A diet with more fiber-rich fruits, vegetables, and whole grains may promote mental well-being in women, suggests new research.
In a world where different fad diets fall in and out of favor, a high-fiber diet consistently checks every box when it comes to fueling good health. Eating foods that are higher in fiber can reduce the risk of chronic disease and make you feel full longer, which can help you stay at a healthy weight, according to the U.S. Food and Drug Administration (FDA).
If those health benefits aren’t already enough to have you reaching for a bowl of berries or handful of edamame, new research suggests that women who eat a diet higher in fiber are less likely to be depressed than women who consume less fiber.
The study, published on January 6, 2021, in Menopause: The Journal of the North American Menopause Society, wasn’t designed to discover the why behind the link, but the authors speculate it’s because of fiber’s positive impact on gut health.
Fiber May Benefit the Gut Microbiome
“Previous studies have indicated that dietary fiber intake may modulate the richness and diversity of the gut microbiota, and this change may promote brain health by affecting neurotransmission,” says Jung-Ha Kim, MD, PhD, an associate professor at Chung-ang University College of Medicine in Seoul, Republic of Korea, and one of the authors of the study.
What’s So Fantastic About Fiber?
A lot, according to Kristi Tough DeSapri, MD, an assistant professor of medicine at Northwestern University and a physician at the Northwestern Medicine Center for Sexual Medicine and Menopause, both in Chicago. Dr. DeSapri was not involved in the study. “Increasing the amount of fiber by eating more fruits, vegetables, and whole grains is good for you. It’s been shown to decrease the risk of cardiovascular disease, diabetes, and breast cancer, and it’s good for gastrointestinal health,” she says.
Dietary fiber is a type of carbohydrate that is composed of sugar molecules linked together, according to the FDA. Its composition makes it harder to digest than other carbohydrates.
In fact, fiber is a staple in plant-based diets such as vegan, vegetarian, and Mediterranean diets, and these approaches are also associated with disease prevention and management, in addition to a healthy weight.
Estrogen Levels Fluctuate and Drop in Midlife
Along with estrogen levels, a woman’s fertility declines with age, until the permanent cessation of menstruation, which most reach around age 51. When women are still having a regular menstrual cycle, estrogen levels rise and fall during different times of the month, according to the Cleveland Clinic.
When a woman enters perimenopause, the long lead-up to menopause, there is a significant decrease in estrogen production. Menopause, the permanent cessation of menstruation, is official when a woman has gone without a period for 12 months in a row, and estrogen declines even further during this phase.
Study Looks at Dietary Fiber’s Ability to Influence Mood Issues
To find out whether consuming more fiber had an impact on the likelihood of depression, investigators used data from the Korea National Health and Nutritional Examination Survey from 2014, 2016, and 2018.
Unlike Other Studies, This One Distinguished Women Who Had Reached Menopause From Women Who Had Not
Although previous studies have looked at fiber and mental health, this is the first known study to separate premenopausal and post-menopausal women into their own categories to see if that might change the association.
A total of 5,807 women were included, with a median age of 47. Of those women, 2,949 were premenopausal and 2,858 were post-menopausal. Fiber intake was calculated by asking participants to recall what they had eaten in the previous 24 hours.
Depression was assessed with the Patient Health Questionnaire-9, a short survey that’s commonly used to screen for depression. The form asks about mood, trouble sleeping, energy and appetite levels, and ability to enjoy doing things.
Researchers found that a higher dietary intake of fiber was associated with a lower risk of reporting symptoms of depression. After adjusting for variables that could impact the results, such as marital status, household income, education level, weight, smoking, and chronic diseases, researchers found that perimenopausal women still had a lower risk for depression, but no significant difference was found in menopausal women who ate more fiber.
Fiber Linked With ‘Modest’ Effect on Depression in Premenopausal Women
“I think the overall message of the study is that more fiber intake overall was associated with a decreased risk of depression,” says DeSapri. Once the researchers controlled for all the variables listed above, there was still a modest reduction in depression. “We are not talking about huge reductions; it was about a 6 percent relative reduction in premenopausal women, and for post-menopausal women there was about a 2 percent relative reduction, which wasn’t enough to be statistically significant,” she says.
These reductions, though modest, tell us a little about what could be a trend, and that more fiber intake may decrease the risk of depression, says DeSapri. “It underscores what we already know, which is that eating more fruits, vegetables and insoluble fiber has been associated with decreased rates of depression,” she says.
A healthy diet that includes high intakes of fruit, vegetables, and whole grains was associated with a decreased risk of depression in a review published in July 2017 in Psychiatry Research.
More Fiber = Less Depression? It May Not Be That Simple
The findings in this research are interesting, but the authors make a lot of assumptions, says Stephanie Faubion, MD, MBA, the director of the center for women’s health at the Mayo Clinic in Rochester, Minnesota, and medical director of the North American Menopause Society (NAMS). Dr. Faubion was not involved in the new research.
“They’re assuming that the direction of the association only goes one way, that the fiber intake is impacting the depression, and I think that’s incorrect,” she says.
Which Comes First, Depression or a Low Fiber Diet?
It may be that depressed people have a poorer diet and eat less fiber as a result of their depression, says Faubion. “Maybe they are too depressed to cook or seek out healthy meals. People tend to take care of themselves better, whether that’s a better diet or getting regular exercise, when their mood is better,” she says. When people are depressed, they often reach for less healthy options, she adds.
“The last thing I want people to take from these findings is that if you improve your diet, you can treat your depression — that is a dangerous message,” says Faubion. People who are feeling symptoms of depression should speak with their doctor and get the medically appropriate treatment, she adds.
When You Eat Better, You Feel Better
That isn’t to say that there isn’t a brain-gut connection, says Faubion. “I believe that there is a connection, and what you put in your mouth is definitely important and can definitely impact your mood,” she says.
“What you eat is going to affect your microbiome, and a heathy diet can help that be a positive connection,” says Faubion.
What Is the Relationship Between Estrogen and Fiber?
It’s not clear why the association between more fiber and fewer symptoms of depression existed in the premenopausal group. Previous studies have indicated that there might be an interaction between estrogen and gut microbiota, says Dr. Kim.
“Because post-menopausal women experience estrogen depletion, the decreased interaction between estrogen and the gut microbiota may be related to the insignificant association between dietary fiber intake and depression in post-menopausal women,” she says.
A study published in May 2020 in Frontiers in Neuroscience found that consuming more dietary fiber was associated with having fewer symptoms of depressive symptoms in premenopausal women, but not early perimenopausal women. Premenopausal was defined as menstrual bleeding in the previous three months with no change in cycle regularity in the past year, and early perimenopausal was defined as menstrual bleeding in the last three months accompanied by cycle irregularity in the past year.
Whether that interaction between estrogen and gut microbiota is driving these results isn’t clear, says Faubion. “It is true that estrogen impacts every organ and tissue in the body, and so it could be that there’s a differential effect based on estrogen, but that isn’t proven, and we don’t know why or how that would be the case,” she says.
Hot Flashes, Other Menopausal Symptoms May Improve With More Fiber
Although the benefits for postmenopausal women weren’t shown to be statistically significant in this study, it doesn’t mean that those women shouldn’t try to increase their fiber intake if they aren’t getting the recommended amount, says DeSapri. “There are lots of benefits to a diet rich in fiber after the menopause transition,” she adds.
A large observational study published in the journal Menopause found that consuming more fiber as part of a dietary intervention to achieve weight loss was shown to reduce hot flashes by nearly 20 percent in postmenopausal women, points out DeSapri.
Adding Fiber to Your Diet Can Have Multiple Benefits
If you’re trying to be healthier in the new year, adding fiber to your diet can be a good way to do that, says Faubion. And, as a bonus, your mental health may improve a little bit, she adds.
The key to successfully adding fiber to your diet is to up your intake slowly, says DeSapri. “If you have a diet where you don’t eat much fiber and you start eating a cup of beans every day, you’re probably going to have some gas and bloating,” she says.
While most Americans don’t eat nearly enough fiber, the recommended daily amount (RDA), or target, for women who consume 2000 calories a day is 28 grams (g). A good general goal, says Despari, is 25 (g) a day.
Here’s Dr. DeSapri’s advice on upping your fiber intake to reach that target:
- Try adding a high fiber food such as steel-cut oatmeal (¼ cup serving of dry oats delivers 5 g of fiber) or beans every other day at first.
- Add chia seeds to a smoothie or sprinkle on top of yogurt. One tablespoon of these seeds gives you 5 g.
- Eat fruit that’s easy to keep handy such as an apple (5 g of fiber in a large one), orange, or banana (worth roughly 3 g of fiber).
- Whole grains can be a good source of fiber, but check the nutrition label because fiber content can vary depending on the type of bread or wrap.
This article was originally published on Everyday Health.