While there is no such thing as an unhealthy nut, no two nuts are equal in nutritional composition. Almonds and walnuts are particularly prized. Almonds tend to have high levels of nutrients across the board and walnuts are high in the omega-3 ALA (alpha linolenic acid).
Studies show that including nuts in a meal may reduce the rise in blood glucose levels after you’ve eaten. A review of evidence conducted by industry nutrition organisation Nuts for Life suggests that eating a 30g-50g serve of nuts five times a week is enough to reduce your risk of heart disease up to 50%, lower total cholesterol levels by 10% and the risk of diabetes by 27%. Nuts have also been linked to a lower body mass index (BMI); despite their high energy and fat content, nuts have the amazing power of satiety and our bodies don’t absorb all the fat they contain; some is excreted as waste.
Nuts are a rich source of monounsaturated and polyunsaturated fats, which help control cholesterol. Macadamia nuts are highest in monounsaturated fats, which promote “good”cholesterol. Walnuts are the richest plant-based source of the omega-3 ALA, containing 100% of the adequate intake for women and 63% for men in just 13g (about five walnuts). Omega-3 can reduce the risk of heart disease.
Nuts are a good source of protein, which can help control appetite. They also provide the amino acid arginine, which the body turns into nitric oxide, causing blood vessels to dilate and remain elastic. Almonds contain the highest amount of arginine and provide the second-highest amount of protein after pistachios.
Fibre keeps you regular and can reduce cholesterol levels by preventing re-absorption in the gut. It also helps you feel fuller for longer. Hazelnuts contain the most fibre (10.4g/100g), followed by pistachios (9g/100g) and almonds (8.8g/100g).
Nuts provide a good hit of essential minerals, including magnesium, copper, zinc, selenium and potassium – all of which can play a role in protecting your heart. Magnesium also has protective properties against diabetes, high blood pressure and CVD – all factors in metabolic syndrome. Brazil nuts are highest in magnesium and selenium (an antioxidant); cashews are highest in zinc and copper, and pistachios are highest in potassium (which can help control blood pressure).
Vitamin E is a tocopherol – an antioxidant that can stop cholesterol from sticking to artery walls, which can lead to atherosclerosis, the leading cause of heart attack and stroke. Almonds are by far the nut highest in vitamin E.
Nuts contain plant sterols, which have been proven to reduce cholesterol absorption. Pistachios contain the highest amount of plant sterols, followed by almonds and pinenuts.
Fat is still fat
You may be happy to learn you won’t absorb all of the fat in nuts, but don’t nibble your way through a whole pack just yet. While nuts are full of vitamins and “good-for-you” fats, fat is the most energydense nutrient, providing 37kj per gram (by contrast, carbohydrate provides 16kj per gram). Even if you don’t absorb all this energy, you’re still going to get a big kilojoule hit. A small handful of nuts a day (about 30g, or 26 almonds) as part of a healthy diet will provide the health benefits without expanding your waistline.