Are raw nuts more healthy than roasted nuts?

by Jennifer Bowden / 19 August, 2018
RelatedArticlesModule - Raw nuts roasted nuts

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Most of us are getting the message that unroasted, additive-free nuts are healthiest.

Every silver lining has its cloud. And roasting certainly has a magnificent silver lining. French scientist Louis Camille Maillard first described the high-temperature chemical reaction that gives foods such as seared lamb roasts and fresh-baked bread and cookies their distinctive flavour. But back to that cloud.

When we roast almonds, undesirable changes can occur, but those aren’t related to mineral content. In fact, roasted almonds have the same proportion of minerals per 100g as raw nuts.

Roasted almonds may have more or less of some vitamins, however. For example, roasted almonds had more folate but significantly less vitamin B1 (thiamine) when assessed for the New Zealand Food Composition tables. The same trend is seen in food composition data from the US, where most of our almonds originate.

And it makes sense that roasting could cause the loss of heat-sensitive vitamins such as thiamine (folate is less sensitive to heat). But the problem with this data is the raw and roasted almonds weren’t necessarily from the same batch. So, nutrient differences between the two groups of nuts may have existed before roasting.

Still, there’s more to nuts than just vitamins and minerals. They provide a concentrated source of unsaturated fat and fibre, too. And eating nuts regularly is a simple way to boost our intake of nutrients and healthy fats.

Frequent nut consumption may play a role in protecting us from cardiovascular disease, coronary heart disease, myocardial infarction (heart attacks) and sudden death. Clinical studies suggest this is largely due to reductions in total cholesterol, LDL-cholesterol and apolipoprotein B concentrations, according to the Heart Foundation.

And the good news is roasted almonds improve total and LDL cholesterol just as well as raw almonds.

However, the biggest issue with roasted almonds is the potential presence of acrylamide, a probable human carcinogen found in animal studies as a cause of cancer.

Acrylamide can form during the browning reaction between reducing sugars (glucose) and amino acids (asparagine) at cooking temperatures above 120°C. How much forms depends on the cooking time and temperature; higher temperatures and longer cooking times generally create more acrylamide.

A number of other foods contribute more acrylamide to our diet than roasted nuts, however. For New Zealand adults, 27% of exposure comes from potato products (hot chips, roast potatoes, crisps), 15% from bread (fresh or toasted), 12% from breakfast cereals and 17% from beverages (beer, tea and coffee). For children, biscuits ranked fourth after potato products, breakfast cereals and bread.

Unprocessed nuts and nut butters without additives such as salt, sugar or fat provide the greatest health benefits. If you prefer nuts roasted, in the scheme of things their acrylamide content makes only a small contribution to our total acrylamide intake. But if you prefer to minimise your acrylamide intake, roast your own almonds at a low to medium heat (about 100°C) in a shallow dish in the oven to limit acrylamide formation. Stir them occasionally and cook them until they reach the desired crunchiness. Store in a cool, dry, dark place.

Most people seem to be getting the message about the health benefits of raw nuts. According to Kristina McCalman, resident nut expert at Alison’s Pantry, we are eating more raw nuts than a decade ago. In particular, we’re consuming more raw almonds, walnuts and nut mixes.

Raw nuts are more commonly served as snacks, but it may also be that trends such as “raw” baking and paleo-style eating – which encourage raw-nut consumption – are having an effect, too. In the end, though, our most popular nut is still the roasted salted cashew.

This article was first published in the August 4, 2018 issue of the New Zealand Listener.

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