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Going nuts a must for healthy hearts

by Thel Krollig

Mixed nutsNuts have been given the thumbs up by UniSA nutritional researchers as an important part of a well-balanced diet and one that can reduce the risk of developing heart disease.

A summary of scientific evidence, presented by Professor Peter Howe and Dr Alison Coates from UniSA’s Nutritional Physiology Research Centre supports the nut industry’s description of their product as "nature’s vitamin pills".

Edible nuts and metabolic health, published recently in the international journal Current Opinion in Lipidology, gives the link between nuts and healthy hearts a strong endorsement.

Dr Coates and Prof Howe say nuts are ready-to-eat snack foods that are satisfying, have healthy lipid profiles and are excellent sources of protein.

Researchers found that other common foods in our diet such as grapes, dark chocolate, fruits, vegetables and garlic are important sources of bioactive nutrients.

"While collectively these foods offer an alternative approach for the prevention and management of cardiovascular disease, we examined the role of nuts alone in providing health benefits," Prof Howe said.

UniSA researchers looked at nuts in terms of their impact in six key areas - bioactive nutrients, impact on body weight and obesity, influence on appetite and energy balance, beneficial effects on blood lipids, beneficial effects on endothelial function, and insulin sensitising effect of nuts.

"While fat accounts for 50 to 70 per cent of the macronutrient contents of nuts, making them an energy dense food, the nut is also a nutrient dense food in which the quality of the fat, which is predominantly monounsaturated fatty acid, is of greater significance than its energy content," Prof Howe said.

"Nuts are also a rich source of bioactive nutrients that have the potential to deliver metabolic and cardiovascular health benefits."

And while the high calorie content of nuts has caused concern that their consumption would promote weight gain, the data revealed that Body Mass Index values were lower in nut consumers than in those who do not eat nuts.

"While there is no evidence to support nuts as contributing to weight reduction, including nuts in an energy restricted diet can help promote weight loss or at least limit weight gain," Dr Coates said.

The research also concluded that appetite suppression may result from satiating effects of the high fibre, protein and energy contents of nuts.

There is an extensive body of literature describing the beneficial effects of nuts on lipid profiles, with the most recent reviews concluding that a 50 to 100g intake of nuts five or more times a week will help decrease the total of low density lipoprotein or "bad" cholesterol and protect against cardiovascular disease.

"Maintaining the functional capacity of the endothelial cells lining blood vessels is vital to vascular health and improvements in endothelial vasodilator function have been reported with high nut consumption," Prof Howe said.

Further, evidence to support a beneficial effect of nuts on insulin sensitivity came from a major Nurses Health study, reporting an inverse association between nut consumption and the risk of developing Type 2 diabetes.

"We can conclude from this review that nuts have equally important benefits for metabolic health, in terms of weight management and prevention of insulin resistance, high blood fat and poor blood vessel function," Dr Coates said.

"However, further research is needed to establish the intakes of different varieties of nuts, alone or in combination with other foods, to deliver optimal cardiovascular and metabolic benefits."