It’s been over 10 years since I started working for Nuts for Life and the Australian Tree Nut Industry. At the time I couldn’t get over the fact that many people thought nuts were unhealthy. I remember thinking how could anyone think something that grows on a tree could be unhealthy?!
Well fast forward 10 years and eating nuts is now a daily “must do” which is fantastic but we still get asked the odd question and the one which is popular is “I love the tasted of roasted nuts over raw but does roasting nuts doing something to the nutrients or health benefits?”
Let’s take a look at what happens when nuts are roasted.
Nuts are commerically roasted in different ways. Oil roasted usually means nuts are submerged in hot oil. Dry roasting can occur either as a single layer of nuts on a conveyer belt through an oven or rolling around in a mini rotating drum like a cement mixer over flame.
Roasting nuts in general modifies some of the nutrients. For instance, B group vitamins are not heat stable so levels are reduced during roasting.However since we get most of our B group vitamins from breads and cereal products this is not usually a problem. Roasting also reduces the water content so concentrates minerals such as potassium, magnesium, manganese and copper. (Want a great and simple green smoothie recipe? Check it out in Mamamia TV’s video below. Post continues after video.)
Surprisingly there are only small differences in the amount and type of fats. Nuts are so dense they can’t absorb a lot of extra oil even if submerged in oil unlike potato for instance when making chips. Industry members tell me nuts absorb about 2 to 5 per cent of the oil they are roasted in.
Some polyunsaturated fats can be converted to saturated fats when heated but in nuts the change is only about 10 per cent. Is this clinically relevant since saturated fats can increase blood cholesterol?
Probably not – two clinical trials have reviewed this. The cholesterol lowering effects of roasted almonds versus raw almonds were studied by researchers in the US and they found roasted almonds reduced total and LDL blood cholesterol similarly to raw almonds (1). Another study with roasted peanuts found similar results (2).
One major difference with oil roasted nuts is that they are usually then also salted.
Nuts and blood pressure
Health authorities recommend reducing the salt/sodium content of diets to help reduce the risk of cardiovascular disease and high blood pressure. So do salted nuts have a positive or negative effect on health?
A meta analysis of many nut studies (3) and a specific pistachio clinical trial (4,5) (where half the pistachios given were salted about 15g a day but as part of a lower sodium diet overall) indicate that nuts (and specifically pistachios) appear to have a good effect on blood pressure. Nuts appear to help keep blood vessels elastic and reduce inflammation which may explain this (6). Nuts are also sources of potassium and contain an amino acid called arginine which is involved in blood vessel health. (Post continues after gallery.)
The large population studies that found a link between regular nut consumption and a reduced risk of heart disease were done in 1990s-2000s. At a time when a large portion of nuts sold and eaten were salted nuts.
Researchers of these studies didn’t ask participants if they ate raw or salted nuts just “nuts”. And in general eating “nuts” at least five times a week resulted in a 30-50 per cent reduced risk of heart disease (7-11).
Flavour benefits of roasted nuts
Many people tell us they enjoy the flavour of roasted nuts more and studies have analysed and identified the flavour compounds of roasted nuts that makes them... well... nuttier (12-15).
So if someone has an overall healthy diet does it matter if they enjoy salted nuts on occasion? I don’t think so as the effect of the salt may be offset by the other heart health nutrients that nuts contain such as: healthy fats, fibre, vitamin E, folate, potassium, selenium, manganese, copper, plant sterols and arginine.
For the most part roasted nuts have a flavour profile people enjoy and if this means they eat a handful of nuts more regularly then that’s good for their health overall.
What do you prefer? Roasted or raw nuts?
This post originally appeared on Dr. Joanna. You can view the original post here.