Go nuts, eat nuts!

Nuts may have gotten a bad rep because they're a concentrated source of calories and fat. Interestingly, its mainly their fat that provides so many of their health benefits.

Nuts are a great source of the healthy monounsaturated and polyunsaturated fats, which help lower LDL (bad) cholesterol levels, particularly when they replace saturated fat in the diet. Replacing 5% of total calories as saturated fats with unsaturated fats can help reduce your risk of heart disease by 40%!

Macadamias, cashews, almonds, pistachios, peanuts and pecans are rich in monounsaturated fat, while walnuts, hazelnuts, pine nuts and brazil nuts are rich in polyunsaturated fat (omega 3) .

Aside from providing a healthy dose of unsaturated fats, nuts are also a source of fibre (making nuts a great filling snacks), protein, vitamin E (an antioxidant), vitamin B6, as well as niacin and folic acid, magnesium, zinc, selenium (just one brazil nut provides the whole day’s recommendation for selenium!), phytochemicals (shown to have antioxidant properties) and plant sterols (shown to improve cholesterol).

In 2003, the American FDA released the health claim: " Scientific evidence suggests but does not prove that eating 1.5 oz per day of most nuts as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease".

The research

It's been shown that eating 30 grams (1 oz) of nuts five times per week has been shown to be effective in reducing the risk of heart disease by 30 to 50% and lowering cholesterol levels by 10%.

In 1996, the Iowa Women's Healthy Study found that women who ate nuts >4 times a week were 40% less likely to die of heart disease.

Part of the Nurses' Health Study, published in the British Medical Journal in 1998, looked at the health of more than 86,000 women. It found that those who ate 142 grams (five ounces) of nuts per week were 35% less likely to develop heart disease than women who ate less than one ounce per week. In the 2002 U.S Physicians Health Study, Harvard researchers found that men who ate nuts two or more times per week were 47% less likely to die of a heart attack and 30% less likely to die of heart disease than men who rarely ate nuts.

The 1992 Adventist Health Study, which examined the diets of more than 31,000 Seventh Day Adventists, found that participants who consumed nuts more than four times per week experienced 51% fewer heart attacks compared to those who consumed nuts less than once per week.

How much should you eat?

Despite their healthy nutrient profile, nuts are still a concentrated source of calories in the diet. Instead of adding nuts to your diet on top of everything else you eat in a day, eat them to replace other less-healthy foods, such as foods high in saturated or trans fat.

A serving of nuts is 60 ml, 1/4 cup or about 30 grams. For nut butters, the appropriate portion size is 30 ml, or about two tablespoons. Try to include a serving of nuts or nut butters at least 3 times a week.

Finally, to maximize the health benefits that nuts have to offer, you're better off enjoying them on their own instead of drenched in salt or smothered in chocolate or added fat. Added salt, sugar and fat can offset any benefits that nuts have to offer.

Effects of processing on nuts

I have heard that roasted nuts are unhealthy. However, there are no legitimate references for this. The only source I found is from whfoods.org that states that:

Roasting nuts at a temperature higher than 170F (as in commercially roasted nuts) will cause a breakdown of their fats and the production of free radicals.

I have read that as long as nuts are dry-roasted (commercial or not) their nutritional value will be much the same as raw nuts, but with a slight reduction in B vitamins due to the heating process. On the other hand, nuts roasted in oil contain 10 per cent more calories than dry-roasted or raw varieties and they are often salted. Watch out for nuts roasted in coconut or palm oil (read the ingredients)- these nuts will be higher in saturated fats.

Nuts contain natural fats so to keep them in the best condition and slow down their oxidation, store them in an airtight container in your fridge or freezer. Nuts can be refrigerated up to four months and frozen up to six months. Nuts commonly come packaged in foil or plastic packets from the supermarket. Foil packaging protects the fats in the nuts from oxidation and gives them a longer shelf life.

Sources:
http://www.healthyfoodguide.com.au/index.php?option=com_content&task=view&id=101&Itemid=50 ;
http://www.cbc.ca/news/background/food/nuts.html ; http://www.whfoods.com/genpage.php?tname=george&dbid=10