Their research, published in the Royal Society of Chemistry's journal Food and Function, examined how polyphenol oxidase (PPO) -- an enzyme found naturally in many fruits and vegetables -- affects the body's ability to take in flavanols. These bioactive compounds are linked to improved heart and brain health and are abundant in foods like apples, pears, blueberries, blackberries, grapes, and cocoa (all popular smoothie ingredients).

Lead author Javier Ottaviani, director of the Core Laboratory of Mars Edge, part of Mars, Inc., and adjunct researcher at UC Davis, explained: "We sought to understand, on a very practical level, how a common food and food preparation like a banana-based smoothie could affect the availability of flavanols to be absorbed after intake."

Anyone who has sliced an apple or peeled a banana has seen the fruit quickly turn brown. That browning occurs when PPO reacts with oxygen after the fruit is cut or bruised. The UC Davis team wanted to know if that same enzyme activity affects how much of these beneficial flavanols the body absorbs when fruits are blended together in smoothies.

Bananas vs. Berries: The Smoothie Showdown

To test this, participants consumed two different smoothies -- one made with banana, which has high PPO activity, and another made with mixed berries, which have low PPO activity. They also took a flavanol capsule for comparison. Afterward, researchers measured flavanol levels in blood and urine samples.

The results were striking. People who drank the banana smoothie had 84% lower flavanol levels compared to those who took the control capsule.

"We were really surprised to see how quickly adding a single banana decreased the level of flavanols in the smoothie and the levels of flavanol absorbed in the body," Ottaviani said. "This highlights how food preparation and combinations can affect the absorption of dietary compounds in foods."

What Are Flavanols?

Flavanols are natural compounds found in foods like cocoa, berries, apples, and grapes. They're part of a larger group of plant nutrients called polyphenols and are known for supporting heart and brain health. Research suggests that flavanols can help improve blood flow, support memory, and reduce inflammation when consumed regularly.

Choosing the Right Fruit Pairings

In 2022, the Academy of Nutrition and Dietetics recommended consuming 400 to 600 milligrams of flavanols each day for cardiometabolic health. Ottaviani noted that for people aiming to reach that target, it helps to pair flavanol-rich fruits such as berries with ingredients that have low PPO activity, like pineapple, oranges, mango, or yogurt.

Bananas are still a nutritious fruit, but Ottaviani advised that if you enjoy banana smoothies, it may be best not to mix them with flavanol-heavy foods like berries, grapes, or cocoa. The same principle applies to other foods with high PPO activity, including beet greens.

Ottaviani added that these findings could open the door to more studies on how food preparation affects nutrient absorption. For instance, tea is a major dietary source of flavanols, and the way it is brewed could alter how many of those compounds become available for the body to absorb.

"This is certainly an area that deserves more attention in the field of polyphenols and bioactive compounds in general," said Ottaviani.

Jodi Ensunsa, Reedmond Fong, Jennifer Kimball and Alan Crozier, all affiliated with the UC Davis Department of Nutrition and researchers affiliated with the UC Davis Department of Internal Medicine, University of Reading, King Saud University and Mars, Inc. contributed to the research.

The study was funded by a research grant from Mars, Inc., which collaborates with researchers to study potential benefits of cocoa flavanols for human health.

At the University of California, San Francisco (UCSF), neuroscientist Jennifer Mitchell, PhD, is leading research into innovative treatments for conditions such as anxiety, depression, PTSD, impulsivity, stress, and addiction. She believes a new approach could help where standard therapies fall short -- and early results are encouraging.

This potential breakthrough treatment? A carefully developed pharmaceutical form of LSD.

What is generalized anxiety disorder?

Generalized anxiety disorder is a persistent and excessive form of anxiety that feels out of proportion to actual events or situations. It interferes with daily functioning, affecting relationships, work, and overall quality of life.

People living with GAD may struggle to focus, make decisions, or remember information, making it difficult to manage responsibilities at work or home. The condition can also lead to fatigue, irritability, and secondary depression. Many individuals hesitate to leave their homes for fear of feeling trapped, embarrassed, or helpless in social or public settings.

How is it different from day-to-day anxiety?

A hallmark of generalized anxiety disorder is that it manifests as physical symptoms. Persistent worry activates the body's fight-or-flight response, triggering stress hormones that cause physical effects. Patients may have muscle tension and rapid breathing, and report symptoms like headaches and insomnia, ringing in the ears, and cardiovascular, respiratory, and gastrointestinal issues.

How is generalized anxiety disorder treated?

It's usually treated with medications like Zoloft and Paxil that boost and stabilize the neurotransmitter serotonin, leading to reduced anxiety and enhanced emotional well-being. These medications have been found to reduce symptoms by an average of 1.25 points on the 56-point anxiety scale -- insufficient to make significant difference for at least some patients.

Why LSD?

LSD as well as other psychedelics, have tremendous potential to shift mood and emotions when used in a controlled, therapeutic setting. We have seen this in a previous trial of Ecstasy to treat PTSD.

The pharmaceutical formulation of LSD is MM120. Its primary mechanism is to promote neuroplasticity in the brain, potentially altering negative thought patterns. It also increases communication between brain regions that may address the rigid thinking that underlies GAD.

How effective is MM120?

In an earlier phase of the study, published in JAMA, the effects of a single dose of MM120 were evaluated over a 12-week period in approximately 200 participants with moderate-to-severe generalized anxiety disorder. The drug significantly alleviated symptoms, reducing them by five to six points on the anxiety scale in addition to the effects of placebo. That's quite significant and enough to reclassify moderate generalized anxiety disorder as mild in some cases.

Were there side effects?

Participants were carefully monitored by medical staff during the period after the drug was administered. Side effects were generally mild or moderate and included hallucinations, visual distortions, nausea, and headache. It's important to note, these were more prevalent using the highest dosage -- which we will not be using since it was found to be no more effective. Nausea is a common side effect with psychedelics, but this was reduced by restricting participants to a light breakfast and treating them proactively with an anti-nausea medication.

What challenges do you face recruiting participants for the study?

We are looking for people with moderate-to-severe general anxiety disorder, so typically those with disabling symptoms who are reluctant to leave their home. Ironically, people who would best qualify are least likely to show up. Participants are screened by very skilled clinicians who probe and observe body language and carefully build a rapport. We hope this builds trust and enables participants to be vulnerable and reflective.

Published on October 22 in The Lancet, the comprehensive review analyzed existing studies on non-celiac gluten sensitivity (NCGS). Researchers aimed to clarify why people experience symptoms after eating foods that contain gluten even though they do not have celiac disease. Symptoms such as bloating, abdominal pain, and fatigue are common among those who report gluten sensitivity.

Most Symptoms Aren't Caused by Gluten

Associate Professor Jessica Biesiekierski from the University of Melbourne, who led the study, explained that the results challenge long-held assumptions about the condition.

"Contrary to popular belief, most people with NCGS aren't reacting to gluten," she said. "Our findings show that symptoms are more often triggered by fermentable carbohydrates, commonly known as FODMAPs, by other wheat components or by people's expectations and prior experiences with food."

When researchers compared reactions in carefully controlled studies, they found that only a small number of people showed genuine gluten responses. Overall, reactions were no different from those caused by a placebo.

A New Definition for Gluten Sensitivity

According to Biesiekierski, recent evidence shows that people with irritable bowel syndrome (IBS) who think they are gluten-sensitive often react in similar ways to gluten, wheat, and placebo. "This suggests that how people anticipate and interpret gut sensations can strongly influence their symptoms," she said.

Taken together, the findings indicate that NCGS is part of a broader gut-brain interaction spectrum, more closely related to conditions like IBS than to a gluten disorder.

Implications for Public Health and Treatment

The research team, which included scientists from Australia, The Netherlands, Italy, and the United Kingdom, said the results have important consequences for how gut-related symptoms are managed. They may influence not only medical diagnosis and dietary advice but also future public health messaging.

"Millions of people around the world avoid gluten believing it harms their gut, often after experiencing real symptoms that range from mild discomfort to severe distress," Biesiekierski said. "Improving our scientific and clinical understanding of a condition affecting up to 15 percent of the global population is incredibly important."

Toward More Accurate Diagnosis and Personalized Care

Associate Professor Jason Tye-Din, Director of the Snow Centre for Immune Health and a gastroenterologist at the Royal Melbourne Hospital, said the updated understanding will help clinicians better identify and treat people with NCGS.

"Distinguishing NCGS from related gut conditions is essential for clinicians to offer accurate diagnosis and individualised care, as well as treating underlying drivers," he said. "This review supports a more personalized, evidence-based approach to gut health and avoids unnecessary dietary restriction."

Rethinking Gluten Messaging

Biesiekierski added that successful management of NCGS should combine dietary changes with psychological support while maintaining proper nutrition.

"We would like to see public health messaging shift away from the narrative that gluten is inherently harmful, as this research shows that this often isn't the case," she said. "These findings additionally call for better diagnostic tools, more rigorous clinical pathways and research funding in this field, as well as improved public education and food labeling."