Walnuts have a storied history. They originated in ancient Persia, where they were reserved exclusively for royalty to consume. And in ancient Rome, they were labeled “Jupiter’s royal acorn,” marking them as the food of the gods.
Considering their nutritional value, there’s good reason to hold them in such high regard…
Over the years we’ve learned that eating walnuts can slash the risk of heart and blood sugar problems, cut the risk of metabolic syndrome, protect against free radical damage and promote living healthier longer.
But some of the most interesting research on the mechanism behind their benefits has to do with a special relationship between this treasured nut and your gut…
The impact of walnuts on your gut
Previous research has shown that walnuts are great for the gut because they have a probiotic effect.
“Research has shown that walnuts may have heart-healthy benefits like lowering cholesterol levels and blood pressure,” says Mansi Chandra, an undergraduate researcher at Juniata College in Huntingdon, Pa. “This motivated us to look at how walnuts benefited the gut microbiome and whether those effects led to the potential beneficial effects.”
To determine this, the researchers needed to study the gene expression of gut microbes using samples from a previous controlled-feeding study. That study put participants with high cardiovascular risk on a two-week standard Western diet, then randomly assigned them to one of three diets for six weeks with a break between each.
The first of the three diets incorporated whole walnuts. The other two diets included the same amounts of certain nutrients found in walnuts, but not the nuts: the second diet included omega-3 fatty acid alpha-linolenic acid (ALA) and polyunsaturated fatty acids; the third diet partially substituted another fatty acid known as oleic acid for the same amount of ALA found in walnuts.
Shortly before participants finished their diets, fecal samples were collected to analyze gene expression and the bacteria in the gastrointestinal tract. And this is where the researchers saw the gut’s contribution to the walnut’s biggest benefit…
According to the analysis, participants on the walnut diet saw their gut microbiome altered in a way that increased the body’s production of the amino acid L-homoarginine. Homoarginine deficiency has been linked to higher risk of heart problems.
“Our findings represent a new mechanism through which walnuts may lower cardiovascular disease risk,” Chandra says.
Walnuts: Whole food health benefits
This study is supportive of the fact that eating a whole food, as opposed to picking and choosing specific nutrients, may be key to grabbing all the benefits.
The participants who received some of the same nutrients found in walnuts, but did not consume the nut, didn’t benefit the way the walnut eaters did. That should be plenty of incentive to start adding them to your diet regularly.
How many walnuts should you eat daily? Most experts say one ounce of walnuts should do it. That’s equal to roughly a quarter cup, or one handful. They make the perfect replacement snack for those greasy chips and sugary treats.
Have you found walnuts don’t always sit well with you? Try this tip: Soak walnut kernels (that’s the meaty part removed from the shell) overnight first. By soaking them, you lower their level of phytic acid and make them easier to digest. Also, soaking promotes better metabolism and nutrient absorption.
Sources:
The heart benefits of walnuts likely come from the gut — EurekAlert!
History — California Walnuts
Walnuts: A worthy addition to your daily diet? — Harvard Health Publishing
How Many Walnuts Should You Eat in a Day? — Healthier Steps