Mediterranean diet and metabolic syndrome

The olive tree may be the secret to the Greeks' longevity, with Greece displaying longer life expectancy and lower rates of heart disease than countries like Australia and America.

A study of seven countries found that Greek men living in Crete and aged over 40 had half the chance of dying and less than one tenth the chance of dying from heart disease before the age of 60, compared to other countries in the study.¹

According to Practising Dietitian Dr Catherine Itsiopoulos of the University of Melbourne, the explanation is that the Greeks and other Mediterranean cultures use olive oil rather than animal fats in their foods.

"Following the Mediterranean diet, it is possible to prevent the metabolic syndrome and reduce the risk for type 2 diabetes and cardiovascular disease."

Meals high in saturated fat cause immediate increases in triglycerides, oxidative stress and inflammation thus worsening endothelial dysfunction.

Diets high in monounsaturated fat (olive oil) on the other hand, are associated with reduced abdominal obesity compared with high CHO diets, and greater weight loss compared with high saturated fat diets (matched for energy and total fat).

Thus, a significant improvement in cardiovascular health can be achieved by replacing animal fats with olive oil in cooking and salads, grilling and baking rather than frying, and using canola or olive-based margarine instead of butter.

The Mediterranean diet is also characterised by a high intake vegetables (particularly leafy greens and tomatoes), legumes, fruits, nuts, unrefined cereals and wine with meals.

Dr Itsiopoulos says the Mediterranean diet could hold the key to reversing the alarming trend of obesity and heart disease in Australia.

"We have 9 million people in Australia who are overweight or obese. Our obesity rates have surpassed the rest of the Western world."

One in three Australians 25 years and over are believed to have metabolic syndrome, a cluster of cardio-metabolic risk factors that increase the risk of cardiovascular disease and type 2 diabetes.²

The International Diabetes Federation (IDF) released the following global definition of metabolic syndrome in 2005:³

Central obesity
- Waist circumference for Europids, Sub Saharan Africans, Eastern Mediterranean and Middle East (Arab) language populations: males ≥ 94cm, females ≥ 80cm
- Waist circumference for South Asians, Chinese, Japanese, ethnic South and Central American language populations: males ≥ 90cm, females ≥ 80cm
Plus any two of the following:
1. Raised triglycerides ≥ 1.7 mmol/L or specific treatment for this abnormality
2. Reduced HDL-C <1.03 mmol/L (M) < 1.29 mmol/L (F) or specific treatment for this abnormality
3. Hypertension: ≥ 130/85 mmHg or medication
Fasting plasma glucose ≥ 5.6 mmol/L or previously diagnosed type 2 diabetes

There are many dietary strategies that can be used in the management of metabolic syndrome, and not surprisingly, most of them are displayed in the Mediterranean diet:

An increased intake of low-fat cheese and yoghurt; as prospective and cohort studies have shown that 3–5 serves dairy foods per day are protective against metabolic syndrome, whilst cheese does not increase cholesterol in RCTs.^4-7
An increase in intake of long-chain omega-3 fatty acids DHA and EPA from seafood, which is associated with reduced TGs and FFAs, reduced ectopic fat depots in liver and reduced IR.⁸
A decreased intake of highly processed, low fibre, high GI carbohydrate foods as they are associated with increased post-prandial glucose and triglycerides and increased risk of CVD and diabetes. (Recommend wholegrain carbohydrates instead).^9,10
An increased intake of fresh fruit, with peel. Discourage intake of high-fructose corn syrup in soft drinks, cordials, sweetened processed foods, as these cause a minimal rise in BGLs and insulin, and its uptake directly into liver increases TGs, VLDL and associated with central obesity and insulin resistance.¹¹

"There is substantial evidence in the support of the Mediterranean diet in the management and prevention of metabolic syndrome," says Dr Itsiopoulos.

Overall, a Mediterranean diet is recommended, as it is associated with improvements in metabolic syndrome compared with other prudent diets. It is associated with a 70% reduction in secondary CVD events in post AMI subjects compared with AHA diet, and adherence to a Mediterranean diet is associated with longevity.^1,12,13

Recommend:

Olive oil as main added fat
Vegetables (especially leafy greens and tomatoes) every day
Legumes twice per week
Less meat and more fish
No day without fruit
Yoghurt every day and cheese in moderation
Wholegrain cereals in moderate quantity
Wine in moderation with meals
Sweets / sweet drinks for special occasions only

If the statistics are anything to go by, a Mediterranean diet could add years to a patient's life!

Click here to watch clinical dietitian Dr Catherine Itsiopoulos discuss the metabolic syndrome.

References:

de Lorgeril M, et al. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: Final report of the Lyon Diet Heart Study. Circulation. 1999; 99: 779-85.
Dunstan, et al. The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) – methods and response rates. Diabetes Res Clin Pract 2002; 57: 119-29.
Alberti K, et al. The metabolic syndrome – a new worldwide definition. Lancet. 2005; 366: 1059-62.
Pereira M, et al. Dairy consumption, obesity, and the insulin resistance syndrome in young adults: The CARDIA study. JAMA. 2002; 287(16): 2081-9.
Liu S, et al. Dietary calcium, vitamin D, and the prevalences of metabolic syndrome in middle-aged and older U.S. women. Diabetes Care. 2005; 28(12): 2926-32.
Nestel PJ, et al. Dairy fat in cheese raises LDL cholesterol less than that in butter in mildly hypercholesterolaemic subjects. Eur J Clin Nutr. 2005; 59(9): 1059-63.
Biong AS, et al. A comparison of the effects of cheese and butter on serum lipids, haemostatic variables and homocysteine. Br J Nutr. 2004; 92(5): 791-7.
Carpentier YA, et al. N-3 fatty acids and the metabolic syndrome. Am J Clin Nutr. 2006; 83: 1499S-1504S.
O'Keefe, et al. Dietary strategies for improving post-prandial glucose, lipids, inflammation, and cardiovascular health. J Am Coll Cardiol. 2008; 51(3): 249-55.
Beulens J, et al. High dietary glycemic load and glycemic index increase risk of cardiovascular disease among middle-aged women. J Am Coll Cardiol. 2007; 50: 14-21.
Bray G, et al. Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. AJCN. 2004; 79: 537-43.
Esposito K, et al. Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome: A randomized trial. JAMA. 2004; 292: 1440-6.
Trichopoulou A, et al. Modified Mediterranean diet and survival: EPIC-elderly prospective cohort study. BMJ. 2005; 330, 991.