By Dr. Mercola
One of the basic tenets of optimal health is to eat real food. Nuts certainly fit into this category and, as a bonus, are a convenient, ready-to-eat snack that you can carry in a purse or backpack or stash in a desk drawer at work.
Two of my favorite nuts are macadamias and pecans, in large part because they’re high in healthy fats but relatively low in carbohydrates and protein, which most Americans consume in excess.
However, you really can’t go wrong when eating a variety of nuts, assuming you eat them in moderation. Walnuts are another top choice that have been making headlines due to their numerous beneficial effects on health.
Daily Walnuts May Improve Overall Diet Quality
Researchers from the Yale University Prevention Research Center and colleagues had more than 100 study participants add two ounces of walnuts to their diets daily.1
The participants ate the walnuts for six months then removed the daily walnuts for another six months. Half of each group also received counseling about healthy nutrition, including how to offset the additional calories consumed by eating walnuts.
Several interesting results were found from this one simple dietary change.
For starters, the participants, who were at increased risk of developing diabetes because they were either overweight or had elevated blood sugar or blood pressure levels, had improvements in blood vessel wall (epithelial) function, and lower levels of LDL (low-density lipoprotein) cholesterol.
Improvements were also seen in other heart variables, such as blood pressure and body fat, but similar improvements were also seen in the group excluding almonds, which means the walnuts may not have been responsible for the heart benefits.
What was remarkable, however, was a significant boost in diet quality among the participants eating walnuts. And despite the added walnuts, none of the participants gained weight. David L. Katz, founding director of the Yale University Prevention Research Center, told Forbes:2
“Our primary outcome was diet quality, and that differed significantly between walnuts-added and walnuts-excluded … The implication of that is that (a) walnuts displace less nutritious foods when added to the daily diet; and (b) the net effect is a significant improvement in overall diet quality.
… The take-away here is: eat walnuts routinely, improve your overall diet quality – and apparently, without risk of weight gain … That is because though high in calories, walnuts are very satiating. That high ratio of satiety-to-calories makes them helpful in appetite control.”
Eating Walnuts May Lower Your Risk of Heart-Related Death
Walnuts contain the amino acid l-arginine, which offers multiple vascular benefits to people with heart disease, or those who have increased risk for heart disease due to multiple cardiac risk factors.
Walnuts also contain the plant-based omega-3 fat alpha-linolenic acid (ALA), which is anti-inflammatory. Research shows that people who eat a diet high in ALA are less likely to have a fatal heart attack and have a nearly 50 percent lower risk of sudden cardiac death.3
Eating just four walnuts a day has been shown to significantly raise blood levels of heart-healthy ALA,4 and walnut consumption supports healthy cholesterol levels.
Separate research showed that eating just one ounce of walnuts a day may decrease cardiovascular risk,5 and among those at high cardiovascular risk, increased frequency of nut consumption significantly lowers the risk of death.6
Previous research by Katz and colleagues also revealed that eating about two ounces of walnuts daily improved endothelial function in overweight adults with visceral fat without leading to weight gain.7 Endothelial dysfunction (affecting the inner lining of blood vessels) is associated with cardiovascular events.
Walnuts Have the Highest Level of Antioxidants of All Nuts
Antioxidants are crucial to your health, as they are believed to help control how fast you age by reducing free radicals, which are at the heart of age-related deterioration.
Walnuts contain several unique and powerful antioxidants that are available in only a few commonly eaten foods. This includes the quinone juglone, the tannin tellimagrandin, and the flavonol morin.8
Walnuts contain antioxidants that are so powerful at free-radical scavenging that researchers called them "remarkable,"9 and research has shown that walnut polyphenols may help prevent chemically-induced liver damage.10
One study also found that consuming high-antioxidant foods like walnuts “can decrease the enhanced vulnerability to oxidative stress that occurs in aging,” “increase health span,” and also “enhance cognitive and motor function in aging.”11
In another study, researchers found that nuts, especially walnuts, have potent antioxidant powers. Walnut polyphenols had the best efficacy among the nuts tested and also the highest lipoprotein-bound antioxidant activity.
The researchers concluded:12
“Nuts are high in polyphenol antioxidants which by binding to lipoproteins would inhibit oxidative processes that lead to atherosclerosis in vivo. In human supplementation studies nuts have been shown to improve the lipid profile, increase endothelial function and reduce inflammation, all without causing weight gain.”
Lead researcher Professor Joseph Vinson, Ph.D., Department of Chemistry at The University of Scranton, continued, “A handful of walnuts has almost twice the antioxidant content as an equivalent amount of any other commonly consumed nut.”13
The outermost layer of a shelled walnut – the whitish, flaky (or sometimes waxy) part – has a bitter flavor, but resist the urge to remove it. It’s thought that up to 90 percent of the antioxidants in walnuts are found in the skin, making it one of the healthiest parts to consume.14
Walnuts May Fight Chronic Diseases Like Diabetes and Cancer
When you add real foods to your diet, you’re adding in a multitude of beneficial compounds, from healthy fats to antioxidants. As such, you’ll find they tend to benefit your health in multiple ways as well. This is certainly the case with walnuts. In addition to potentially boosting your heart health, the beneficial dietary fat in walnuts has been shown to benefit metabolic parameters in people with type 2 diabetes.
Overweight adults with type 2 diabetes who ate one-quarter cup of walnuts daily had significant reductions in fasting insulin levels compared to those who did not, and the benefit was achieved in the first three months.15
Walnuts may even help reduce not only the risk of prostate cancer, but breast cancer as well. In one study, mice that ate the human equivalent of 2.4 ounces of whole walnuts for 18 weeks had significantly smaller and slower-growing prostate tumors compared to the control group that consumed the same amount of fat but from other sources.
Overall, the whole walnut diet reduced prostate cancer growth by 30 to 40 percent. According to another study on mice, the human equivalent of just two handfuls of walnuts a day cut breast cancer risk in half and slowed tumor growth by 50 percent as well.16
Walnuts may even impact male fertility. Among men who consume a Western-style diet, adding 75 grams (a bit over one-half cup) of walnuts daily significantly improved sperm quality, including vitality, motility, and morphology.17
Weight Gain Typically Not an Issue
Several of the studies already featured noted that participants added walnuts to their diets daily but didn’t gain any weight as a result. Taking this a step further, walnuts may even help you to lose weight as long as you don’t overeat them.
In one review of 31 trials, those whose diets included extra nuts or nuts substituted for other foods lost about 1.4 extra pounds and half an inch from their waists.18 Eating walnuts is also associated with increased satiety after just three days.19 Research presented at the 6th International Congress on Vegetarian Nutrition also highlighted nuts’ role in helping to reduce your risk of obesity. As reported in the Epoch Times:20
“[Purdue University’s Professor of Foods and Nutrition Dr. Richard] Mattes claims that nuts can actually suppress both the appetite and the brain’s desire for food, which can lead people to overeat even when they’re full.
Plus they’re energy-packed, which can impact the way your body adjusts your intake of calories throughout the day. Mattes suggested that a 100-calorie serving of nuts in the morning could decrease your calorie consumption by as much as 75 calories later in the day. This could be due to the filling nature of nuts, but more research is needed on this particular point.”
Raw and Organic Nuts Are Best
You can't really go wrong when choosing nuts to eat, as long as you pay attention to quality (and by nuts I’m referring to tree nuts, not peanuts, which are technically legumes that I don’t recommend eating). Walnuts are highly perishable and their healthful fats easily damaged.
If you’re purchasing shelled walnuts in bulk, avoid those that appear shriveled or smell rancid, or that you cannot verify are fresh. Walnuts should be stored in an airtight container in your refrigerator or freezer, whether they are shelled or unshelled.
Phytic acid, which is found in the coatings of nuts and seeds, is an "anti-nutrient" responsible for leeching vital nutrients from your body. Soaking nuts will help to get rid of the phytic acid and enzyme inhibitors, which can interfere with the function of your own digestive and metabolic enzymes, in the nuts.
To make them more palatable you can use a dehydrator to improve the texture. Enzyme inhibitors in nuts (and seeds) help protect the nut as it grows, helping to decrease enzyme activity and prevent premature sprouting.
When nuts are soaked, the germination process begins, allowing the enzyme inhibitors to be deactivated, and increasing the nutrition of the nut significantly, as well as making them much easier to digest. One exception is with macadamia nuts (and other white nuts), which have only negligible amounts of enzyme inhibitors, so soaking is not as necessary. If you prefer to eat nuts and seeds roasted, do so yourself so you can control the roasting temperature and time.
Walnuts Should Be Eaten in Moderation
Most Americans consume three to five times more protein than they need, along with excessive starchy carbs and not enough healthy fats. Excess dietary protein can lead to elevated blood sugar, weight gain, kidney stress, leaching of bone minerals, and stimulation of cancer cells, and it’s easy to overdo it if you eat a few handfuls of high-protein nuts. A more ideal protein intake is likely around one-half gram of protein per pound of lean body mass, which for most is 40 to 70 grams a day.
This is why my favorite nuts are those that are lowest in protein and highest in fat, including macadamia nuts, pecans, and Brazil nuts. The following list shows the nutrition facts in grams per one ounce for your most common tree nuts (one ounce of nuts equates to just over 28 grams, or about a small handful):21 If you’re a fan of walnuts, you can see they fall into the mid-range as far as protein and carbs are concerned. So feel free to eat them, even daily if you like, but do so in moderation.
Numbers are grams per ounce