Start with the edible part

The kernel is not the shell.

This profile follows English walnuts as food. Halves, pieces and chopped kernels are familiar retail forms. Their hard outer shell is a different material, as is the separated oil. Choosing a food record begins with identifying which part and preparation you actually have. [1] [5]

The Wiki's Walnut Shell Powder page concerns a separate cosmetic raw material. It is not an alternative name for edible walnut meal. A shared plant name does not turn shell powder, oil and whole kernels into the same ingredient.

A serving in focus

What is in an ounce?

USDA's English walnut record, FDC 170187, lists an ounce as 28.35 g, about 14 halves. Calculating from that record gives approximately 4.3 g protein, 18.5 g fat and 1.9 g fiber, with a calculated energy value of 185 kcal. Most of its fat is polyunsaturated. These are reference values for that food, not for candied walnuts or a complete parfait. [1]

Walnuts contain ALA, an omega-3 distinct from EPA and DHA. [2]

Food structure in action

A calorie estimate is not a digestion experiment.

Baer and colleagues conducted a controlled crossover study in 18 adults. Participants ate a provided base diet during two three-week periods, one including 42 g of walnuts daily. Other foods were adjusted to keep the planned energy intake comparable. Researchers measured energy in the diets and in collected urine and stool. [3]

For the tested walnuts, measured metabolizable energy was approximately 146 kcal per 28 g, versus the study's predicted 185 kcal: about 21% lower. That is a different measurement from estimating energy using standard nutrient-conversion factors. The experiment concerned energy availability, not a guaranteed weight-loss effect or a skin outcome. [3]

The nutrition connection

Keep the whole food in view.

A kernel supplies fat within a mixture of protein, fiber and other components. Selecting one constituent cannot reproduce the whole food’s structure or composition.

This makes walnuts a useful bridge to the Wiki's separate topics on ALA, dietary fat and fiber. Pressed oil follows the fat fraction; the kernel retains a broader combination of food components.

In the kitchen

Protect the flavor you bought.

The California Walnut Board recommends keeping walnuts cold, using the refrigerator for near-term use and the freezer for longer storage. Transfer an opened bag to an airtight container, keep it away from strong-smelling foods and chop kernels close to when they will be used. These are freshness practices; follow the package's storage instructions as well. [5]

Walnuts are a tree-nut allergen. Check ingredient labels and avoid walnuts if they are among your diagnosed allergens, following your clinician's plan. [6]

From the cookbook manuscript

Mango + Blueberry Kefir Parfait

Chopped walnuts can contrast with soft fruit and creamy kefir. That texture explains their culinary role without making the bowl identical to a controlled feeding-study diet.