There are few foods that are as nutritiously complete and good for the human body as walnuts. For more than a dozen years, research by highly respected scientific and clinical experts has continued to reveal that this “Super Food” is packed with nutrients that positively affect the human body on a multitude of levels.
An ounce of walnuts has more antioxidants than the daily sum of what the average person gets from fruits and vegetables.
Walnuts contribute nutrients essential to a healthy lifestyle. Eating walnuts is one of the easiest things a person can do to improve their health.
Good for: Mood
Walnuts are packed with tryptophan; an amino acid your body needs to create the feel great chemical serotonin. (In fact, Spanish researchers found that walnut eaters have higher levels of this natural mood-regulator.) Another perk: "They're digested slowly," Dr. Katz says. "This contributes to mood stability and can help you tolerate stress."
While most varieties of nuts boast health benefits, the unique fat make-up of walnuts makes them particularly helpful when it comes to lowering cholesterol. Rich in polyunsaturated fats and the only nut source of plant-based omega-3 fatty acids, walnuts are a star food for cardiovascular health. Harvard researchers found that adding walnuts to the daily diet, even for the short term, creates dramatic drops in cholesterol. Study participants averaged a 10-point drop in total cholesterol and a nine-point drop in LDL, or the “bad” cholesterol.
Fact: Walnuts contain the highest concentration of antioxidants of any kind of nut, and studies have shown that eating them regularly can help reduce your chance of cardiovascular disease and protect against diabetes and certain cancers. They are also a great source of fiber, and they contain omega-3 fats, alpha-linolenic acid, and plant sterols that are known to help lower cholesterol levels. Walnuts are also a good source of zinc and folate that can help fight stress, increase your serotonin level, and boost brainpower. A 1-ounce serving of walnuts amounts to about 180 calories, and as a fun fact, California grows approximately 75% of the world’s walnut supply.
Fact: Walnuts are good sources of plant-based omega-3 fats, #natural phytosterols and antioxidants that are so powerful at free-radical scavenging that researchers called them "remarkable." Plus, walnuts may help reduce not only the risk of prostate cancer, but breast cancer as well. They’ve also been shown to reverse brain aging in rats and boost heart health in people with diabetes.
Walnuts: Wonder Food for Your Brain
With its two lobes that resemble a brain, the walnut perfectly advertises its brain-boosting benefits. Rich in omega-3 essential fatty acids, walnuts protect cardiovascular health, improve cognitive function, and possess anti-inflammatory benefits that are helpful for asthma, rheumatoid arthritis, and inflammatory skin diseases like eczema and psoriasis. The anti-inflammatory qualities are also thought to prevent obesity and help with weight maintenance—which may surprise you, given the high calorie and high fat content of walnuts. However, walnuts are full of high-quality fats and nutritious compounds, and as long as they are consumed in moderation, they will not negatively impact weight. Additionally, walnuts contain the antioxidant compound ellagic acid, which supports the immune system and is thought to have many anti-cancer properties. Want to know more? Check out walnuts in The Natural Health Dictionary.
Researchers are convinced—more than ever before—about the nutritional benefits of walnuts when consumed in whole form, including the skin. We now know that approximately 90% of the phenols in walnuts are found in the skin, including key phenolic acids, tannins, and flavonoids. Some websites will encourage you to remove the walnut skin—that whitish, sometimes waxy, sometimes flaky, outermost part of shelled walnuts. There can be slight bitterness to this skin, and that's often the reason that websites give for removing it. However, we encourage you not to remove this phenol-rich portion.
- The form of vitamin E found in walnuts is somewhat unusual, and particularly beneficial. Instead of having most of its vitamin E present in the alpha-tocopherol form, walnuts provide an unusually high level of vitamin E in the form of gamma-tocopherol. Particularly in studies on the cardiovascular health of men, this gamma-tocopherol form of vitamin E has been found to provide significant protection from heart problems.
- Most U.S. adults have yet to discover the benefits of walnuts. A recent study has determined that only 5.5% of all adults (ages 19-50) consume tree nuts of any kind! This small percentage of people actually do a pretty good job of integrating tree nuts (including walnuts) into their diet, and average about 1.25 ounces of tree nuts per day. But the other 94.5% of us report no consumption of tree nuts whatsoever. In a recent look at the nutritional differences between tree nut eaters and non-eaters, researchers have reported some pretty notable findings: on a daily average, tree nut eaters take in 5 grams more fiber, 260 milligrams more potassium, 73 more milligrams of calcium, 95 more milligrams of magnesium, 3.7 milligrams more vitamin E, and 157 milligrams less sodium!
- Many of us can go local for our supply of walnuts. According to the latest trade statistics,of all walnuts grown in the U.S.,the vast majority (almost 90%) come from California, and particularly from the San Joaquin and Sacramento Valleys. Buying walnuts closer to home can provide great benefits from the standpoint of sustainability.
- Phytonutrient research on the antioxidant and anti-inflammatory benefits of walnuts has moved this food further and further up the ladder of foods that are protective against metabolic syndrome, cardiovascular problems, and type 2 diabetes. Some phytonutrients found in walnuts— for example, the quinone juglone—are found in virtually no other commonly-eaten foods. Other phytonutrients—like the tannin tellimagrandin or the flavonol morin—are also rare and valuable as antioxidants and anti-inflammatory nutrients. These anti-inflammatory and antioxidant phytonutrients also help explain the decreased risk of certain cancers—including prostate cancer and breast cancer—in relationship to walnut consumption.
No aspect of walnuts has been better evaluated in the research than their benefits for the heart and circulatory system. Some review studies have emphasized the very favorable impact of walnuts on "vascular reactivity," namely, the ability of our blood vessels to respond to various stimuli in a healthy manner. In order to respond to different stimuli in a healthy way, many aspects of our cardiovascular system must be functioning optimally. These aspects include: ample presence of antioxidant and antiinflammatory nutrients, proper blood composition, correct balance in inflammation-regulating molecules, and proper composition and flexibility in our blood vessel walls. Researchers have determined the ability of walnuts to have a favorable impact on all of these aspects. The chart below summarizes some key research findings about walnuts and heart health:
|Cardiovascular Aspect||Walnut Benefit|
|Blood Quality||decreased LDL cholesterol; decreased total cholesterol; increased gammatocopherol; increased omega-3 fatty acids in red blood cells (alpha-linolenic acid)|
|Vasomotor Tone||decreased aortic endothelin; improved endothelial cell function|
|Risk of Excessive Clotting||decreased maximum platelet aggregation rate; decreased platelet activation|
|Risk of Excessive Inflammation||decreased C reactive protein (CRP); decreased tumor necrosis factor alpha (TNF-a)|
Walnuts Help Reduce Problems in Metabolic Syndrome
In the United States, as many as 1 in 4 adults may be eligible for diagnosis with Metabolic Syndrome (MetS). MetS isn't so much a "disease" as a constellation of problematic and overlapping metabolic problems including excessive blood fats (triglycerides), high blood pressure, inadequate HDL cholesterol, and obesity (as measured by waist circumference, and/or body mass index). Recent studies have shown that approximately one ounce of walnuts daily over a period of 2-3 months can help reduce several of these MetS-related problems. In addition, addition of walnuts to participant diets has also been shown to decrease "abdominal adiposity"—the technical term for the depositing of fat around the mid-section. Importantly, the MetS benefits of added walnuts have been achieved without causing weight gain in any the studies we've seen to date.
Benefits in Treatment of Type 2 Diabetes
Although we think about type 2 diabetes as a problem primarily related to blood sugar control and insulin metabolism, persons diagnosed with type 2 diabetes typically have health problems in other related systems, and are at special risk for cardiovascular problems. An important part of the goal in designing a diet plan for persons with type 2 diabetes is lowering the risk of future cardiovascular problems. In this context, consumption of walnuts is establishing a more and more impressive research track record. Increased flexibility in the response of the cardiovascular system following meals has been a repeated finding in research on walnuts. A variety of different measurements on blood vessel functioning (including their measurement by ultrasound) show a relatively small amount of daily walnut intake (1-2 ounces) to provide significant benefits in this area for persons with type 2 diabetes. Better blood fat composition (including less LDL cholesterol and less total cholesterol) has also been demonstrated in persons with type 2 diabetes.
Given the wide variety antioxidant and anti-inflammatory nutrients found in walnuts, it's not surprising to see research on this tree nut showing measurable anti-cancer benefits. The antioxidant properties of walnuts help lower risk of chronic oxidative stress, and the anti-inflammatory properties help lower risk of chronic inflammation, and it is precisely these two types of risk, that, when combined, pose the greatest threat for cancer development. Prostate cancer and breast cancer are the best-studied types of cancer with respect to walnut intake, and their risk has been found to be reduced by fairly large amounts of walnut consumption. (Large in this case means approximately 3 ounces per day.) For prostate cancer, the evidence is somewhat stronger, and more studies have involved human subjects. For breast cancer, most of the evidence has been based on studies of rats and mice.
Lower Blood Pressure
Thanks to the high levels of omega-3 fatty acids they contain, walnuts are very beneficial to all aspects of the cardiovascular system. Research has found that just a few walnuts per day may help to reduce blood pressure.
Walnuts contain omega-3 fatty acids, which have been found to effectively lower cholesterol levels. People with high cholesterol can significantly lower their levels by eating walnuts and other foods that are high in fiber and essential fatty acids.
Research has found walnuts to be promising in the fight against cancer. Studies on human subjects found that a few walnuts per day significantly reduced the risk of prostate cancer, while animal studies have found similar results on the risk of breast cancer.
The omega-3 fatty acids in walnuts are great for the brain. Eating walnuts as well as other foods high in omega-3s such as seafood and flaxseed can maintain and improve memory and overall cognitive function.
Because walnuts are rich in fiber, they are a great way to keep your digestive system healthy. Getting enough fiber on a daily basis is essential to keeping your bowels functioning correctly. Most sources of protein, such as meat and dairy, are lacking in fiber. So, you can get both the protein benefits and fiber benefits at the same time by eating walnuts.
The selenium, zinc, biotin and essential fatty acids in walnuts help to promote healthy, shiny, strong hair.
Recent studies have shown that eating nuts on a daily basis can help to prevent gallstones. Add walnuts to your cereal or snack on a few between meals to prevent gallbladder disease.
Walnuts contain bio-available melatonin, which has been found to improve sleeping patterns. Adding a few walnuts into your daily meal plan may help you to rest better at night.
One of the essential fatty acids in walnuts is called alpha linolenic acid, and this compound has been associated with stronger, healthier bones. When you are getting omega-3 fatty acids on a regular basis, inflammation will decrease, and lower levels of inflammation are related to stronger bones.
Even though walnuts are high in calories and contain fat, they can actually help you to lose weight or maintain a healthy weight. The fiber, protein, vitamins and minerals can boost your health and help you to avoid eating too many other foods that are high in calories but low in nutrition.
Other Health Benefits
The anti-inflammatory nutrients in walnuts may play a special role in support of bone health. A recent study has shown that large amounts of walnuts decrease blood levels of N-telopeptides of type 1 collagen (NTx). These collagen components provide a good indicator of bone turnover, and their decreased blood level in response to walnut intake is an indication of better bone stability and less mineral loss from the bone. "Large amounts" of walnuts (in this study, actually raw walnuts plus walnut oil) translated into 50% of total dietary fat. In an everyday diet that provided 2,000 calories and 30% of those calories from fat, this 50% standard for walnuts would mean about 67 grams of fat from walnuts or 4 ounces of this tree nut on a daily basis. While this amount is more than most people would ordinarily consume, we expect the health benefits of walnuts for bone health to be demonstrated in future studies at substantially lower levels of intake.
Walnuts have also produced a good track record in the research as a desirable food for support of weight loss and for prevention of obesity. That finding often surprises people because they think of high-fat, high-calorie foods as a primary contributing factor to obesity and to weight gain. In general, overconsumption of high-fat, high-calorie foods is a primary contributing factor to obesity and weight gain. However, obesity has also been clearly identified by researchers as involving chronic, unwanted inflammation. As discussed earlier in this Health Benefits section and throughout this walnuts' profile, walnuts are unique in their collection of anti-inflammatory nutrients. These nutrients include omega-3 fatty acids; phytonutrients including tannins, phenolic acids, and flavonoids; quinones like juglone; and other anti-inflammatory phytonutrients. These anti-inflammatory benefits can overshadow the high
calorie and high-fat risk posed by walnuts, and that's exactly what they have done in an increasing number of research studies involving risk and/or treatment of obesity. While it is definitely possible to overconsume walnuts, most everyday diets could remain correctly balanced in terms of calories and fat while still including fairly generous amounts of walnuts (in the range of 1-3 ounces).
A limited (but increasing) number of studies have shown potential health benefits for walnuts in the area of memory and general thought processes (often referred to as "cognitive" processes). Thus far, most of the initial research in this area has involved rats and mice, but we expect to see cognitive benefits of walnuts for humans becoming a topic of increasing research interest.
A final fascinating aspect of walnuts and their potential health benefits involves melatonin (MLT). MLT is a widely-active messaging molecule in our nervous system, and very hormone-like in its regulatory properties. MLT is critical in the regulation of sleep, daily (circadian) rhythms, light-dark adjustment, and other processes. It has also been found to be naturally occurring within walnuts. Average melatonin (MLT) content of walnuts is approximately 3.6 nanograms (ng) per gram (g), or 102ng/ounce. Other commonly eaten foods—for example, cherries—have also been found to measurable amounts of MLT. Researchers are not yet sure how everyday intake of MLT from walnuts is involved in our health, but several study authors have hypothesized about the MLT in walnuts as playing an important role (along with other walnut nutrients) in the anti-cancer benefits of this unusual food.
While walnut trees have been cultivated for thousands of years, the different types have varying origins. The English walnut originated in India and the regions surrounding the Caspian Sea, hence it is known as the Persian walnut. In the 4th century AD, the ancient Romans introduced the walnut into many European countries where it has been grown since. Throughout its history, the walnut tree has been highly revered; not only does it have a life span that is several times that of humans, but its uses include food, medicine, shelter, dye and lamp oil. It is thought that the walnuts grown in North America gained the moniker "English walnuts," since they were introduced into America via English merchant ships.
Within the U.S., about 90% of all walnuts are grown in California, particularly within the San Joaquin and Sacramento Valleys.