Polysaccharides, special carbohydrates found in plants and fungi, may help reduce depression and anxiety by changing gut bacteria and reducing brain inflammation, according to research reviewed by Gram. Studies of goji berries and astragalus root showed antidepressant effects in lab and animal experiments, with some human trials reporting mood improvements after 4 to 8 weeks. However, these compounds are not yet proven treatments, and larger human studies are needed before doctors can confidently recommend them for mood disorders.
Scientists are discovering that special carbohydrates called polysaccharides, found in plants and fungi, might help improve depression and anxiety. According to Gram Research analysis, these natural compounds work by changing your gut bacteria, reducing inflammation in your brain, and helping your body make mood-boosting chemicals. While early research shows promise, especially with extracts from goji berries and astragalus root, doctors say we need bigger, better studies before recommending them as official treatments. This review examines how these plant compounds could become a new way to support mental health through food.
Key Statistics
A 2026 review in Critical Reviews in Food Science and Nutrition found that polysaccharides from goji berries and astragalus root demonstrated antidepressant and anti-anxiety effects in both experimental studies and clinical trials by modulating gut bacteria and reducing brain inflammation.
Research reviewed by Gram showed that polysaccharides work through multiple pathways including reducing oxidative stress, promoting neurotransmitter synthesis, and strengthening immune function, though most human evidence comes from small studies lasting 4 to 8 weeks.
A 2026 review identified that while polysaccharide supplements are generally safe with few side effects, variability in chemical composition and study methods across existing research prevents definitive clinical recommendations until larger-scale human trials are completed.
The Quick Take
- What they studied: Whether special carbohydrates from plants, fungi, and algae can help reduce depression and anxiety symptoms
- Who participated: This was a review article that looked at many different studies, including lab experiments, animal studies, and some human trials. No single group of participants, but rather a summary of existing research
- Key finding: Polysaccharides from goji berries and astragalus root showed antidepressant and anti-anxiety effects in both lab studies and some human trials, likely by changing gut bacteria and reducing brain inflammation
- What it means for you: These plant compounds might eventually help with mood disorders, but they are not yet proven treatments. Talk to your doctor before using them alongside other mental health treatments
The Research Details
This is a review article, meaning scientists read and summarized many other studies on the same topic rather than conducting their own experiment. The researchers looked at three types of evidence: lab studies where polysaccharides were tested in cells, animal studies where researchers gave these compounds to mice or rats, and human clinical trials where people actually took the compounds and reported their mood changes.
The review focused on understanding how polysaccharides might work in the body. Researchers examined whether these compounds change the bacteria in your gut, reduce swelling in the brain, help your brain make mood chemicals like serotonin, or reduce harmful molecules called free radicals that damage cells.
By combining findings from many different studies, the researchers could see patterns and identify which polysaccharides showed the most promise for mood support.
Review articles are important because they help scientists and doctors see the big picture. Instead of looking at one small study, a review combines many studies to show what the overall evidence suggests. This approach helps identify which treatments might actually work and which areas need more research before people should try them
This review was published in a well-respected scientific journal in 2026. However, the researchers noted that the studies they reviewed had important differences: some used different types of polysaccharides, some tested different doses, and some measured mood in different ways. These differences make it harder to draw firm conclusions. The researchers also pointed out that most human studies were small, meaning we need larger trials with more participants to be confident in the results
What the Results Show
Polysaccharides from goji berries (Lycium barbarum) and astragalus root (Astragalus) showed the strongest evidence for helping with depression and anxiety. In lab studies, these compounds reduced inflammation markers and helped brain cells survive better. In animal studies, mice and rats given these polysaccharides showed less anxiety-like behavior and more interest in activities, similar to how antidepressant medications work.
The research suggests polysaccharides work through multiple pathways in the body. First, they change the types of bacteria living in your gut, and these bacteria communicate with your brain through what scientists call the gut-brain axis. Second, they reduce inflammation in the brain and body, which is linked to depression. Third, they help your brain make more serotonin and other mood-regulating chemicals. Fourth, they protect brain cells from damage caused by oxidative stress, a harmful process that happens in depression.
Some human studies showed that people taking polysaccharide supplements reported improved mood and less anxiety over several weeks. However, these human studies were generally small, with fewer than 100 participants each, and not all used the same measurement methods.
The review found that polysaccharides from other sources, including certain mushrooms and seaweed, also showed potential benefits in lab and animal studies. These compounds appeared to strengthen the immune system and reduce overall inflammation in the body, which could indirectly support mental health. The researchers also noted that polysaccharides are generally safe with few side effects, making them potentially attractive as a dietary approach to mood support
This research builds on growing interest in the gut-brain connection for mental health. Previous studies showed that gut bacteria influence mood through chemical signals, and that inflammation is involved in depression. This review adds to that knowledge by showing that plant polysaccharides might be a natural way to improve both gut bacteria and reduce brain inflammation. However, the evidence is still earlier stage than for established depression treatments like medications or therapy
The researchers identified several important limitations. Different studies used different types of polysaccharides with different chemical structures, making it hard to know which specific compounds work best. Studies also used different doses and treatment lengths, so we do not know the optimal amount or duration. Most human studies were small and short term, lasting only a few weeks. Some studies did not have a control group for comparison. The review also noted that many studies came from Asia, where these plants are traditionally used, which might bias results. Finally, most human evidence is preliminary, and we need larger, longer studies before doctors can confidently recommend these compounds for mood disorders
The Bottom Line
Polysaccharides show promise for mood support based on early research, but they should not replace proven treatments like therapy or medication. If you are interested in trying polysaccharide supplements, talk to your doctor first, especially if you take other medications. Eating foods naturally rich in polysaccharides, like goji berries, mushrooms, and whole grains, is a safe way to potentially benefit while researchers conduct larger studies. Confidence level: Low to moderate for mood support, pending larger human trials
People with depression or anxiety who want to explore natural options alongside their current treatment should know about this research. People interested in preventive nutrition and mental health may want to follow this area as it develops. However, people with severe depression or anxiety should continue working with mental health professionals rather than relying only on dietary supplements. Pregnant women and people taking blood thinners should check with their doctor before using polysaccharide supplements
In animal studies, mood improvements appeared within 2 to 4 weeks. The few human studies that exist suggest similar timelines, with people reporting better mood after 4 to 8 weeks of taking supplements. However, these are early estimates, and larger studies may show different results. Mental health improvements typically take time, whether from medication, therapy, or dietary changes
Frequently Asked Questions
Can polysaccharides from plants actually help with depression?
Early research suggests they may help by changing gut bacteria and reducing brain inflammation. Goji berries and astragalus showed promise in lab and animal studies, with some human trials reporting mood improvements after 4 to 8 weeks. However, these are not yet proven treatments, and larger studies are needed
What foods contain polysaccharides that might improve mood?
Goji berries, astragalus root, mushrooms, seaweed, and whole grains contain polysaccharides. These foods are safe to eat regularly as part of a healthy diet while researchers continue studying their mood effects
Are polysaccharide supplements safe to take with antidepressants?
Polysaccharides are generally safe with few side effects, but you should talk to your doctor before combining them with antidepressants or other medications to avoid potential interactions
How long does it take to see mood improvements from polysaccharides?
In the few human studies available, people reported mood improvements after 4 to 8 weeks of taking polysaccharide supplements. However, these timelines are preliminary and may vary based on individual factors and the specific polysaccharide used
Should I stop my depression medication and try polysaccharides instead?
No. Polysaccharides are not proven replacements for established depression treatments. Continue working with your mental health provider. You might discuss adding polysaccharide-rich foods as a complementary approach alongside your current treatment
Want to Apply This Research?
- Log daily mood on a 1 to 10 scale and track which polysaccharide-rich foods you ate that day. After 4 weeks, review whether days with more polysaccharide intake correlate with better mood scores
- Add one polysaccharide-rich food to your daily diet: goji berries in oatmeal, mushrooms in dinner, or a seaweed snack. Track this addition and your mood to see if you notice a pattern over 6 to 8 weeks
- Create a weekly mood check-in that includes a 1 to 10 mood rating, sleep quality, anxiety level, and a log of polysaccharide-rich foods eaten. Review trends monthly to see if dietary changes correlate with mood improvements
This review summarizes early-stage research on polysaccharides and mood. These compounds are not approved by the FDA as treatments for depression or anxiety. If you have depression, anxiety, or other mental health concerns, consult a qualified mental health professional or doctor before making changes to your treatment plan. Polysaccharide supplements should not replace proven treatments like therapy or medication. Pregnant women, nursing mothers, and people taking blood thinners should consult their doctor before using polysaccharide supplements. Individual results may vary, and larger clinical trials are needed to establish safety and effectiveness.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.