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Are Walnuts Good For You? Health Benefits and Side Effects

Under: Food & Diet, General Health

Looking for a simple yet tasty way to get more nutrients into your diet? Then look no further than walnuts, the single-serve vitamin and mineral powerhouse that has (rightfully) earned the moniker “mother of all nuts.” In this article, we crack open the facts about walnuts and look at their health benefits, side effects, and some easy ways to incorporate this wonder nut into your daily diet.

What are walnuts?

With their hard shell and unmistakable brain-like inner fruit, walnuts are actually the edible seeds from trees of the Juglans genus. They are the most widely-consumed nut globally. And their sweet taste and crunchy texture make them ideal additions to both sweet and savory dishes, including breads, cakes, salads, and vegetarian sauces.

Nutrition facts

All nuts are incredibly healthy but walnuts definitely take the cake with their impressive nutritional profile. According to the USDA, 1 cup of shelled walnuts (about 100 grams) contains:


  • Calories: 654
  • Protein: 15.2 grams
  • Carbs: 13.7 grams
  • Sugar: 2.62 grams
  • Fiber: 6.7 grams
  • Fat: 65.2 grams

Vitamins & Minerals

  • Copper
  • Manganese
  • Folic acid
  • Phosphorus
  • Iron
  • Vitamin B6
  • Vitamin E
  • Vitamin C

History & Health Benefits of Walnuts

To say that walnuts have been around for a while would be a bit of an understatement. Experts have found evidence that humans were already eating walnuts since prehistoric times. In fact, in an archeological dig in Southern France, scientists found fragments of roasted walnut shells in what seemed like a communal fire pit dating back to the Neolithic era, some 9,000 years ago.

The earliest written account that mentions walnuts dates back to 2,000 B.C. and comes from the ancient city of Babylon, where walnuts were reserved for Persian royalty only. In ancient Rome, walnuts, and the oil extracted from them, were considered “food for the gods” because of their many health benefits. And in medieval times, walnuts were touted as a remedy for headaches, mental illness, and seizures.

Today, the medicinal value of walnuts is well established. It could be due to their high antioxidant activity or perhaps thanks to their abundance of healthy fats. Still, these wrinkly nuts have been linked to several health benefits, including improved brain function, heart health, and decreased inflammation. Here are 5 proven health benefits of walnuts.

Walnuts are rich in healthy plant compounds

Each time you eat walnuts, you’re consuming a rich diversity of plant compounds proven to support health on many different levels. In fact, walnuts are among the richest dietary sources of antioxidants, ranking above virtually every other nut, including almonds, pecans, pistachios, and Brazil nuts.

Some noteworthy plant compounds in walnuts include:

  • Melatonin
  • Ellagic acid
  • Alkaloids
  • Flavonoids
  • Tannins

Walnuts are also an excellent source of alpha-linolenic acid, a type of omega 3 fatty acid found in plants. What’s more, a single serving of walnuts per day is enough to meet the recommendation for omega 3 fatty acids for both men and women, which is 1.6 and 1.1 grams, respectively.

Walnuts promote gut health

The human gut is made up of colonies of trillions of bacteria, which help balance not only your digestive tract but your overall health. However, an unhealthy balance of bacteria causes bacterial dysbiosis (reduced microbial diversity), a contributing factor to chronic diseases such as diabetes, cancer, and even heart disease.

But eating walnuts could be a good way of keeping your bacterial colonies in check, according to a 2018 study published in Nutrients. The analysis showed that participants who consumed 1.5 ounces of walnuts daily increased their bacterial diversity relative to when they didn’t eat walnuts. And in a recent study conducted by Penn State researchers, those who ate walnuts increased the number of a particular strain of gut bacteria beneficial for heart health.

Walnuts offer protection against certain kinds of cancer

Building on previous studies about gastrointestinal health, researchers found that some of the polyphenols found in walnuts are metabolized by gut bacteria and converted into urolithins, a type of compound that could help slow down the proliferation of cancer cells.

Walnuts are also chocked-full of bioactive components with anticancer properties, including omega 3 fatty acids, gamma-tocopherol, phytosterols, and polyphenols. In fact, in animal studies, walnuts were capable of suppressing cancer growth in breast and prostate tissues.

Interestingly, there’s also some evidence that eating nuts may be associated with a higher survival rate among breast cancer survivors, according to a study by Vanderbilt University Researchers. The study didn’t differentiate between different types of nuts, but walnut’s impressive nutritional composition sure makes them an ideal addition to any cancer-fighting diet.

Eating walnuts may improve brain function

Research suggests that walnuts may boost brain function and improve memory and focus.

As mentioned earlier, walnuts are a good source of omega 3 fatty acids, a polyunsaturated fat essential for cognitive function and brain development. So when researchers fed mice with Alzheimer’s walnuts every day for 10 months, both their memory and learning skills significantly improved.

Human studies have yielded promising results, as well. For example, an analysis that followed 64 healthy college students found that eating walnuts sharpened their reasoning skills, although there weren’t any improvements in their mood or memory. And one study looking at the protective effects on the brains of older adults found that eating walnuts was linked to better memory and increased neurogenesis.

Walnuts could help reduce blood pressure and boost heart health

Turns out that eating a handful of walnuts every day may be just what you need to keep your blood pressure under control. That is, according to a study published in the Journal of the American Heart Association in 2019.

For the study, 45 participants who were either obese or overweight were assigned into one of three different diet groups: a diet that included walnuts, a diet that didn’t include walnuts but incorporated the same amount of alpha-linolenic acid (ALA) from other sources, and a diet that substituted walnuts and ALA with another type of fatty acid.

At the end of the study, those who ate whole walnuts saw the most benefits, even when compared to volunteers who ate a diet with a similar nutrient profile (rich in ALA) but without consuming the actual nut. All in all, the walnut diet significantly reduced blood pressure and lowered cholesterol levels, both important markets for preventing heart disease.

Walnuts can be life-extending

A study published on 4/4/21 in the journal Nutrients found that a few handfuls of walnuts a week can help you live longer. The research, out of the Harvard T.H. Chan School of Public Health, found that eating five or more servings of walnuts per week helped people extend their life 1.3 years longer than people who didn’t eat walnuts (1 serving = 1 oz).

Five servings of walnuts per week were also associated with a 14 percent decreased risk of death, from any cause, and a 25 percent lower risk of dying from cardiovascular disease specifically.

Allergies and side effects

Walnuts are generally safe to eat and well-tolerated by most people, although folks with nut allergies should refrain from eating them to avoid adverse reactions. Avoid eating too many walnuts in one sitting if you have IBS, since they may soften your stool and cause diarrhea when eaten in large quantities.

Despite being high in calories, walnuts are not associated with weight gain. On the contrary, since they’re packed with fiber, many people find that eating walnuts as a snack makes them eat less because they feel full for longer. If you’re worried about gaining weight, though, you might want to consider lowering your fat intake on the days you consume walnuts.

All small nuts, including walnuts, carry the risk of choking in children. Never leave grown kids alone while eating walnuts, and avoid giving them to children younger than 7 years of age.

A final word

Walnuts can be a great addition to any diet. They have more omega 3 fatty acids than any other nut and boast an impressive antioxidant profile.  Among its many health benefits, walnuts could help reduce blood pressure, boost memory and thinking, and help diversity your gut microbiome. Don’t eat walnuts if you’re allergic to nuts, and talk to your doctor before adding walnuts to your diet if you have gut issues, like IBS or Crohn’s disease.


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