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“…decrease inflammation, boost memory, and support a healthy heart.”

Grapes have been recognized for their ability to decrease inflammation, boost memory, and support a healthy heart. New research dives deeper into explaining how these benefits can take effect due to the way in which your gut microbiome and metabolism are responding to them. So how do you prefer to consume your grapes? Whether it’s as a juice, a glass of wine, jam, frozen, or fresh, you can benefit from the health-promoting effects that grapes have to offer, albeit to varying degrees. Fresh, organically grown grapes are definitely the healthiest choice. Grape juice devoid of much of the fiber is associated with glucose and insulin spikes, which is also a problem with jams. And recent scientific evidence discourages wine consumption as a way to increase the intake of health promoting ingredients in wine, such as the polyphenols.

In a recent study, researchers selected a group of 41 healthy adult individuals and gave them three servings of grapes daily. The trial period took place over the course of a two-month period. Participants consumed a restricted diet for the first two-weeks of the study, limiting the intake of which foods they can have, while consuming three servings of grapes daily. During weeks three and four, they continued following the restricted diet, but now consumed the three servings of grapes in a freeze-dried powdered supplement form. For the last 30 days, participants stopped consuming grapes altogether to allow for the observation of the lasting effects that grape consumption may have on the gut microbiomes of the participants.

The research was led by Dr. John M. Pezzuto, Dean and Professor at the Western New England University College of Pharmacy and Health Sciences. Researchers collected plasma, urine, and stool samples from every participant on days 15, 30, and 60 of the study. Throughout the two-month period, researchers observed shifts in the bacteria within participants’ gut microbiomes, as well as changes in enzyme levels. They even found that some participants still showed changes in their gut microbiome even after stopping consumption of grapes for 30 days.

“Throughout the two-month period, researchers observed shifts in the bacteria within participants’ gut microbiomes, as well as changes in enzyme levels.”

Dr. John M. Pezutto said that the altered enzyme levels and changes to biological pathways caused by daily consumption of grapes may be affecting metabolites that are able to reach the organs. Nonetheless, the alteration of the gut bacteria and enzymes is very complex and further research will be needed to draw a clear conclusion.

Dr. Hana Kahleova, PhD, Director of Clinical Research at the Physicians Committee for Responsible Medicine, also commented on the process. She stated that the health benefits could be explained by the fibers of the grapes since they act as a prebiotic. The fibers found in grapes feed the good gut bacteria and then produces short-chain fatty acids, leading to these health benefits.

“..the health benefits could be explained by the fibers of the grapes since they act as a prebiotic.”

Dr. Kahleova said that the polyphenols found in grapes could also be responsible for the effect that a grape-enriched diet has on our health. Polyphenols have been shown to increase the relative prevalence of “good” gut bacteria species such as Bifidobacterium and Lactobacillus. Dr. Franck Carbonero, Assistant Professor at Washington University’s Elson S. Floyd College of Medicine, agreed that the polyphenols are likely responsible for the modulation of gut bacteria caused by consumption of the grapes.

“Polyphenols have been shown to increase good gut bacteria strains such as Bifidobacterium and Lactobacillus.”

While this study was able to highlight the positive health effects that grapes can have on modulating the gut microbiome, further research is needed. One major limitation is the short-term period in which the study took place and the small sample size of the study. Furthermore, the participants were all healthy adults with no underlying health conditions such as diabetes, cardiovascular disease, or other health problems.

Dr. Pezzuto addressed the study limitations and stated that the analyses are still ongoing. He said that the research team hopes to provide a clearer relationship between grapes and gut health in the future.

Despite more research being needed to better understand the effects of grapes on the gut and overall health, it is clear that grapes help to promote a healthy gut microbiome, and polyphenols contained in grapes are the most likely health promoting ingredients. Choosing foods that are gut friendly and promote healthy gut bacteria, such as grapes, will have significant benefits on overall health. After all, the gut microbiome plays a major role in both physical and mental health and having a healthy balance of good bacteria is key.