For many years people falsely believed that eating too many nuts would cause weight gain, because "eating fats makes you fat." Thankfully, for the most part that misinformation has been corrected by the medical establishment, and they have admitted that refined grains and sugars are actually two of the biggest culprits of the current obesity crisis. Of course there are lots of unhealthy fats available, but natural healthy fats are extremely important for a healthy body, and nuts and seeds have lots of healthy fat. Nuts can also contain high levels of protein, and it is for that reason that they should be consumed in moderation, but enjoying about a handful of a variety of nuts every day is a great habit.
Before I go any further, let me say that peanuts are not a true nut--they are actually from the legume family along with beans--and should generally be avoided for a few reasons. Peanuts are relatively high in omega-6, skewing the proper omega-3 to omega-6 ratio that our bodies need. They are also frequently contaminated with a carcinogenic mold called aflatoxin, as well as being one of the crops most heavily contaminated with pesticides. (Try almond butter or other nut butters as a replacement for peanut butter.)
Tree nuts, however, are packed with healthy fats and lots of other important nutrients. They increase heart health, lower diabetic issues, and fight cancer. The main fat in Macadamia nuts (60% of its fat content) is the monounsaturated fat oleic acid--the same fat that makes olive oil so healthy--and it occurs in about the same level as that found in olives. Macadamia nuts are also high in vitamin B1, magnesium, and manganese. Pecans contain over 19 vitamins and minerals, they help lower LDL cholesterol, and promote healthy arteries. Walnuts are a good source of omega-3 fats and natural phytosterols, and they contain remarkable antioxidants that are very powerful at scavenging free radicals. Walnuts may help lower the risks of prostate and breast cancers; they boost heart health in people with diabetes and have reversed brain-aging in rats. Brazil nuts are a great source of selenium and contain powerful antioxidant-boosting minerals that also aid cancer prevention. Almonds, especially their skins, are rich in antioxidants typically associated with vegetables. One study showed that the amount of polyphenols in a one-ounce serving of almonds was comparable to the amount in one cup of steamed broccoli or green tea.
Seeds also contain an amazing array of nutrients. Pumpkin seeds are high in magnesium, zinc, and omega-3. They are important in maintaining prostate health (the main storage area for zinc) and immune function, and they are good for combatting diabetes. Sunflower seeds are rich in vitamin E, copper, B vitamins, manganese, selenium, phosphorous, and magnesium. They have high levels of phytosterols which are important for heart health, the immune system, and lowering cancer risks. Flax seeds are high in fiber, contain nine amino acids which form a complete protein, are a great source of plant-based omega-3 fats, and are a powerhouse against cancer, heart disease, and osteoporosis. Chia seeds have the best omega-3 to omega-6 ratio of seeds, are high in fiber (2 Tbsp.=10g fiber) and antioxidants as well as calcium, phosphorous, magnesium, and manganese. They are heart healthy, liver protective, anti-diabetes, anti-cancer, and anti-inflammatory. Sesame seeds are a good source of calcium, magnesium, zinc, fiber, iron, B vitamins, and phosphorous. They help lower blood pressure, protect the liver, and are linked to preventing arthritis, asthma, migraines, menopause and PMS symptoms, and osteoporosis. Grape seeds are beneficial for bone and dental health, blood pressure regulation, circulation, brain function, and prevention of diabetic and blood sugar disorders. Since huge quantities of the seeds would have to be consumed to gain these benefits, a grape seed extract supplement is more realistic. Bitter apricot kernels and other bitter fruit seeds like apple seeds contain Amygdalin (vitamin B17) which has incredibly powerful anti-cancer properties. There are cancer patients who have cured their cancer simply by taking Amygdalin. Laetrile is the concentrated pharmaceutical form of Amygdalin.
The best way to consume nuts and seeds is to buy them organic and raw--those salted, flavored varieties aren't the healthiest! For a great crunchy taste, simply soak them overnight (or 7 hours) in purified water with dissolved sea salt (1 Tbsp. salt per 4 cups nuts/seeds), then dry them in a dehydrator or in an oven set at the lowest temperature (150 degrees or under) for 12-24 hours. Soaking helps neutralize the enzyme inhibitors that affect digestion and nutrient absorption. I prepare large batches of nuts and seeds this way then mix them with organic dried fruit, organic coconut flakes, and even organic dark chocolate or cacao nibs.
They make a wonderful healthy snack, so go nuts with your own combinations!