Nuts and health

Nuts are a healthy plant food, packed full of beneficial nutrients for good health - they are high in healthy unsaturated fats, protein and fibre as well as containing a broad range of vitamins, minerals and phytochemicals.

Belinda Neville, Dietitian and Nutrition Program Manager at Nuts for Life answers some of your common questions about nuts.

What are tree nuts?

Tree nuts, as the name suggests grow on trees. They include: almonds, brazil nuts, cashews, chestnuts, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts.

Whilst peanuts are often referred to as a nut, they are in fact legumes. However, they have a similar nutrient composition to that of tree nuts.

What nutrients do nuts provide?

Like other plant foods, nuts provide a range of beneficial nutrients, essential for good health. 

They are rich sources of healthy monounsaturated and polyunsaturated fats; contain moderate amounts of protein; and contribute fibre.

Nuts also provide a wide range of essential nutrients, including several B group vitamins (including folate), vitamin E, calcium, iron, zinc, potassium and magnesium; antioxidant minerals (selenium, manganese and copper), plus other phytochemicals such as antioxidant compounds (flavonoids and resveratrol) and plant sterols.

Nuts are also naturally low in sodium, contain potassium and most contain some carbohydrate in the form of natural sugars. Chestnuts are different in that they are rich in low glycaemic index carbohydrates, and are low in fat making their composition more like a grain than a tree nut.

Each nut variety contains its own unique combination of nutrients and is generally rich in a few nutrients such as:

  • Almonds: protein, calcium and vitamin E
  • Brazil nuts: fibre and selenium - just two brazil nuts a day provides 100% RDI for selenium for an adult
  • Cashews: non-haem (plant based) iron and a low GI rating
  • Chestnuts: low GI, fibre and vitamin C
  • Hazelnuts: fibre, potassium, folate, vitamin E
  • Macadamias: highest in monounsaturated fats, thiamin and manganese
  • Pecans: fibre and antioxidants
  • Pine nuts: vitamin E and the amino acid arginine
  • Pistachios: protein, potassium, plant sterols and the antioxidant resveratrol
  • Walnuts: alpha linoleic acid (plant omega 3) and antioxidants.
Is there a nutritional difference between raw and roasted nuts?

There is little difference in the nutrient content of raw and roasted nuts. Nuts can be oil or dry roasted, but nuts are so dense, that they are unable to absorb much oil i.e. they only absorb approximately 2-5% of the oil they are cooked in.

Roasting reduces the water content of nuts, concentrating the nutrients, but also reduces the concentration of several B group vitamins as they are not heat stable.

Whilst it’s possible to buy unsalted, dry roasted nuts, many oil roasted nut varieties are salted and therefore have a higher sodium content than raw nuts. If you like the taste of roasted nuts, but want to reduce your salt intake, choose unsalted roasted nuts and leave the salted ones for special occasions only.

Are nuts good for heart health?

Yes. Studies show that enjoying about 30g (a handful) of nuts per day may reduce the risk of developing heart disease by 30-50% and reduce the risk of death from heart disease by around 20%.  Eating an average of 67g (two handfuls) of nuts a day can also help improve cholesterol.

Nuts contain a variety of nutrients and other bioactive substances that work together to achieve this heart protective effect. These include:

  • Health-promoting monounsaturated and polyunsaturated fats that help regulate blood cholesterol
  • Fibre and plant sterols that help reduce cholesterol re-absorption from the gut
  • Arginine (an amino acid which is converted to nitric oxide in the body) which helps keep blood vessels elastic, thereby reducing the risk of atherosclerosis (hardening of the arteries)
  • Antioxidant vitamins and minerals, e.g. vitamin E, copper, manganese, selenium and zinc, and other antioxidant compounds such as flavonoids and resveratrol that reduce oxidation and inflammation
  • Naturally low sodium and high potassium levels which assist in maintaining healthy blood pressure.
Do nuts affect my risk of developing type 2 diabetes?

Nuts may reduce the risk of developing type 2 diabetes.

Studies have shown that eating a 30g handful of nuts at least four times a week reduces the risk of developing type 2 diabetes by 13-27%, compared to eating fewer or no nuts.  This effect is attributed at least partly to the high levels of monounsaturated and polyunsaturated fats found in nuts, which (in addition to their positive effects on blood cholesterol) are believed to enhance insulin sensitivity.

Nuts can also benefit people with type 2 diabetes, as they help reduce the overall glycaemic index of the diet. When added to meals rich in carbohydrate, nuts slow the passage of the meal through the gut and reduce blood glucose levels following the meal. The phytochemicals found in nut skins may slow carbohydrate digestion.

Nuts can also help reduce the risk of developing Metabolic Syndrome – a cluster of metabolic measures that if left untreated, can lead to type 2 diabetes, heart disease and hypertension (high blood pressure).

Can nuts help to control weight?

Yes. A small handful of nuts (30–50g) each day is not associated with a weight gain, and may in fact help reduce the risk of obesity. There are several mechanisms by which nuts help manage weight:

  • The healthy fats, protein and fibre in nuts can help you feel fuller, which helps to control appetite and satisfy hunger
  • Some of the fat is trapped in the fibrous structure of the nut, so it passes through the body rather than being absorbed
  • Nuts can increase energy expenditure by approximately 10%.

The bottom line - nuts can be part of a healthy diet to maintain or even lose weight, as nut eaters tend to have a lower BMI compared to those who don’t eat nuts.

Can I eat nuts in a Mediterranean diet?

Absolutely. Including a handful of nuts (30g) every day in a Mediterranean diet has more health benefits than a reduced fat diet. One study found the following:

  • Reduced cardiovascular events such as myocardial infarction, stroke, and death from cardiovascular causes
  • A lifetime habit of eating a handful of nuts (30g) more than three times a week resulted in a 39% reduction in total mortality in an older Mediterranean population at high risk of cardiovascular disease
  • BMI and waist circumference decreased by 0.78kg/m2 and 2.1cm respectively, for each additional serving of nuts eaten
  • 50% reduction in diabetes incidence, compared to following the low-fat diet over four years
  • 26% reduction in metabolic syndrome comparing those eating three or more serves of nuts per week with one or fewer serves per week.

For more information, download the PREDIMED summary paper at http://www.nutsforlife.com.au/resources/literature-reviews-summaries/

What about nut allergies?

Nut allergies are a major concern for a small proportion of the population, and as there is no cure, total avoidance of the allergen is the only management. People can be allergic to:

  • one or more of the tree nuts
  • peanuts only
  • both tree nuts and peanuts

For more information on managing tree nut allergy, download this Allergy and Anaphylaxis Australia reviewed fact sheet http://www.nutsforlife.com.au/wp-content/uploads/2014/12/Nuts-and-allergy-facts-LR.pdf or visit http://www.allergyfacts.com.au

What other health benefits do nuts provide?

Regular nut consumption has also been linked to a host of other health benefits including:

  • Reducing the risk of gall stones
  • Reducing age-related macular degeneration (which can lead to blindness)
  • Maintaining bone health
  • Slowing brain aging
  • Reducing cancer risk
  • Living longer.

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How much nuts should you eat?

The 2013 Australian Dietary Guidelines state that a serve of nuts is 30g.  Much research has also confirmed that at least 30g of nuts a day is beneficial to health.

A healthy daily intake of 30g of nuts is equivalent to:

  • a small handful
  • 20 almonds
  • 4 chestnuts
  • 20 hazelnuts
  • 15 macadamias
  • 15 pecans
  • 2 tablespoons of pine nuts
  • 30 pistachio kernels
  • 10 walnut halves (i.e. 5 whole walnuts)

Acknowledgements

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Belinda Neville is a Dietitian and is the Nutrition Program Manager at Nuts for Life, a health education initiative of the Australia Tree Nut Industry and Horticulture Innovation Australia.

For more information on including nuts to your diet, visit www.nutsforlife.com.au or follow us on social media.

Updated 2018.

 

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