Berries & The Microbiome

A Berry Interesting Story  

Berries have been consumed for centuries across multiple continents. Interestingly, the word berry originates from an Old English word that actually means grape. While grapes are technically berries—each fruit comes from its own flower—the word “berries,” in modern day lexicon, usually refers to blueberries, raspberries, strawberries, and the like. Beyond simple consumption of these fruits, they also confer symbolic meaning. In European art, strawberries can represent goodness and holiness, or promiscuity, given all of the exteriorly strewn seeds. The rich red hue of strawberries represents love and passion. In indigenous Native American culture, blueberries are associated with divine origin, given the 5-point star on the bottom of each blueberry.  

Regardles of the symbolic meaning drawn from the common berry types, they are arguably some of the most popular fruits to eat due to their sweet and inviting flavors. These small delicious treats gifted to us by Mother Nature contain wondrous capability for positively improving our lives.  

Health Effects of Berries  

Beyond the wonderful flavors of berries, there is a plethora of literature espousing the amazing health benefits of these fruits. Blackberries exhibit a high amount of antioxidants called anthocyanins. The health benefits of anthocyanins include being brain-protective, cardiovascular protective, anti-inflammatory, and anti-diabetic. In animal models, blueberries also demonstrate wide-ranging health benefits including the improvement of kidney function largely through reduction of inflammatory stress. Beyond their positive cellular effects, berries also demonstrate the ability to modify expression of our genes. Strawberries, like blueberries, blackberries, and raspberries, contain antioxidant molecules called phenols that are not only able to change gene expression, but they are also able to protect our DNA.  

Berries Change the Microbiome  

The gut-modulating effects of berries are exerted through their fiber content and polyphenol antioxidant content. Fibers change the intestinal environment, acting as food substrate for bacteria to utilize in their growth. In one study of human volunteers, consumption of a wild blueberry drink for 30 days increased the abundance of Bifidobacterium in the intestinal tract when compared to placebo. Deficiency of bifidobacterium has been found in irritable bowel syndrome. Reduction in bifidobacterium is also associated with non-intestinal diseases such as asthma and obesity.  

In one animal model, strawberries were shown to positively affect the gut by increasing the abundance of beneficial bacteria bifidobacteria, and lactobacillus, while also decreasing the abundance of negative bacteria. Blackberries, blueberries, and strawberries have all been demonstrated in both animal and human models to alter the gut microbiota bacterial makeup.  

Berries in Gut Disease  

Berries have enormous antioxidant capacity when compared with other fruits. Given this, it is no wonder they are being studied as anti-inflammatories in health and disease. In one particular animal model, researchers intentionally created inflammation within the guts of mice to study the effects of raspberries. When these mice with inflamed large intestines were supplemented with red raspberries, researchers found that the colon structure was protected and there was overall less inflammatory chemicals in the intestines of the red raspberry supplemented mice. There also appeared to be an increase in proteins that protect the gut walls from what we call “leaky gut.”  

Colorectal cancer is a burgeoning issue in industrialized nations with a rising incidence occurring in younger populations. In an animal model of colorectal cancer, anthocyanin antioxidants found in freeze-dried black raspberry powder were found to alter the expression of genes associated with colorectal cancer. The anthocyanins found in freeze-dried black raspberry powder also positively modified the gut bacteria makeup. Numerous studies demonstrate the inverse relationship between fruit and vegetable consumption and subsequent development of cancer, including colon cancer.  

Increased intestinal permeability, also known as leaky gut, is associated with both intestinal and non-intestinal diseases. Gut barrier disruption is caused by a multitude of factors including foods, bacterial imbalance, medications, chemicals, and environment toxins. In a cell study, blueberry was demonstrated to block gut barrier dysfunction caused by an E.coli bacteria strain. In my clinical practice, I often perform stool studies where I see increased intestinal permeability accompanied with microscopic intestinal inflammation. In this population I will often employ the use of intestinal anti-inflammatories such as berries to reduce inflammation.  

Conclusion  

Berries are a wonderful way to positively modulate the gut through anti-inflammatory, prebiotic effects. Berries accomplish this not only because of their fiber content, but largely through their anti-oxidant phenol effects. A key characteristic of berries is their high antioxidant capacity. This article focuses on three common berries, however, other berries with positive gut-modulating effects include elderberries, cranberries, bilberries, maqui berry, acai berry, and more!  Persons following a low-fodmap diet may want to use caution with high berry content in the diet as they can be problematic. In this population, I usually recommend starting on the lower-end by adding in approximately one serving per day, which equals about one-half cup.  

Dr. Asia Muhammad, ND

Naturopathic Doctor

Dr. Muhammad, ND has committed her practice to honoring the power of lifestyle modification to achieve optimal health. She has a special interest in GI health, evidenced in her practice’s focus on gastroenterology, as well as mind-body medicine, and stress management. Dr. Muhammad provides her patients individualized attention and evidence-based naturopathic solutions, including food, movement, botanicals, supplementation, and hypnosis. When she’s not working, she likes to play the piano, dance, and explore new foods.

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