Walnuts (Juglans regia) are the edible seed of the walnut tree. Walnuts are technically the seed of a stone fruit and are not a true nut. Walnuts originated in Iran, and have been known and consumed for at least 10,000 years. The Romans spread the walnut across Northern Africa and Europe. The part of the walnut generally consumed is called the kernel. China is the world’s leading producer of walnuts, producing 55% of the world’s total with 2.5 million metric tons per year. The United States is the world’s leading exporter, producing 33% of the world’s exports with 120,000 metric tons.
Walnuts reached the United States in the 1700s from England. In the US walnuts were often referred to as English walnuts despite walnuts never being commercially grown at a large scale in England. Most US commercial walnuts are grown in California. Walnuts first reached California in the mid 1700s, with commercial production beginning in the late 19th century. While the only commercially grown walnut variety is Juglans regia, technically any member of the Juglans genus is a walnut. Black walnuts (Juglans nigra) are native to the US, but are not grown commercially due to the difficulty of de-shelling them.
One 1 oz serving of walnuts contains 180 calories. They an excellent source of copper and manganese and a good source of magnesium. Walnuts are high in fat, particularly polyunsaturated fat, as well as protein.
Walnuts contain 4 grams of carbohydrates per serving. They are not a significant source of sugar, containing only 1 gram per serving. Walnuts have a glycemic index of 15, making them a low glycemic food.
Walnuts contain 2 grams of fiber per serving. The fiber in walnuts is approximately 30% soluble fiber and 70% insoluble fiber. Insoluble fiber can be helpful in preventing constipation and promotes regular bowel movements. Soluble fiber also aids in healthy bowel movements, can lower cholesterol, and helps diabetics maintain blood glucose levels.
Walnuts contain 4 g of protein per serving. While they are a good source of protein, walnuts contain limiting amounts of the essential amino acids lysine and methionine.
Walnuts contain 18 g of fat per serving. Approximately 90% of the fat in walnuts is unsaturated fat. The major fatty acid contained in walnuts is linoleic acid, which accounts for approximately 55% of the fat content of walnuts (1). Oleic acid and linolenic acid are present at approximately 25% and 10% respectively (1). Walnuts are unique amongst nuts in that they contain large amounts of polyunsaturated fatty acids.
Vitamins & Minerals
Walnuts are an excellent source of copper (50% of the FDA recommended daily value) and manganese (42% of the FDA recommended daily value). They are also a good source of magnesium, containing 11% of the FDA recommended daily value. Copper contributes to immune system function and helps prevent oxidative stress. Manganese helps with bone maintenance. Magnesium helps reduce feelings of tiredness and fatigue.
Walnuts have the highest antioxidant content of any nut (2). The antioxidant capacity of walnuts is higher than that found in a glass of red wine, a cup of apple juice, or a bar of chocolate (3). The most notable antioxidant classes in walnuts are phenolic compounds especially tannins, as well as tocopherols and melatonin (4). While some of these antioxidants are present in the walnut kernel, the majority are found in the thin, dark colored skin surrounding the walnut kernel (5). This skin is sometimes removed to better preserve walnuts, as it oxidizes more quickly than the walnut kernel. Tannins can help reduce blood pressure and improve blood lipid composition. Tocopherols help prevent oxidative stress in the body.
Increased nut consumption has been linked to a reduction in cardiovascular disease (6). Additionally, risk factors for developing cardiovascular disease including high blood pressure and poor lipid profiles improve with nut consumption (7). While most nuts contain predominately monounsaturated fatty acids, walnuts contain high amounts of polyunsaturated fatty acids. This unique fatty acid profile is thought to be responsible for the cholesterol lowering effect of walnuts (8). Consuming walnuts in intervention studies led to significant decreases in low density lipoprotein (LDL) or “bad” cholesterol (9). Inflammatory markers related to cardiovascular disease decreased with walnut consumption (9). Lipid profiles of walnut consumers improved compared to individuals who did not consume walnuts (9).
Benefits for Brain Health, Cognition, and Mental Health
Adults who consumed walnuts had better cognitive function and improved memory compared to those who did not consume nuts (10). Elderly women who were longtime consumers of walnuts had better cognitive function than those who did not eat nuts (11). The cognitive difference between women who ate five or more servings of walnuts per week versus those who did not consume nuts was 2 years (11). A study which gave individuals walnuts for 8 weeks showed that they had improved verbal reasoning after the study compared to before the study (12). Walnut consumption is associated with decreased depressive symptoms (13). In addition to less depressive symptoms, individuals who regularly consumed walnuts had less hopelessness, more interest in activities, and more energy (13).
Use in Traditional Medicine
Walnuts have been used in traditional medicine in both China and Europe. They have been used to treat coughs and stomach ailments (5). Walnuts have also been used to treat diarrhea and parasitic worms (14).
Walnut allergy is fairly common, affecting approximately 0.5% of individuals. Allergy severity can range from mild itching or discomfort to fatal reactions. For mildly allergic individuals, cooking walnuts generally destroys the allergenic compounds. Highly allergic individuals should practice complete avoidance.
Aflatoxin contamination of walnuts is also a concern. Aflatoxin is produced by mold which can grow on walnuts. Walnuts are fairly susceptible to mold growth if their shell and outer skin are removed. High moisture and high temperature storage are risk factors for aflatoxin production. Aflatoxin is a carcinogen and is poisonous. Moldy walnuts should never be consumed due to risk of aflatoxin exposure.
The following nutrition information is provided by the USDA for one ounce (28g) or about seven whole English walnuts or 14 halves.
At 4g of carbohydrates per serving, roughly 1g of sugar and a glycemic index of 15, walnuts are ok to eat on the Candida Diet.
However, make sure they are fresh and not moldy. Any mold and aflatoxin exposure will further complicate your Candida treatment plan by introducing another set of problems. This applies to anyone, Candida yeast infected or not.
If you have any questions about walnuts and the Candida Diet or any other questions about yeast infections, please feel free to contact us from the contact page of this website or talk to your doctor.
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