The key with nuts is simply not to over eat them. They are highly concentrated in both their calories and their nutrients, so you only need a small handful at a time. Eating a variety of nuts appears to be the best way to get all the different benefits each nut has to offer.  
 
1. When it comes to nuts, the walnut is the king. It's a great source of the healthy omega-3 essential fatty acids, which have been found to protect the heart, promote better cognitive function, and provide anti-inflammatory benefits for asthma, rheumatoid arthritis, eczema and psoriasis.  
 
Walnuts also contain the antioxidant compound ellagic acid, which is known to fight cancer and support the immune system. In a study in the August 2003 issue of Photochemistry, researchers identified 16 polyphenols in walnuts, including three new tannins, with antioxidant activity so powerful they described it as "remarkable."
 
2. Just a quarter cup of almonds contains nearly 25 percent of your needed daily value of the important nutrient magnesium, plus is rich in potassium, manganese, copper, the antioxidants vitamin E and selenium, and calcium. In fact, a quarter cup of almonds has almost as much calcium as a quarter cup of milk.
 
They're also great for the colon. An animal study on the effects of almonds on colon cancer found that animals (which were exposed to a colon-cancer-causing agent) given whole almonds had fewer signs of colon cancer than animals given almond oil or no almonds. Researchers suspect the benefit may be due to almonds' high fiber content.  
 
Plus, almonds are one of the best nuts for lowering cholesterol because 70 percent of the fat they contain is the healthy monounsaturated variety, which has been shown to help clear arteries.
 
3. Cashews are lower in fat than most nuts, and 65 percent of this fat is unsaturated fatty acids. Of this, 90 percent is oleic acid, the heart-healthy fat found in olive oil.
 
Plus, cashews are rich in copper, magnesium, zinc, iron and biotin but must be eaten with out salt for any real health benefit.
 
4. Pecans are excellent with over 19 vitamins and minerals including vitamins E and A, folic acid, calcium, magnesium, copper, phosphorus, potassium, manganese, several B vitamins and zinc.  
 
Research from Sue Taylor, R.D., director of nutrition communication for the National Pecan Shellers Association, "Recent clinical research studies evaluating the impact of pecans on serum cholesterol have found pecans can significantly help lower blood cholesterol when consumed as part of a heart-healthy diet."
 
5. Brazil nuts are extremely nutrient-rich and contain protein, copper, niacin, magnesium, fibre, vitamin E and selenium. Selenium is a powerful antioxidant that works to neutralize dangerous free radicals. A study at the University of Illinois even found that the high amounts of selenium in Brazil nuts may help prevent breast cancer.
 
6. Macadamia Nuts are high in protein, fibre, healthy monounsaturated fats, potassium and magnesium. A study done at Hawaii University found that people who had added macadamia nuts to their diets for just one month had total cholesterol levels of 191, compared to 201 for those eating the typical American diet. The largest change was found in the LDL (bad) cholesterol.