Guide to nuts
HFG senior nutritionist Rose Carr looks at the nutritional value of eating nuts — a sure way to include healthy fat in our diet.
Common tree nuts include Brazil nuts, almonds, walnuts, hazelnuts, macadamias, pistachios, pine nuts, cashews and pecans. Peanuts are actually ground nuts or legumes but as they have a similar nutrient profile to tree nuts and are used in the same way, they are considered as nuts. Chestnuts are also tree nuts but they have a different nutrient profile from common nuts.
Whole raw nuts have been described as nature’s health capsules as they’re chock-full of nutritional goodness. Nuts contain healthy monounsaturated and polyunsaturated fats, some with omega-3, along with good amounts of protein, fibre, folate, vitamin E, calcium, magnesium and potassium as well as plant sterols.
Nuts range from 46 per cent fat in cashews and pistachios to 76 per cent in macadamia nuts. Walnuts are very high in ALA — the natural plant omega-3 fat — while other nuts contain little, if any.
A 30g serve of nuts provides around 5-8g protein, although macadamia and Brazil nuts are lower at 3g and 3.5g respectively. Peanuts are particularly high in fibre with 30g providing 2.4g fibre, closely followed by almonds and hazelnuts with 2.2g fibre in a 30g serve. Peanuts are also highest in folate with a 30g serve providing 72mcg — that’s 18 per cent of the recommended dietary intake (RDI). Hazelnuts have around half that amount of folate.
Almonds are the star for vitamin E, providing over 70 per cent of the RDI in a 30g serve. Almonds are also higher in calcium than other nuts, with 75mg in a 30g serve, around eight per cent of the 1000mg RDI for most people. Brazil nuts and hazelnuts contribute around 55mg in the same sized serve.
Most nuts are also a good source of magnesium and Brazil nuts are particularly high in this mineral. A 30g serve of Brazil nuts provides 29 per cent (for men) to 38 per cent (for women) of the RDI for magnesium, with cashews and almonds also high at 18 to 23 per cent. Pistachios are especially high in potassium with around seven per cent of the suggested daily target in a 30g serve.
While most nuts provide little selenium, Brazil nuts are a rich source of this antioxidant mineral many of us don’t get enough of. Just two to three Brazil nuts each day provides 100 per cent of the RDI.
Many nuts also contain useful amounts of natural plant sterols which interfere with cholesterol absorption, which plays a role in lowering blood cholesterol. Peanuts and pistachios are particularly high in plant sterols.
With their high fat (or oil) content, nuts can go rancid if not treated with care. As with all oils, heat, air and light are the enemy, so store nuts in a cool, dark place in an airtight container to help maintain their freshness. A darkened container in the fridge is ideal.
Nuts and children
In the US it’s estimated that 0.2 per cent of the population is allergic to tree nuts and around nine per cent of children with a tree nut allergy will outgrow it.
It used to be recommended that the introduction of common food allergens such as nuts be delayed until 12 months of age to reduce the risk of allergies, but this is no longer the advice. There is even some evidence that delaying the introduction of nuts may increase the likelihood of an allergic response, although pending results from large trials may or may not confirm that.
Whole nuts should not be given to children until they reach five years of age as there is a risk they can inhale or choke on a nut. Instead use smooth nut pastes or ground nuts added to other foods.
Once children are five, a small handful of nuts each day is a great habit to get into. When giving children whole nuts (or any other food which could be a choking risk), make sure they sit down to eat and supervise them closely. Encourage them to eat small amounts at a time and to chew their food well.
Five reasons to eat nuts
1. Nuts taste great
Try raw whole nuts, freshly dry-roasted nuts or even nut butters. Get the most from nuts’ healthy nutrients by eating them fresh and not adding salt.
2. Nuts are satisfying
It may be the fibre, it may be the chewing required, but whatever it is, nuts tend to be more satisfying than the average muffin. In studies where nuts are added to people’s diets, the inclusion of nuts tends to reduce consumption of other foods.
3. Nuts are good for our hearts
Regularly eating nuts seems to play a role in the prevention of cardiovascular disease, coronary heart disease, myocardial infarction and even sudden death. Clinical studies suggest this is mainly because the nuts reduce total cholesterol, LDL-cholesterol and apolipoprotein B concentrations. The cholesterol-lowering effect of nuts seems to be more pronounced in people with high cholesterol, those who are overweight and those who are insulin-sensitive. The Heart Foundation recommends people with high cholesterol eat 30g nuts each day to reduce their cholesterol.
4. Contrary to popular belief, nuts are not fattening
Many studies have shown that including nuts in the diet reduces the risk of weight gain. Eating nuts may also contribute to weight loss when eaten as part of an energy-controlled diet. Although nuts are a high-fat, high-energy food, there is some evidence that some of the fat in nuts is excreted, perhaps due to the structure of nuts. It’s also possible that nuts increase our use of energy when we eat them, or it may just be that the type of fat makes a difference to how nuts are metabolised. However it works, we wouldn’t recommend eating bucket-loads of nuts on the assumption their kilojoules don’t count, but we needn’t worry about weight gain if 30g nuts is part of our daily diet.
5. Nuts could also reduce our risk for type 2 diabetes
Some studies have shown a reduced risk of developing type 2 diabetes in women who regularly eat nuts or peanut butter, but not all studies have found the same results. While there is more to learn about nuts’ link to insulin response and the development of type 2 diabetes, it does appear that despite their high-fat content nuts do not worsen and may even improve insulin sensitivity in insulin-resistant people. More evidence is needed on this.