Nuts: Properties & Benefits

In this Article (Index)

• What are Nuts?
• Health Benefits of Nuts
• Approved Health Claims
• Nuts as part of a Healthy Diet
• Nutrients in Nuts
• Fatty Acids (oils and fats)
• Protein
• Vitamins
• Minerals
• Dietary Fiber
• Phytochemicals
• Risks: Allergies

What are Nuts?

Nuts are edible dry fruits.

Tree nuts have a hard outer shell that protects an inner edible plant seed. True tree nuts include chestnuts, macadamia nuts, and hazelnuts. Then come the "drupes", which are fleshy fruits with a central seed like plums, and peaches, where we eat the fleshy sweet fruit and discard the seed, also known as a pit. However in drupe-type nuts, the pit contains an edible kernel or "nut", this is the case with almonds, pecans, walnuts, pistachios, and pecan nuts. The last type of tree nut is a seed, like pine nuts.

Then come peanuts which despite their name, are a legume, and like beans, peas, and lentils, they grow in pods on a bush.

The most consumed nuts are tree nuts like hazelnuts (Corylus avellana), almonds (Prunus dulcis), cashews (Anacardium occidentale), walnuts (Juglans regia), chestnuts (Castanea sativa), pistachios (Pistacia vera), and peanuts (Arachis hypogaea).

Nuts contain a wide range of nutrients (protein, fat, carbohydrates), minerals, vitamins, dietary fiber, and plant-based chemicals (carotenoids, phytosterols, squalene, and polyphenols). ((8))

Nuts are an important component of the Mediterranean diet and are mentioned as one of the foods in the Dietary Guidelines for Americans (2020-2025).

Detailed Information on Different Types of Nuts

This article gives an overview of nuts, we have written specific pages on different nuts, with full information on their health benefits, nutrients, properties, and risks.

Click on the links below to visit these pages:

• almonds
• chestnuts
• walnuts
• hazelnuts

Health Benefits of Nuts

Eating nuts regularly has beneficial health effects, and reduces hypertension, obesity, diabetes, and cardiovascular diseases. It lowers inflammation, visceral fat, high blood sugar levels, insulin resistance, and metabolic syndrome. (7)

Below are just a few studies mentioning the benefits of consuming nuts.

A 2013 study (PREDIMED - PREvención con DIeta MEDiterránea) (1) investigated the effects of high nut consumption and mortality in subjects with a high cardiovascular risk in Spain. They analyzed data from 7,216 patients aged 55 to 88 assigned randomly to three groups: (1) Mediterranean diet supplemented with olive oil, (2) Mediterranean diet supplemented with nuts, and (3) the healthy low-fat control diet that served as a comparison. They were followed up for an average of 4.8 years. A nut serving was 28 g (1 oz) of tree nuts or peanuts.

The study showed that the risk of total mortality was greatly reduced in the group eating a Mediterranean diet supplemented with nuts compared with the other two groups: 62% in the 1-3 servings of nuts per week segment, and 63% in the 3 and more servings of nuts per week. For those eating a Mediterranean diet with extra virgin olive oil, who also ate nuts as part of their diet, the risk reduction was 21% in the 1-3 nut servings per week group, and 37% in the +3 servings per week group.

These findings are similar to those reported in the Iowa Women's Health Study (2) where those who consumed nuts 2 or more times a week had a 12% lower mortality risk than those eating nuts once a month.

A 2011 Dutch study (3) after following 120,852 men and women for 10 years showed that the subjects in the highest quartile of nut consumption (top 25%) had a lower risk of all-cause mortality: 8% for men and 5% for women compared with those in the lowest 25% of nut consumption.

The Nurses' Health Study data with an 18-year follow-up showed an association between consuming nuts 2 or more times a week and a 14% risk reduction of all-cause mortality. (4)

Nut consumption in America is low compared to Spain as only 10% of the Iowa Women subjects and 10% of the nurses consumed nuts 2 or more times a week, and the Dutch subjects in the top 25% only consumed 11.1 g per day (men) and 6.2 g (women). As a reference, half a walnut weighs 3.5 g.
In the Spanish PREDIMED study, on the other hand, 32% of the participants consumed nuts more than 3 times per week.

Interestingly, an analysis of the PREDIMED study (5) mentions nuts' cancer-protective effects: a reduction in cancer mortality was noticed in those eating three or more servings per week of walnuts (not any type of nut, but walnuts).

A 2022 analysis using data from 3,092 subjects of the Coronary Artery Risk Development in Young Adults (CARDIA) study (6) which followed participants for over 20 years, found that:

• Those who ate walnuts had a better CVD risk profile than other nut eaters, and those who didn't eat nuts.
• "Walnut and other nut consumption was associated with better CVD risk factors."

Interestingly those who consumed nuts, and walnuts had a higher degree of alignment with the 2015-2020 Dietary Guidelines for Americans, meaning that they also ate healthier diets. They also had lower BMI (Body Mass Index), waist circumference, lower blood pressure, and triglyceride levels. Their weight gain since the beginning of the study was lower than that of other participants, and they also had lower fasting blood glucose than those who didn't consume nuts.

Approved Health Claims

After reviewing solid scientific evidence, the European Union, and the US have approved some health claims regarding nuts.

In 2011, in the EU, the European Food Safety Authority authorized the following health claim:

• "Walnuts contribute to the improvement of endothelium-dependent vasodilation".
  "In order to obtain the claimed effect, 30 g/day of walnuts should be consumed daily. These amounts can be consumed in the context of a balanced diet. The target population is the general population,"

The American Food and Drug Administration Authority (FDA) approved a health claim for tree nuts and peanuts, including walnuts in 2003, finding that they reduced the risk of cardiovascular disease, allowing a claim stating that intake of most nuts as part of a diet low in saturated fat and cholesterol may reduce the risk of CVD. In 2004 another claim was approved by the FDA specifically for walnuts.
The Dietary Guidelines for Americans issued by the USDA and the HSS have recommended eating nuts as part of a balanced diet since the 1990s.

The FDA approved yet another health claim in 2017 for most nuts: "Scientific evidence suggests but does not prove that eating 1.5 ounces per day of most nuts, such as walnuts, as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease. (See nutrition information for fat content.)"

Nuts as part of a Healthy Diet

The Dietary Guidelines for Americans, 2020-2025, or DGA prepared by the USDA and HSS includes nuts in the healthy diet it recommends; it mentions them as part of Protein foods, one of the core elements that make up a healthy diet: tree nuts and peanuts; it also considers them a source of healthy oils naturally found in food. It recommends nuts because they are "nutrient-dense". The DGA also cautions that nuts should be eaten unsalted, and not as "butters". It suggests consuming 5 oz. per week, and in a breakfast example, it includes 4 walnuts.

Nutrients in Nuts

Each type of nut has its own concentration and mix of oils, protein, amino acids, and phytochemicals. For instance, almonds and hazelnuts are rich in vitamin E, Brazil nuts in selenium, walnuts contain more phenolic compounds while pistachios have high levels of carotenoids; peanuts are particularly rich in phytosterols. (3)
This section will give an overview of each of the nutrients that make up nuts.

Fatty Acids (oils and fats)

The ratios of different tipes of fats and oils in nuts depend on the variety, they all contain varying levels of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs), including omega-3 fatty acids.

Almonds, hazelnuts, and cashew nuts have the highest ratio of MUFAs to SFAs which is 10 to 1 in hazelnuts; the lowest ratio is found in Brazil nuts. Macadamias have the highest MUFA/PUFA proportion. Walnuts have the highest level of PUFAs, and α-linolenic acid (an omega-3), making up more than 47% of the total PUFA content. (3)

Protein

Almonds, peanuts, and pistachios have high protein levels, while chestnuts have the lowest ones. Nuts don't contain all essential amino acids like animal proteins, however, they do have large quantities of amino acids like arginine which reduces the risk of cardiovascular disease and inflammation while also promoting immune response.
Combining different types of nuts provides a different mix of essential amino acids. (8)

Vitamins

Tree nuts and peanuts contain vitamins (C, B1, B2, B3, B6, and E) and are a good natural source for them.

Minerals

Nuts are rich sources of minerals like magnesium (Mg) and potassium (K) as well as copper (Cu). They have heart protective effects (Mg and Cu against coronary disease), and potassium against high blood pressure. Cashew nuts and pistachios are particularly rich in K.

Zinc and iron are found in most nuts, especially in cashews, almonds, and pine nuts. Calcium is highest in almonds, but in general, nuts don't have high amounts of it.

Dietary Fiber

Dietary Fiber is found in all nuts, has many positive health effects, and improves the diversity of the Gut microbiome.

Almonds with 12.5% have the highest fiber content of all tree nuts while peanuts have even more fiber content. (3)

Phytochemicals

Nuts have a high content of plant-based bioactive compounds like polyphenols, that act as anti-inflammatory and antioxidant agents. They have a beneficial effect on blood cholesterol levels and have cardioprotective, neuroprotective, and antidiabetic, properties.

Each nut species has its own specific phenolic profile and content. (8)

Processing affects nuts

How nuts are processed before they are consumed can modify their antioxidant composition. Nuts can be blanched, peeled, roasted, or milled. It may cause a reduction in antioxidant properties in hazelnuts and walnuts while increasing it in pistachios and almonds. The skin is where most polyphenols are located so peeling or roasting can affect them too as is the case with almonds and peanuts; in pistachios, most of the antioxidants are destroyed when their hard shells are cracked. (8)

Risks: Allergies

Tree nuts are one of the Big Eight food groups responsible for over 90% of food allergy cases in the US. The other seven allergy-causing foods are peanut, milk, shellfish, soy, wheat, egg, and fish.

Tree nut allergies are usually more severe and life-threatening than the allergic reactions caused by eggs, or milk, which are normally mild and short-lived.

Except for chestnuts, all main types of nuts are capable of setting off allergic reactions in susceptible people, these allergy-triggering nuts are: almonds, cashew nuts, hazelnuts, macadamia nuts, peanuts, pecan nuts, pine nuts, pistachio, and walnuts. (8)

The Severity of allergic reactions provoked by tree nuts and peanuts ranges from minor (itching in the mouth, and tongue) to severe reactions (anaphylactic shock; hives and swelling of the throat, asthma) and even death.

Take care, allergic reactions can be very serious

Check the food label for the listed allergens ("may contain...", and "Contains..."), it should mention tree nuts (for example: almonds, cashews, pistachios, pecans, walnut, hazelnut) and peanuts (also called ground nut by some). The American FDA also requires the specific identification of tree nuts such as coconut, shea nut, and pine nuts. Also check the "processed" text which could read: "processed at a facility that handles nuts".
When in doubt, avoid the product, and always read the label for ingredients and the text in the "Precautionary allergen labeling" (PAL). Eating out: Ask the waiter questions.

Closing Comments

Adding an assortment of tree nuts and peanuts to your diet as recommended by the Dietary Guidelines for Americans will provide you with plant-based vitamins, antioxidants, anti-inflammatory agents, minerals, and protein plus healthy heart-protecting fats.