Brazil Nuts – Proceed with Caution Eating too many
Brazil nuts, cashews and macadamia nuts are higher in saturated fat. Too much of this can contribute to raised cholesterol levels, so only eat them occasionally. Chestnuts are an exception – they're lower in all types of fats and higher in starchy carbohydrate than other nuts.
Raw cashews contain urushiol, a resin that is toxic if ingested and can cause rashes or burns if it contacts the skin. To remove this substance, cashews must go through a rigorous roasting or steaming process to ensure they are safe to eat.
Brazil Nuts – Proceed with Caution
Eating too many Brazil nuts can lead to toxic levels of selenium in the body (selenosis) and cause symptoms such as bad breath, diarrhea, nausea, skin rashes/lesions, nerve pain and fatigue. In rare cases, very high levels can cause kidney failure, cardiac arrest and even death.
Truly raw cashews are not safe to eat, as they contain a substance known as urushiol, found in poison ivy. Urushiol is toxic, and contact with it can trigger a skin reaction in some people. Cashew kernels are often sold as “raw” in stores, but these have been steamed. This removes the toxins.
Macadamia Nuts, Pecans
As long as you're practicing proper portion control and not downing handfuls at a time, says Caplan, any kind of raw, plain nut will give you a good dose of healthy fats and nutrients.
Pine Nuts
Pine nuts are pretty sustainable, and cause no harm to land, soil, air, water and animals as long as no pesticides are used.
Most of the nuts contain compounds like phytates and tannins, which make it difficult for our stomach to digest them. Nuts also contain different kinds of fat, which can lead to diarrhea.
Both types of almonds -- bitter and sweet -- have amygdalin, a chemical compound that can turn into cyanide, but bitter almonds have the highest levels by far. Sweet almonds are safe to snack on, but eating untreated bitter almonds can cause cramps, nausea, and diarrhea.
As can be observed, arsenic in the form of As(III) ranged from 0.7 ± 0.2 to 12.7 ± 0.9 ng g-1; the lowest level was obtained in peanuts, the highest in cashews and in white walnuts.
The amounts of As(III) tended to be higher in non-processed nuts (cashews, almonds, pine nuts, walnuts) than in processed samples (salted peanuts, sunflower seeds).
Almonds, macadamia nuts, hazelnuts and pecans also appear to be quite heart healthy. So are peanuts — though they are technically not a nut, but a legume, like beans. It's best to choose unsalted or unsweetened nuts. Adding salt or sugar to nuts may cancel out their heart-healthy benefits.
Generally the highest contents of metals were found in Brazil nuts (the highest contents of Ba, Ca, Co, Se and Sr), pecans (the highest content of Cr and Mn), chestnuts (the highest content of K and Tl), pistachios (the highest contents of As and Li), and pumpkin seeds (the highest contents of Mg, Mo, P and Zn).
People who are allergic to nuts should not eat walnuts. If the person develops a rash or hives or difficulty breathing after eating walnuts, medical attention should be sought. Children should not consume pieces of nut, or they should be supervised while doing so, as this can lead to choking.
Walnuts: Have the highest amount of alpha-linolenic acid (ALA) than any other nut. ALA is well known for its anti-inflammatory effects.
In botany terms, nuts are strictly a particular kind of dry fruit that has a single seed, a hard shell, and a protective husk. Chestnuts, hazelnuts, pecans and walnuts fit the true definition of a nut. Peanuts and almonds do not meet the botanical definition of a true nut.
Macadamia nuts are the most expensive nuts in the world, at $25 per pound. The flowering macadamia trees originated in northeastern Australia and take 7 to 10 years to begin producing nuts. The nuts can only be harvested a few times a year.
Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7μg kg(-1) by using the pyrolysis of sample after the extraction of the nut fat.
Bitter almonds grow as a cyanogenic plant, meaning it contains cyanide. The almonds are fine once they're cooked or roasted, but they are not safe to eat raw. The raw form of the bitter variety is actually illegal in the U.S., but it's more prevalent in certain parts of Europe.
High Oxalate Content: Cashews have a relatively high oxalate content. When eaten in large quantities, this can lead to kidney damage and other chronic health problems.