Ask the Gut Why Walnuts are Heart-Healthy

They conducted their study by analyzing the genetic expression of microbes in participants who either consumed or did not consume a diet with walnuts.

That is according to research presented today at DiscoverBMB – the annual meeting of the American Society for Biochemistry and Molecular Biology.

The study, which was funded by the California Walnut Commission, hasn’t been published yet in a peer-reviewed journal.


The researchers used metatranscriptomics, which is the study of gene expressions in gut microbes, to monitor changes that might occur when someone alters their diet. The scientists specifically looked at how heart health could be affected.

The findings of the study suggested that eating walnuts could alter the gut microbiome by increasing the body’s production of the amino acid L-homoarginine. As a consequence, this might lower the risk of developing heart disease.

The Three Types of Study Diets

The researchers used samples from a previously performed controlled-feeding study. The study included 35 participants with a high risk of cardiovascular disease.

Participants were put on a two-week standard Western diet and then were randomly assigned to one of three study diets:

  • A diet consisting of whole walnuts.
  • A diet that had the same quantity of omega-3 fatty acids and polyunsaturated fatty acids as the walnut diet but did not include walnuts.
  • A diet that partially substituted the fatty acid, oleic acid, for the same amount that would be derived from walnuts, but the diet did not include walnuts.

The participants followed each diet for six weeks, with a break in between.

The Role of Gut Bacteria Behind Why Walnuts are Heart-Friendly

The diets were developed to demonstrate how walnuts affect cardiovascular health due to bioactive components, alpha-linolenic acid, or ALA content, or whether walnut ALA can replace dietary saturated fats.

Shortly before the participants completed a diet, their fecal samples were collected.

Interestingly, those who were on a diet of whole walnuts had higher levels of Gordonibacter bacteria in their gut – metabolites that exert anti-inflammatory activity and gene expressions for the increase of the body’s production of the amino acid L-homoarginine.

The researchers concluded that changes to the gut microbiome caused beneficial pathways that could reduce cardiovascular risk factors. However, they noted that further research is needed to confirm their observations.

This study suggests that walnuts might promote positive changes in the gut microbiome and promote gut-friendly bacteria that can help the body absorb and use certain antioxidants linked to reduced heart disease risk.

Why Should you Include Walnuts in your Diet

Previous research says that walnuts are a healthy addition to diets. They contain omega-3 fats and antioxidants and are high in fiber. A one-ounce serving of walnuts has about seven whole walnuts. However, the study used a diet with about 28 walnuts per day.

A one-ounce serving of walnuts contains about 185 calories and 4.3 grams of protein, 3.9 grams of carbohydrates, 0.74 grams of sugar, 1.9 grams of fiber, and 18.5 grams of fat.

Even though walnuts are pretty high in calories and fat, a study reported that walnuts do not significantly increase the risk of obesity or weight gain (1 Trusted Source
Does regular walnut consumption lead to weight gain?

Go to source).

Walnuts are rich in fiber and omega-3 fatty acids – two nutrients that have a positive influence on cardiovascular disease risk. Fiber has been associated with decreasing cholesterol, and omega-3 fatty acids are linked to many disease processes that reduce inflammation.

Other foods like chia seeds, pumpkin seeds, and flax seeds offer similar amounts of omega-3 fatty acids

Although this is not the first study to showcase that walnuts are a beneficial addition to diets, it is the first that explained how that works due to improved gut microbiome.

Many studies in the past have shown a link between walnut consumption and reduced heart disease risk, which might provide one possible mechanism for the benefits. Research on the gut microbiota is in its initial stages, but over the years, it has become clear that the role of bacteria living in the gut and throughout the body plays a vital role in regulating many aspects of our health, including heart disease risk.

References :

  1. Does regular walnut consumption lead to weight gain? – (

Source: Medindia

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