Nuts are a concentrated source of nutrients, and typically provide all the major nutrients – carbohydrates, protein and fat — in a crunchy, convenient form. Nuts are highly valued as a convenience food and as a healthy snack alternative to chips or other processed foods. They are a part of the U.S. food guidelines for healthy eating, and due to their low water content, have a long shelf life.
Nuts are rich in calories, but they also provide plenty of nutrients like vitamins minerals, phytonutrients, phytosterols and antioxidants, making them a perfect example of nutrient-dense foods. Different varieties of nuts have unique proportions of nutrients and phytochemicals, so it is necessary to consume a variety of nuts to maximize the health benefits of nuts.
The majority of nuts, except peanuts (which is a legume), are tree nuts. Tree nuts include almonds, brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios and walnuts. Research has clearly underscored the benefits of regular nut consumption to lower the risk of heart disease. Several cohort studies including the Adventist study, the Iowa Women's health study, the Physicians' Health Study, and Nurses's Health study have shown a defined and consistent lowered risk of myocardial infarction and other heart problems. The health benefits of nuts are not only due to the presence of vitamins, minerals, fiber and unsaturated fats, but also due to the presence of phytonutrients.
Let's look briefly at the nutrition profile of various tree nuts. Nuts differ in the minerals, vitamins, and phytonutrient composition and therefore display different health benefits.
ALMONDS: Almonds are rich in monounsaturated fats, fiber and alpha-tocopherol. The important phytonutrients in almonds include catechin, protocatechuic acid, methylquercetin, p-hydroybenzoic acid, flavaonoids, vanillic acid, resveratrol and kaempferol. The phytonutrients in almonds are responsible for the cholesterol-lowering effect of these nuts. The presence of antioxidants prevents plaque formation, and decreases the risk of cancer and heart diseases. The presence of triterpenoids – betulinic, oleanolic and ursolic acid — is attributed to the anti-inflammatory and anti-cancer activity. Almonds are gluten-free and are popular in many gluten-free recipes.
BRAZIL NUTS: Brazil nuts are higher in selenium than any other food source, a single nut provides 160% of the U.S. RDA of selenium. Other important compounds include phenolics and flavonoids. Due to their high selenium content, brazil nuts exhibit anti-cancer effects. The presence of chief phytochemicals betacarotene and gadoleic acid are responsible for the powerful antioxidants and anti-cancer effects. Many studies have linked the consumption of brazil nuts to lower risk of cancer.
CASHEWS NUTS: Cashews are rich in heart healthy fats – oleic and palmitoleic acids — which help to lower bad cholesterol and raise the good cholesterol in the blood stream. Cashew nuts are particularly rich in the trace minerals copper, selenium and zinc. Only an ounce of cashews helps to eliminate many trace mineral deficiency in the diet. The phytonutrients in cashew include betacarotene, alpha-catechin, beta-sitosterol, gallic acid, cardanol, and epicatechin.
HAZELNUTS: Hazelnuts are an excellent source of manganese and a good source of copper, magnesium and iron. They are particularly high in vitamin E, and the phytonutrients in hazelnuts belong to the flavonol group and phytosterol groups. Flavanols demonstrate potent antioxidant, and the sterol groups display a cholesterol-lowering effect.
MACADAMIA NUTS: An ounce of macadamia nuts provides 24 mg of calcium, 36 mg of magnesium and 1 microgram of selenium. Magnesium and calcium are important for maintaining bone health. The nut is rich in phytosterol – beta-sitosterol that aids in lowering blood cholesterol — and the presence of selenium aids in antioxidant activity and heart protective effects.
PECANS: Pecans are naturally low in sodium, and high in zinc, iron, potassium, selenium and magnesium. The phytonutrients include betacarotene, caryatin, catechin and quercetin derivatives. An ounce of pecan nuts provides 28.6 mg, with beta-sitosterol contributing to 24.9 mg of sterols. A cup of pecans used in a recipe can provide 69.3 mg of calcium, 120 mg magnesium, 406 mg of potassium, and 4.5 mg of manganese (200% of DV).
PINE NUTS: Pine nuts contain omega-3 fat alpha-linolenic acid, oleic acid and omega-9 fat pinolenic acid. They are a significant source of B vitamins, and antioxidant vitamin E, as well as manganese and copper. About 100 g of pine nuts provides 8.8 mg of manganese and 251 mg of magnesium. Both the minerals are necessary for bone health, and manganese also plays a role in decreasing the symptoms of premenstrual syndrome.
PISTACHIOS: Pistachios are naturally low in sodium and high in potassium. Phytonutrients include betacarotene, beta-sitosterol, pectin, and stigmasterol, which aid in decreasing high cholesterol levels.
WALNUTS: Walnuts have an array of neuro-protective nutrients such as vitamin E, melatonin, folate, polyphenols, alpha linolenic acid (omega – 3) and several other micronutrients. The phytonutrients include juglone, betacarotene, ellagic acid, myricetin, tannin, and sakuranin.
The best way to reap the benefits from these nuts is to consume a variety of nuts rather than consuming any one type of nut alone. The presence of non-nutrient factors like phytosterols and phytochemicals contribute to the health benefits through different mechanisms.