Walnuts

In this Article (Index)

• Walnuts
• Health Benefits
• Risks: Allergies
• Nutrients and Bioactive Compounds.
• Phytochemicals
• Vitamins
• Minerals
• Oils and healthy fats
• Fiber
• Closing Comments

Walnuts

Walnut (Juglans regia) originated in the temperate regions of Europe and Asia and has extended to America, where it grows from Canada, and the US to Chile and Argentina in the south.

The global yearly production of walnuts is 3.63 million tons (M tons), followed by almonds with 3.18 M tons. (1)

Health Benefits

Approved Health Claims

The government authorities have approved health claims regarding walnuts in the European Union and the US.
The European Food Safety Authority authorized the following health claim in 2011:

• "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,"

In America, the Food and Drug Administration Authority (FDA) approved a 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.)"

Studies with walnuts show that eating between 21 and 75 g/day reduces the risk of cardiovascular disease and improves blood cholesterol levels. It also incorporates healthy dietary fiber, and fatty acids like omega-3 polyunsaturated fatty acids (PUFAs). (2)

Walnut intake (30 g per day) combined with a low-fat diet improved body weight, and fasting insulin levels. Walnuts also seem to provide roughly 20% less energy than their calculated energy content (in calories) suggesting that they provide a sense of fullness and satiety. Walnuts lower total cholesterol and triglyceride concentrations, as well as low-density lipoprotein or "bad" LDL cholesterol.

The antioxidants found in walnuts, its omega-3 α-linolenic acid, and the vitamin E (alpha-tocopherol) also exert anti-inflammatory effects which are also combined. (2),(3)

Risks: Walnuts and 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. (1)

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

The protein in nuts is responsible for allergies, walnuts can trigger adverse allergic reactions in some people.

The severity of walnut allergic reactions ranges from minor (itching in the mouth, and tongue) to severe reactions (anaphylactic shock; hives and swelling of the throat, asthma) and even death. (4)

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.

Nutrients and Bioactive Compounds

• Phytochemicals
• Vitamins
• Minerals
• Oils and healthy fats
• Fiber

Phytochemicals

Phenolic Compounds

Walnuts contain antioxidant compounds (polyphenols and flavonoids) such as vanillic acid, catechin, pyrocatechin, protocatechuic acid, epicatechin, syringic acid, gallic acid, juglone and cinnamic acid, ellagic acid, and rutin. (2) and the most abundant ones are chlorogenic, caffeic, p-coumaric, and ferulic acids.

Vitamins

As shown below, walnuts are very rich in vitamin E and different B vitamins. Below are the Vitamins found in walnuts, in mg per 100 grams. (2)

Minerals

Below are some minerals contained in walnuts expressed in mg per 100 grams. (2)

Oils and healthy fats

Walnuts have a very high oil content, only equaled by hazelnuts. The main components of walnut healthy oils are PUFAs, polyunsaturated fatty acids, followed by MUFAs, or monounsaturated fatty acids such as oleic acid. They are rich in Linolenic acid, a healthy omega-3, and have a low content of saturated fatty acids (mainly palmitic and stearic acids). (2)

Walnuts contain 64 to 66% lipids, and the breakdown is the following (g/100 g nut)

Fiber

Walnuts have a high content of fiber, (6.7%). (2); most of the fiber in walnuts is found in the skin (seed coat) surrounding the kernel.

Closing Comments

Walnuts are a healthy nut to add to your diet, the healthy oils, fiber, vitamins, and minerals promote cardiovascular health and regulate insulin levels.
Be well aware that tree nuts and peanuts can provoke severe food allergies.