Walnuts have higher antioxidant activity than any other common nut .
This activity comes from vitamin E, melatonin and plant compounds called polyphenols, which are particularly high in the papery skin of walnuts .A preliminary, small study in healthy adults showed that eating a walnut-rich meal prevented oxidative damage of “bad” LDL cholesterol after eating, whereas a refined-fat meal didn’t .
That’s beneficial because oxidized LDL is prone to build up in your arteries, causing atherosclerosis.
Walnuts are significantly higher in omega-3 fat than any other nut, providing 2.5 grams per 1-ounce (28-gram) serving .
Omega-3 fat from plants, including walnuts, is called alpha-linolenic acid (ALA). It’s an essential fat, meaning you have to get it from your diet.
According to the Institute of Medicine, adequate intake of ALA is 1.6 and 1.1. grams per day for men and women respectively. A single serving of walnuts meets that guideline
Observational studies have shown that each gram of ALA you eat per day lowers your risk of dying from heart disease by 10%
Test-tube, animal and human observational studies suggest that eating walnuts may reduce your risk of certain cancers, including breast, prostate and colorectal cancers
As noted earlier, walnuts are rich in the polyphenol ellagitannins. Certain gut microbes can convert these to compounds called urolithins .
Urolithins can have anti-inflammatory properties in your gut, which may be one way that eating walnuts helps protect against colorectal cancer. Urolithins’ anti-inflammatory actions could also help protect against other cancers .
What’s more, urolithins have hormone-like properties that enable them to block hormone receptors in your body. This may help reduce your risk of hormone-related cancers, specifically breast and prostate cancers .
More human studies are needed to confirm the effects of eating walnuts on decreasing the risk of these and other cancers, as well as to clarify all the ways or mechanisms by which they may help.
Walnuts are calorie dense, but studies suggest that the energy absorbed from them is 21% lower than would be expected based on their nutrients
What’s more, eating walnuts may even help control your appetite.
In a well-controlled study in 10 obese people, drinking a smoothie made with about 1.75 ounces (48 grams) of walnuts once a day for five days decreased appetite and hunger, compared to a placebo drink equal in calories and nutrients
Additionally, after five days of consuming the walnut smoothies, brain scans showed that the participants had increased activation in a region of the brain that helped them resist highly tempting food cues, such as cake and French fries.
Even though larger and longer-term studies are needed, this provides some initial insight as to how walnuts may help control appetite and weight.