It contributes next to no calories to our diets, and it helps make our stool soft and bulky so it leaves our bodies on a good note [1].
Dietary fiber is a super nutrient you’d be hard-pressed to find any dietitian advocating against. Research into dietary fiber started back in the 1950s [2]. But it seems that the more we research it, the more health benefits we uncover.
Before we dig into those, let’s define what dietary fiber is exactly.
Dietary fiber is edible, plant-based carbohydrate that’s resistant to digestion and absorption in the small intestine.
We have two main types of dietary fiber: soluble and insoluble. Both are good for our health [3].
However, while most people recognize dietary fiber for its heroic work in our digestive system, that’s just the tip of the iceberg. The ripple effects of health benefits that start from right there can extend to our whole body. So much so that dietary fiber promotes healthy aging [4].
Healthy aging is a continuous process of optimizing opportunities to maintain and improve physical and mental health, independence, and quality of life throughout the life course. Pan American Health Organization
The emphasis on the entire life course is why we love this definition of healthy aging. And it’s especially relevant to our topic because dietary fiber supports healthy aging — for all ages. The effect is far from exclusive to Grandma taking Metamucil to get a bowel movement.
To put things into perspective, let’s visit one of the most remarkable studies nutrition studies ever. It gathered data from 185 prospective studies, 58 clinical trials, and get this 135 million person-years. That humongous body of data showed that high consumers of dietary fiber had a 15–30% decrease in all-cause mortality than low consumers [5].
It’s that powerful, folks. Now, let’s zoom in and discover how dietary fiber is able to pull that life-extending feat off. So without further ado, here are seven ways dietary fiber promotes healthy aging.
1- It Nourishes the Gut Microbiome
Believe it or not, we’re more microbe than human. For every 30 trillion human cells, we have about 39 trillion microbial cells, collectively known as the microbiome [6].
Dietary fiber is the primary energy source of the microbiome in our gut, helping maintain a healthy composition of different species. Disruption of this balance, or dysbiosis, is a hallmark of aging. That can lead to inflammaging, a low-grade inflammation associated with age, and affecting our entire body. But here’s the good news: dietary fiber can reverse age-associated dysbiosis and potentially inflammaging [7].
Additionally, when our microbiome processes dietary fiber, it produces beneficial molecules like short-chain fatty acids (SCFAs). These SCFAs regulate various biological processes and induce numerous health benefits, some of which we’ll explore next [7].
2- It Lowers the Risk of Several Cancers
Increasing your fiber intake by just 10g per day can significantly reduce your risk of various cancers. We’re talking about a 13% reduction in colorectal cancer, 5–7% in breast cancer, a whopping 44% in gastric cancer, and 31% in esophageal cancer. And it doesn’t stop there. A diet rich in fiber is also associated with an 11% decrease in prostate cancer risk and a 16% decline in renal cell carcinoma [8].
So, how does fiber pull this off? For starters, insoluble fiber increases the viscosity and bulk of our stool, trapping carcinogenic molecules and reducing their contact with our colon cells. This leads to a decrease in the production of harmful compounds [9].
But there’s more. Remember the SCFAs we just talked about? They play a crucial role too. SCFAs lower the pH in the colon, triggering the programmed death of precancerous cells by inhibiting enzymes that regulate the expression and activity of proteins involved in cancer progression [9].
3- It Protects from Heart Disease
Here’s a heartwarming fact: just a 7–10g increase in daily fiber intake can reduce cardiovascular disease risk by 9–11% [10]. Additionally, a review of eight trials found that upping fiber intake reduces both systolic and diastolic blood pressure by 1.9 mm Hg and 1.8 mm Hg, respectively [11]. Another study found that fiber lowers total cholesterol by 8.9 mg/dL and LDL (aka bad) cholesterol by 5.4 mg/dL [12].
And the benefits don’t stop at the individual level. The impact of fiber on healthy aging has societal implications too. A cost-of-illness analysis revealed that each 1g increase in daily fiber consumption can lead to an annual saving of up to $51.1 million in heart disease care costs [13].
4- It Helps in Managing Diabetes
An umbrella review of 16 meta-analyses reveals that high fiber intake can significantly reduce the relative risk of type 2 diabetes by up to 19%, leading to better glycemic control and insulin sensitivity [14].
Mechanisms behind this risk reduction also point to the influence of SCFAs which improve insulin secretion and HbA1c levels by enhancing the natural production of gut peptides like GLP-1 — a compound mimicked by popular diabetes drugs such as Wegovy, Ozempic, and Mounjaro [15].
The same cost-of-illness analysis we discussed earlier also estimated that just 1g of dietary fiber consumption can lead to an annual saving of up to $92.1 million in type 2 diabetes care costs [13].
5- It Supports Weight Loss
High fiber intake seems a promising strategy for weight loss. A review of 32 trials found significant weight loss in groups consuming more fiber [16].
How does it work? Fiber reduces caloric density, slows food ingestion, increases eating effort, promotes satiety, and slightly interferes with energy absorption. This prevents excessive food intake and fat accumulation [17].
Plus, a 10g daily increase in soluble fiber can reduce visceral fat by 3.7% over five years, highlighting fiber’s role in obesity management [18].
6- It Promotes Brain Health
A two-decade study of over 3700 adults found a direct correlation between fiber intake and dementia rates. Those consuming the most fiber (18-65g daily) had a 26% lower risk of dementia compared to those consuming the least (2-10g daily) [19]. Even in adults carrying the APOE-E4 gene variant, which increases Alzheimer’s risk, another study has found that higher fiber intake was associated with better cognitive skills in old age [20].
The brain-boosting effects of fiber extend to children too, with studies showing improved multitasking, working memory, and focus in children on a high-fiber diet [21].
One potential mechanism behind these benefits is the reduction of inflammation in the brain’s microglia, the cells responsible for cleaning up brain debris, by a high-fiber diet [22].
7- It Boosts Mental Health
Research from 18 publications reveals a compelling link between fiber intake and depression risk. Specifically, each 5g increase in daily fiber intake corresponds to a 5% reduction in depression risk [23]. Also, a clinical trial found that consuming a specific type of fiber significantly improved well-being, mood, and cognitive scores compared to a placebo [24].
This could be attributed to the gut microbiome and the link it has to the brain: the brain-gut-axis. Through this axis, the gut microbiome produces neurotransmitters like serotonin and GABA, which are then transported to the brain. Lower serotonin levels are associated with mood deterioration and depression relapse, while reduced GABA concentrations are linked to anxiety disorders and depression. So, increasing the levels of these neurotransmitters in the brain with the help of the gut microbiome brings about a pivotal boost in mental health [25].
How to Add More Fiber to Your Diet
Despite the plethora of benefits of dietary fiber we’ve explored, the American Society for Nutrition reports that only 5% of men and 9% of women are meeting the recommended daily intake [26]. The Food and Drug Administration suggests a daily fiber intake of 28g for adults on a 2,000-calorie diet [27].
Luckily, dietary fiber isn’t hard to find. Excellent sources of dietary fiber include whole-grain breads and cereals, fruits, vegetables, beans, peas, lentils, nuts, and seeds.
To seamlessly incorporate more fiber into your diet, consider these tips:
- Make fruit salad: A delicious way to combine multiple high-fiber fruits.
- Eat whole fruit, not just the juice: The fiber is in the pulp and skin.
- Include veggies in meals, and eat them first: This can increase your vegetable (and thus, fiber) intake.
- Eat pulses, such as beans, lentils, and peas, at least three times a week: These are excellent sources of fiber.
- Snack on nuts, seeds, and fruit: Healthy, high-fiber options for between meals.
- Replace refined grains like white rice with whole grains like brown rice: Whole grains provide more fiber.
- Check nutrition fact labels: Aim for at least 5g of fiber per serving.
Remember, it’s important to increase your dietary fiber intake gradually to avoid digestive discomfort, and to drink plenty of fluids to help fiber do its job.
Let’s give dietary fiber the standing ovation it deserves by making it a staple in our diets.
After all, if there’s one thing we’ve learned today, it’s that a little fiber today keeps the aging away!
References:
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