Raw power

Nuts are packed with nutrients and fats that benefit heart and gut health. But those roasted at high heat, while tasty, can be risky.

- Jennifer Bowden

Question: I was interested to read about the gut-health benefits of peanuts in Nutrition Bites and wondered if this finding applies equally to raw and unsalted roasted peanuts?

Answer: Eating just 3-4 small handfuls of nuts a week can decrease the risk of coronary heart disease by about 20%, according to the Heart Foundation. Moreover, recent research affirms that regular nut consumption promotes a healthy gut microbiome, which is beneficial.

However, when nuts are roasted, undesirable compounds can form. So, from a health perspective, is it best to avoid all roasted nuts?

The biggest issue with roasted nuts (particularly almonds) is the potential presence of acrylamide, a possible human carcinogen that has been found in animal studies to cause cancer.

We love the distinctive flavours that occur when nuts are cooked by high heat, but this can also produce acrylamide, which can form during the browning Maillard reaction between reducing sugars (glucose) and amino acids (asparagine) at temperatures above 120°C. How much forms depends on the cooking time and temperature, with higher temperatures and longer cooking times generally creating more.

However, several other foods contribute more acrylamide to our diet than roasted nuts. For New Zealand adults, potato products (hot chips, roast potatoes, crisps) are the most significant contributor, followed by bread (fresh or toasted), breakfast cereals and then beverages (beer, tea and coffee). When it comes to children, biscuits take that fourth spot in place of drinks.