Health Benefits of Nuts: Raw vs. Roasted

Nuts, once shunned because of their high fat content, are now recognized as a nutritionally valuable food. The type of processing nuts undergo can affect their nutritional benefit; some alternative health professionals advocate eating nuts raw rather than cooked. Both raw and roasted nuts have benefits and drawbacks; most nuts sold as raw have actually been dried or soaked to remove harmful substances.

Nutrients

The nuts you buy in the store have generally been roasted, often in oil. Nuts naturally contain little sodium, but commercial manufacturers often add salt to their nuts. If you're watching your sodium intake, look for unsalted nuts. Oil-roasted nuts have more calories than raw nuts, but the difference isn't significant. The U.S. Department of Agriculture lists oil-roasted cashews as containing 580 calories per 100 grams, compared to 553 calories for raw cashews. The vitamins and minerals in the two products varied little, except for extra monounsaturated fat in the oil-roasted nuts. Monounsaturated fat is considered heart-healthy, since it helps lower cholesterol levels.

Phytic Acid in Raw Nuts

Raw nuts that haven't been soaked or dried contain substances that can cause harm. Plants such as nuts contain enzymes or other substances that protect the plant from germinating too soon or from being eaten by insects. Phytic acid in raw nuts protects the plant but can block your body from absorbing nutrients such as calcium, iron, magnesium and zinc. Soaking the nuts or drying them removes the phytic acid. Getting too much phytic acid in your diet can lead to nutritional deficiencies.

Bacteria in Raw Nuts

Raw nuts can also harbor harmful bacteria. For this reason, raw almonds, which have been implicated in several salmonella outbreaks, are no longer sold in California, the main almond producer in the United States. Roasting, blanching, lightly steaming and heating destroy salmonella bacteria. Peanuts can harbor aflatoxins, harmful fungi that, like salmonella, can cause severe illness. Roasting kills about 50 percent of the aflatoxins present in nuts; hand sorting after roasting to remove discolored nuts further reduces the number of contaminated nuts that make it to market, according to the International Food Safety Network.

Acrylamide

Roasting nuts also has its risks. Acrylamides -- chemicals that form in foods during the roasting process -- are somewhat associated with a few types of cancer. A systematic review published in the International Journal of Cancer in 2017 analyzed 32 studies on the chemicals and cancer risks. The researchers found that while acrylamide isn't linked with an increased risk for the most common cancers, it's modestly associated with kidney cancer, as well as ovarian and endometrial cancers in nonsmokers.