About Walnuts

Walnut FAQs

Do you think all nuts are the same? Do you wonder if heating walnuts affects their nutritional value? Here are answers to some of the most popular questions.

Q. I have heard walnuts are good for me. Aren’t all nuts the same?

A. Walnuts are unique compared to other nuts because they are predominantly composed of polyunsaturated fatty acids (PUFA, both omega-3 and omega-6) rather than monounsaturated fatty acids (MUFA), which are present in most other nuts. Walnuts are the only nut that contain a significant amount of ALA, the plant based source of omega-3 fatty acids. A one-ounce serving of walnuts provides 18 grams of total fat of which 13 grams are PUFA and which 2.5 grams are ALA, as well as other health-promoting nutrients and bioactive components.

Clinical studies have shown promise in the areas of heart health, diabetes, cancer, and metabolic syndrome.

Q. I use the 2005 MyPyramid to help me make the right food choices for a healthy diet. Where do walnuts fit in?

A. Including healthy fats in the diet is one of the key messages of the individualized MyPyramid food guidance system. The new MyPyramid symbol illustrates recommendations from the 2005 Dietary Guidelines for Americans where an emphasis to consume more polyunsaturated fat (and less saturated and trans fat) in order to achieve a healthy diet is made. Specific guidelines were given to increasing intake of essential fatty acids, including omega-3 fatty acids. Plant sources of polyunsaturated omega-3 fatty acids such as walnuts are specifically noted. 

Q: I read a lot about the Mediterranean Diet, what exactly is it?

A: The Mediterranean Diet is actually many diet patterns that hail from various countries. According to the American Heart Association the common Mediterranean dietary pattern has these characteristics:

  • high consumption of fruits, vegetables, bread and other cereals, potatoes, beans, nuts and seeds
  • olive oil is an important monounsaturated fat source
  • dairy products, fish and poultry are consumed in low to moderate amounts, and little red meat is eaten
  • eggs are consumed zero to four times a week
  • wine is consumed in low to moderate amounts
  • Walnuts are a traditional component in this dietary pattern.

Q. Are the omega-3 fatty acids in fish the same as the ones in walnuts?

A. The omega-3 fatty acid alpha linolenic acid (ALA) is the precursor or “parent” to the two long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Walnuts contain ALA and fatty fish contain EPA and DHA. Metabolic reactions enable ALA to be converted into EPA and DHA. A recent study published in the American Journal of Clinical Nutrition looking at whether walnuts (providing ALA) and fatty fish (providing EPA and DHA) have similar effects on specific blood markers associated with Coronary Heart Disease. The study found that a diet including walnuts was more powerful in reducing total and LDL (bad) cholesterol when compared to fatty fish. Healthy individuals who consumed walnuts reduced their total cholesterol by 5.4% and LDL by 9.3% translating to an 18.6% decrease in risk of Coronary Heart Disease (CHD). When they consumed fatty fish, HDL (good) cholesterol increased and triglycerides decreased. 

Q. Is there a dietary reference intake (DRI) for alpha linolenic acid?

A. Although the ideal intakes of omega-3 fatty acids are unclear at this time, the acceptable range of alpha linolenic acid (the plant based source of omega-3 fatty acids) is estimated to be 1.3 to 2.7 grams per day on the basis of a 2000 calorie diet, according to the Dietary reference Intake report by the Food and Nutrition Board of the National Academies' Institute of Medicine (IOM). As of 2007, the FDA currently recognizes the recommendation of 1.6 grams of ALA per day for the purposes of nutrient content claims. Therefore, one ounce of walnuts is an excellent source of alpha linolenic acid, providing 2.5 grams of ALA.

Q. Does heating (i.e toasting, boiling or frying) affect the nutrient content of walnuts?

A. The nutrient profile of walnuts changes insignificantly when roasted, toasted or baked for short periods of time.

Q. I am counting carbs. Where do walnuts fall for those on a low-carb diet?

A. Walnuts contain very little carbohydrate. One ounce of walnuts contains 4 grams carbohydrates and 2 grams fiber resulting in only 2 grams of net carbohydrates. 

Q. What are the major differences between black and English walnuts?

A. California Walnuts are English walnuts. Their scientific name is Juglans Regia. English walnuts are native to the Middle East. The black walnut is a Native American species. Currently the black walnut is used mainly as a rootstock for English walnuts. The meats are tasty but thanks to a very thick shell, they are a lot of work to crack and remove from the shell. Nutritionally speaking black walnuts contain approximately 10% less total fat and approximately 80% less omega-3 fatty acids (ALA) per serving than English walnuts. According to the most recent USDA Nutrient Database, SR 21, one ounce of black walnuts contains 16.7 grams of total fat and .57 grams of ALA. One ounce of English walnuts contains 18 grams of total fat and 2.5 grams of ALA.

Q. I am looking for weight equivalents for walnut pieces and halves.

A: According the USDA Database Standard Reference 21:

  • 1 walnut half = 2 grams
  • 1 ounce of walnuts = 14 halves
  • 1 cup walnut pieces = 120 grams
  • 1 cup walnuts, chopped = 120 grams
  • 1 cup shelled walnuts = 50 halves = 100 grams

Q. We finely chop walnuts and put them on our breakfast cereal. Is it okay to keep them in a container and use as needed? Will they spoil if not refrigerated? Do we lose any of the nutrition by chopping?

A. Walnuts are rich in polyunsaturated fat, which, when exposed to heat and air, does oxidize quickly, so if you chop them up it is best to store in an airtight container in the refrigerator or freezer to ensure freshness. Chopping does not affect the nutritional value as long as they are stored properly.

Q. I would like to eat more walnuts, but am concerned about weight gain!

A. Studies indicate that adding walnuts to a healthy diet may not lead to weight gain. A randomized, prospective trial, published in the International Journal of Obesity, evaluated weight loss patterns of 101 overweight men and women. During this 18-month study, subjects consumed either a moderate-fat Mediterranean diet including nuts such as walnuts (35 percent of energy) or a standard low-fat diet (20 percent of energy). The participants following a Mediterranean-style moderate fat weight loss diet, including peanuts and tree nuts, such as walnuts, were able to improve weight-loss and keep weight off for a longer period than people following the traditionally recommended low-fat diet. The researcher suggest that adding nuts may help satiety which is a factor in successful dieting. (Int J Obes Relat Metab Disord.2001 Oct;25(10):1503-11)

 Q: What's the best way to store walnuts?

 A: Keep shelled walnuts tightly sealed and store refrigerated for up to 6 months or in your freezer for up to one year. In-shell walnuts will remain fresh for several months when stored in a cool, dry place. Do not shell until ready to use. Take special care when storing walnuts with other foods as they sometimes can absorb odors of other foods, like citrus, fish etc

Have a question that is not in the list? Email info@walnuts.org for answers.