The message that nuts are a healthy food that can help lower bad LDL (low-density lipoprotein) cholesterol has been around for years. So why aren't we eating more? The surprise finding from a nut industry report on Australia's nut-eating habits is that most of us nibble them once a month or less, often on planes or at parties. Only 2 per cent eat them daily.
What's holding us back is the F-word: fat. We might know the fat in nuts, like the fat in foods such as olive oil and avocado, is healthy fat, but we're still keeping it at arm's length.
''We're clinging to the low-fat message that came out of the late '80s, and I think this is partly because the number of low-fat products available in the supermarket reinforces the idea that all fat is bad,'' says dietitian Lisa Yates of Nuts for Life, the industry organisation that provides nutrition information about nuts.
The paradox of nuts is that while they're loaded with fat (walnuts have 69 per cent fat, for instance, and pistachios about 51 per cent), studies show regular nut eaters don't appear to gain weight and nuts may help with weight loss if they're eaten in an energy-controlled diet. That's why Weight Watchers recommends a handful (30 grams) of unsalted nuts as a between-meal snack, because their fibre and protein content can quell hunger pangs.
But there might be more to nuts' positive effect on weight than filling power alone: other studies show some of the fat from nuts is excreted, not absorbed, a dietitian from Sydney's Nutrition and Wellbeing Clinic, Sue Radd, says. ''This means the assumed calorie contribution of nuts is actually less than food composition tables would tell us,'' she says.
''Some studies suggest we may not absorb up to 30 per cent of the fat in nuts, depending on the nut and how well it is chewed - chewing nuts less seems to be better from a weight-loss point of view.''
Nuts are also good for the heart. A number of studies suggest eating 30 grams of nuts at least five times a week reduces the risk of heart disease by 30 to 50 per cent, a result that's probably due to a mix of different effects on the body. One is that nuts naturally contain plant sterols (the same substances added to cholesterol-lowering margarines), as well as antioxidants that help keep arteries healthy. ''Mother Nature has supplied nuts with antioxidants, which prevent the fat turning rancid too quickly - and these antioxidants help prevent LDL cholesterol from sticking to the artery walls,'' Yates says. ''Nuts also contain an amino acid called arginine that's important for producing nitric oxide. This helps keep the artery walls relaxed, which in turn helps keep blood pressure healthy.''
If you're looking for sources of plant protein as an alternative to animal protein, nuts are a good option. In main meals, larger servings of nuts can stand in for meat or fish - think stir-fried vegetables and noodles with cashews or macadamias, or pasta tossed with crushed hazelnuts, olive oil and chillies.
Another bonus of adding nuts is they help lower a meal's glycaemic index (GI), which might help keep blood-glucose levels healthy. This could explain why eating nuts is also linked to a lower risk of type 2 diabetes, as well as better diabetes control for people who already have the disease.
Deciding where to store nuts - the fridge or pantry? - depends on how fast you eat them.
Everyday snacking nuts can be kept in the cupboard in airtight containers, if the turnover is quick. Yates advises storing nuts you use less frequently in airtight containers in the fridge or freezer. Just remember to bring refrigerated nuts to room temperature before eating - or warm them gently - to bring out their flavour.
Paula Goodyer blogs at smh.com.au/chewonthis.