of mortality and/or incidence of CVD (10).

Interestingly, few studies of the Mediterranean diet are designed to induce weight loss, but many participants do lose weight, a risk factor for chronic disease itself. It has been suggested that that may be due to the high ratio of plant to animal foods, and limited refined and processed foods, making the diet high in fibre and filling, without providing excess energy.

In recent years, a small pool of trials has shown preliminary evidence that the Mediterranean diet may slow the onset and/or progression of age-related cognitive decline, and promote healthy cognitive ageing. One such study found that greater adherence to a Mediterranean diet corresponded with lower decline in cognitive function over a five-year period. In younger adults, there is growing interest in the effects of the diet on mood and affective disorders, based on population data showing low depression rates in Mediterranean countries. Limited high-level evidence exists on the subject, however a number of Australian randomised control trials are currently being carried out to determine the link between the diet and mood disorders (11).

Considerable research has sought to understand the mechanisms behind the Mediterranean diet’s apparent link to health, with no single food or nutrient appearing to contribute in isolation. While the mechanisms are not fully understood, there is a general consensus among experts that it is based on the combination of protective nutrients and foods. The high ratio of plant to animal foods may be a contributing factor, particularly as foods like olive oil, herbs and spices, fruit, vegetables, whole grains and legumes are rich in phytochemicals, with antioxidant, anti-inflammatory effects.

These factors are also thought to relate to the emerging link between a Mediterranean diet and positive cognitive health. The combination of foods and nutrients are thought to protect against cognitive decline through reductions in oxidative stress, inflammation, and lowering insulin resistance. The diet may also help to increase cerebral blood flow, a factor that is inversely affected by a typical Western diet (12,13).

However, it should not be forgotten that the good health of Mediterranean populations may also relate to lifestyle and cultural elements central to their traditions. Cooking, socialising, regular physical activity and rest are all important factors to consider in a balanced lifestyle.

Incorporating Mediterranean Eating Habits into Australian Diets
Interestingly the macronutrient distribution of the Mediterranean diet is not that dissimilar to the average Australian diet (Table 1). The Mediterranean diet is slightly lower in protein and carbohydrate and higher in fats, largely from the free consumption of olive oil, nuts, and seeds. The Mediterranean diet is significantly higher in fibre than the average Australian diet (33g/day compared to 22- 23g/day), a reflection of the higher intake of fibre rich foods including vegetables, legumes, whole grains and nuts.

Table 1. Average macronutrient contribution to energy and total fibre intake of Australians average intakes compared to estimated Mediterranean diet macronutrient distribution ranges and fibre intakes.

 

	Mediterranean Diet	Australian Average(14)
Protein	10-15%	16%
Carbohydrate	43%	45%
Fat	30-40%	31%
Fibre	33g/day	22g (F) 23g (M)

Comparing the diets from in terms of foods, a noteworthy distinction between the Mediterranean Diet Pyramid and the Australian Dietary Guidelines is the former does not detail serve sizes, instead emphasizing overall food quality according to dietary patterns.

Table 2. The Mediterranean Diet Pyramid compared to the Australian Dietary Guidelines

Food Group	Mediterranean Diet Pyramid	Australian Dietary Guidelines (men and women 19-50).
Vegetables	2 or more serves per meal (6+ per day)	5 serves per day
Fruit	1-2 serves per meal (3+ per day)	2 serves per day
Breads & Cereals	1-2 serves per meal (3+ per day)	6 serves per day
Dairy	2 serves per day	2 ½ - 3 serves per day
Meat & Alternatives	2 serves of red/white meat per week, 2 or more serves of fish/seafood, and legumes per week, 2-4 serves of eggs per week, 1 or fewer serves of processed meat per week.	2 ½ - 3 serves per day (inclusive of red meat, poultry, fish, legumes, nuts, seeds).
Oils	Olive oil in unspecified amounts daily	4 serves per day
Olives, nuts, and seeds	1-2 serves daily	-
Discretionary Foods	2 or fewer serves daily	0-3 serves per day

In reality we know that Australian diets do not reflect the guidelines, with an average of one third of total daily energy stemming from discretionary foods, and less than seven percent of the population meeting the recommendations for vegetable intake (14).

A simple way for Australian to adjust their diets and reap the benefits of the Mediterranean diet is to increase the amount of vegetables, nuts, whole grains and legumes eaten each day. This can be coupled with including small amounts of red meat a few times a week and increasing consumption of fish, using olive oil and as the main fat source, and using fresh herbs and spices to add flavour to meals in place of salt.

References
1. Sofi F, Abbate R, Gensini GF, Casini A. Accruing evidence on benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis. Am J Clin Nutr. 2010;92:1189-96
2. D'Alessandro A, De Pergola G. Mediterranean Diet Pyramid: A Proposal for Italian People. Nutrients. 2014;6(10):4302-4316.
3. Itsiopoulos C. The Mediterranean Diet. Melbourne: Pan Macmillan Australia; 2013.
4. Sofi F, Abbate R, Gensini GF, Casini A. Accruing evidence on benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis. Am J Clin Nutr. 2010;92:1189-96
5. Trichopolou A, et al. Definitions and potential health benefits of the Mediterranean diet: views from experts around the world. BMC Medicine. 2014; 12:1121-16.
6. Estruch R, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet. N Engl J Med. 2013; DOI: 10.1056/NEJMoa1200303
7. Kastorini C, Milionis H, Esposito K, Giugliano D, Goudevenos J, Panagiotakos D. The Effect of Mediterranean Diet on Metabolic Syndrome and its Components. Journal of the American College of Cardiology. 2011;57(11):1299-1313.
8. Grosso G, Mistretta A, Frigiola A, Gruttadauria S, Biondi A, Basile F et al. Mediterranean Diet and Cardiovascular Risk Factors: A Systematic Review. Critical Reviews in Food Science and Nutrition. 2013;54(5):593-610.
9. Trichopolou A, et al. Definitions and potential health benefits of the Mediterranean diet: views from experts around the world. BMC Medicine. 2014; 12:1121-16.
10. Sofi F, Abbate R, Gensini GF, Casini A. Accruing evidence on benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis. Am J Clin Nutr. 2010;92:1189-96
11. Preedy V, Watson R. The Mediterranean diet. USA: Elsevier; 2015.
12. Knight A, Bryan J, Wilson C, Hodgson J, Murphy K. A randomised controlled intervention trial evaluating the efficacy of a Mediterranean dietary pattern on cognitive function and psychological wellbeing in healthy older adults: the MedLey study. BMC Geriatric. 2015;15:55
13. Keast R, Parkinson L. 2016. Available from: http://eds.a.ebscohost.com.ezproxy-b.deakin.edu.au/eds/pdfviewer/pdfviewer?sid=e44b952b-b40c-49f5-8c2d-2a746edcb669@sessionmgr4001&vid=5&hid=4103
14. Australian Bureau of Statistics. Australian Health Survey: Nutrition First Results. 2015. Available from: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/4364.0.55.007~2011-12~Main%20Features~Cereals%20and%20cereal%20products~720

Department of Health - Healthy Weight Guide

The Department of Health has released the Healthy Weight Guide (the Guide). The Guide consists of a website as well as supporting resources that have been developed to help Australians achieve and maintain a healthy weight. 

The Healthy Weight Guide website contains information and tools that will guide users to:

1. Set goals and plan healthy meals and physical activity
2. Monitor what they do and manage challenges
3. Find information and support that will guide them along the way.

The primary audience for the Guide is the Australian general public. However, organisations and health professionals may also find the Guide useful as a resource for gaining background information on healthy weight issues or for suggesting to consumers as a practical tool to assist them in achieving and maintaining a healthy weight.

The Guide includes links to a variety of relevant sources and a page is included for each state and territory that provides links to state and territory specific programmes and resources.

Latest Look at Legumes

Legumes are trending. They’re featuring on restaurant menus, in glossy magazines and even in lunch-time salad bars. Research is mirroring the interest with new research emerging to strengthen the evidence for a range of health benefits of legumes.

A review published in Asia Pacific Journal of Clinical Nutrition in March by Australian researchers Antigone Kouris-Blazos and Regina Belski outlines the latest evidence for the nutrition and health benefits of legumes. This extensive review considers the evidence for the effect of legumes, and in particular Australian Sweet Lupin, on longevity, diabetes, cardiovascular disease, cancer and weight management. In addition, the review considers the content of both nutrients and anti-nutrients in legumes as well as comparing current intakes with recommendations.

While most people would think of heart health as the first benefit of legumes, the authors in fact suggest the strongest evidence is for links between eating legumes and reduced risk of colorectal cancer. The World Cancer Research Report in 2006 concluded that there was limited evidence on legume consumption and reduced risk of cancer. However, it appears the evidence for legumes maybe strengthening. Three meta-analyses in the last 7 years have found eating legumes is associated with a reduced risk of bowel cancer. The bulk of this research has been conducted on the effect of soy intake.

In addition to colorectal cancer, this review outlines the evidence of benefits of eating legumes regularly for longevity, as well as reduced risk of and management of diabetes, cardiovascular disease and obesity. The authors suggest that one of the key factors for the benefits of legumes may be via favourable effects on the gut microbiome.

Australian Sweet Lupin is a crop grown predominantly in Western Australia but is not well known by many Australians. The review puts of focus on this little-known legume and suggests these are unique with one of the highest combined amounts of digestible plant protein (38%) and dietary fibre (30%). The authors note that low levels of anti-nutritional factors means they do not need to be soaked, or even cooked so can be eaten raw. Initial evidence suggests sweet lupins may lower blood pressure, improve blood lipids and insulin sensitivity and favourably alter the gut microbiome.

Kouris A, Belski R. Health benefits of legumes and pulses with a focus on Australian sweet lupins. Asia Pac J Clin Nutr. 2016;25(1):1-17.

Fibre - The Hallmark of a Healthy Diet

The most recent National Nutrition Survey showed that grain foods are the leading source of fibre in the diets of young Australian women delivering a whopping 42.4% ⁽¹⁾. However, despite this important link between grain foods and fibre, many young women fall short of their core grain intake recommendation⁽²⁾. But why is this? Despite being the hallmark of healthy eating, dietary fibre rarely captivates the attention of young women, however the results of a new study⁽³⁾ have bolstered the case for fibre to be recognised as a, if not the, leading health promoting component of food. This has raised concern that young women may be missing the benefits of a high fibre diet, of which high fibre grain and whole grain foods play an important role. Here we have summarised the results of this recent study in light of the dietary fibre and core grain intakes of young Australian women.

PhD candidate, young woman and lead author of the new review on dietary fibre⁽³⁾ Stacey Fuller said, “The evidence has shown time and time again that people who eat higher fibre diets experience greater digestive wellbeing and reduced risk of specific cancers, heart disease, diabetes and obesity – some of the biggest causes of death and disability in Australia. Despite the overwhelming body of evidence emphasising the importance of a high fibre diet for wellbeing, Australians are falling short of fibre recommendations, particularly young women aged 19-30 years, who on average consume around 20g of dietary fibre per day (25g recommendation)⁽¹⁾.

Co-author, Associate Professor Eleanor Beck of the University of Wollongong stated, “While people generally understand that fibre is important for digestive health, there is a lack of understanding of the additional and wide ranging benefits of fibres for disease risk reduction and as a result, there is a lack of appreciation of the importance of eating a variety of high fibre foods as part of a balanced diet.”

What many people don’t realise is that fibre is not a single nutrient but rather a range of complex components found in a variety of foods including grains, legumes, fruits, vegetables, nuts and seeds. Pectin, which is found in a range of plant-based foods, including legumes, fruit, vegetables, nuts and seeds, has been shown to reduce cholesterol reabsorption and improve bowel health. Other types of fibre such as β-Glucan, a type of cereal fibre, is found more exclusively in grain foods such as barley and oats. Cereal fibre has been shown to offer the greatest protection against risk of early death, compared with other types of fibre⁽⁵⁾. Just 10g of cereal fibre per day can reduce future risk of heart disease by 10%(4) and type 2 diabetes by 35%⁽⁶⁾.

Whilst core grain foods are the major source of fibre in all Australian’s diets, the 2014 GLNC Consumption and Attitudinal Survey showed that people are much less likely to identify grains (and legumes) as sources of dietary fibre compared to fruit and vegetables⁽²⁾. On top of this, many young women believe that grain foods, including those that are high in fibre (e.g. wholemeal pasta, whole grain bread), are not an important part of a healthy diet⁽²⁾. What they don’t understand is that by limiting their intake of core grains, they not only compromising their fibre intake but also their consumption of a wide range of other essential nutrients and protective components found in fibre rich grain foods.

This recent review highlights the need for a greater understanding that when it comes to fibre, variety is essential, and all Australians should be encouraged to eat a variety of fibre-rich plant foods including grains, legumes, fruits, vegetables, nuts and seeds as part of a balanced diet. To help meet dietary fibre recommendations and achieve fibre intakes associated with wellbeing in the short term and reduced risk of chronic disease in the long term, young women should aim to enjoy core grains foods three to four times each day, choosing at least half as whole grain and/or high fibre grain foods, within a balanced diet rich in other source of dietary fibre. This could be as easy as having a bowl of porridge with fruit for breakfast, a whole grain salad sandwich for lunch and a vegetable stir-fry with brown rice or barley for dinner.

For a range of fibre rich recipes, cooking tips and snack ideas with grains and legumes visit the GLNC website.

References

1.         ABS. National Health Survey: First Results, 2014-15. Australian Bureau of Statistics, 2014-15.

2.         GLNC. 2014 Australian Grains and Legumes Consumption and Attitudinal Report. Unpublished: 2014.

3.         Fuller S, Beck E, Salman H, Tapsell L. New Horizons for the Study of Dietary Fiber and Health: A Review. Plant foods for human nutrition. 2016.

4.         Pereira MA, O'Reilly E, Augustsson K, Fraser GE, Goldbourt U, Heitmann BL, et al. Dietary fiber and risk of coronary heart disease: a pooled analysis of cohort studies. Arch Intern Med. 2004;164(4):370-6.

5.         Kim Y, Je Y. Dietary Fiber Intake and Total Mortality: A Meta-Analysis of Prospective Cohort Studies. American journal of epidemiology. 2014;180(6):565-73.

6.         Yao B, Fang H, Xu W, Yan Y, Xu H, Liu Y, et al. Dietary fiber intake and risk of type 2 diabetes: a dose-response analysis of prospective studies. European journal of epidemiology. 2014;29(2):79-88.