How Mount Pleasant Residents Can Improve Gut Health Naturally
Ashley Harwyn, PA-C, ABAAHP | Published August 4, 2025 | Last updated October 6, 2026 | 22 min read
The gut habits with the most research behind them are everyday ones: fiber, fermented foods, movement, and sleep. Here is what each one has been shown to do, and how to start.
One habit at a time, starting with the ones that have the most research behind them.
For most adults in Mount Pleasant and the wider Charleston area, the natural gut habits with research behind them are plain ones: eat more fiber, add fermented foods you actually like, get 7 or more hours of sleep, and stay physically active. Probiotic capsules are a narrower case: the American Gastroenterological Association suggests specific strains for only a handful of situations.[1][4][7][8][9] If you want help turning that into a plan that fits your symptoms, that is what a gut health visit is for.
This guide is about the daily side of gut care. It walks through what each habit has been shown to do in people, how strong that proof is, and how to start gradually, as NIDDK advises for fiber.[1] Where the research is thin, we say so. If you have symptoms that worry you, read our guide on gut signs that need a clinician first. It lists the warning signs that federal health agencies name. This guide is written for people without those signs.
Key takeaways
Adults should get 22 to 34 grams of fiber a day depending on age and sex, added a little at a time with plenty of liquids.[1]
In long-term observational studies pooled in a Lancet review, people who ate the most fiber had 15% to 30% lower rates of death from any cause, heart disease, type 2 diabetes, and colorectal cancer than those who ate the least.[2]
In a 17-week randomized study, a diet high in fermented foods steadily raised gut microbial diversity and lowered markers of inflammation.[4]
Exercise and sleep are linked to gut bacteria in small studies, and both have health benefits beyond the gut that the CDC and the federal activity guidelines describe.[5][6][7][8]
The AGA advises using probiotics for IBS, Crohn's disease, ulcerative colitis, or C. difficile infection only within a clinical trial.[9]
Many probiotics are sold as dietary supplements, which do not need FDA approval before they are marketed.[10]
Section 01 / Defining the goal
What does it actually mean to improve your gut health?
The phrase gets used for almost anything, so it helps to define it. Your gut microbiome is the community of bacteria, yeasts, and other microbes living in your digestive tract. The National Center for Complementary and Integrative Health calls the wider community that lives on and in us “a hot topic for research,” and notes that much remains to be learned about whether probiotics are helpful and safe for various conditions.[10] In other words, by NCCIH's own account, much of this science is still being worked out.[10]
Researchers often measure diversity, meaning how many different kinds of microbes show up in a stool sample. Higher diversity is generally treated as a good sign, and one research group has described lower diversity and higher inflammation as common in industrialized societies.[4] Diversity is a research measure, though, and the studies cited here do not give a single number that defines a healthy gut.
Practical questions are easier to track at home. Are your bowel movements regular and comfortable? Has bloating eased? Are you eating a wider range of foods without trouble? Over the long term, the fiber research cited below tracks outcomes such as heart disease, type 2 diabetes, and colorectal cancer.[2]
One more definition matters. Probiotics are live microorganisms meant to have a health benefit, found in yogurt and other fermented foods as well as in supplements.[10] Prebiotics are something different: food components you cannot digest that feed helpful microbes.[10] Fiber comes first in this guide for a simpler reason: of the studies cited here, the fiber research is by far the largest.[2]
Section 02 / Evidence ranked
Which gut habits have the strongest evidence?
Not every piece of gut advice stands on the same ground. Some habits rest on hundreds of studies and millions of person-years of data. Others rest on one small trial or a pattern seen in volunteers. The grid below sorts the main options by the kind of evidence behind them, so you can see how strong each one is.
Sources: NIDDK, Eating, Diet, and Nutrition for Constipation; Reynolds A et al., The Lancet, 2019. Your own target depends on age and sex.
Habit
What the research found
Strength of the evidence
A realistic first step
Eating more fiber
15% to 30% lower rates of death from any cause, heart disease, type 2 diabetes, and colorectal cancer in the highest fiber eaters; benefits were greatest at 25 to 29 grams a day[2]
Moderate certainty, from 185 prospective studies and 58 clinical trials[2]
Add one fiber food a day, a little at a time, and drink more liquids[1]
Eating many kinds of plants
People eating more than 30 plant types a week had different gut bacteria than people eating fewer than 10[3]
Ask a clinician which strain, for what, and for how long
Habit check
Which of these sound like your week?
Tap each statement that is true for you. This is not a diagnosis. It shows which everyday habits have the most room to grow, so you know where to start or what to bring up with Ashley.
Read the grid from top to bottom and a pattern appears. The habit with the most data behind it here is fiber.[2] Probiotic supplements, by contrast, are suggested by the AGA only as named strains for a few specific situations.[9] That does not make probiotics useless. It means the evidence cited here is strongest for food, and that a supplement fits best when there is a specific reason for it, such as the uses the AGA names.[9]
It also helps to separate gut microbes from gut outcomes. Several rows describe changes in bacteria, not proof that you will feel better or live longer. The fiber row is different, because it tracks hard outcomes like heart disease and cancer in very large groups of people.[2]
Section 03 / Fiber first
How much fiber do you need, and how do you add it gradually?
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says adults should get 22 to 34 grams of fiber a day, depending on age and sex.[1] Good sources on its list include whole grains such as oatmeal and whole wheat bread, legumes such as lentils, black beans, and chickpeas, fruits such as berries, pears, oranges, and apples with the skin on, vegetables such as carrots, broccoli, green peas, and collard greens, and nuts such as almonds, peanuts, and pecans.[1] These are ordinary grocery-store foods, so the change is mostly about eating more of them.
Why push fiber so hard? In a set of systematic reviews published in The Lancet and funded in part by the World Health Organization, researchers pooled just under 135 million person-years of data from 185 prospective studies and 58 clinical trials.[2] In the observational data, people with the highest fiber intake had 15% to 30% lower rates of death from any cause and from cardiovascular disease, and of coronary heart disease, stroke, type 2 diabetes, and colorectal cancer, compared with those with the lowest intake.[2] The clinical trials showed lower body weight, systolic blood pressure, and total cholesterol with higher fiber intake.[2] The risk reductions were greatest at 25 to 29 grams a day.[2]
Two honest caveats. First, most of those findings come from observational studies, which show association rather than proof, although the authors judged the certainty of the fiber evidence as moderate and the dose-response pattern as strong enough that the links could be causal.[2] Second, the review studied the general population, not people already living with chronic disease.[2]
How to add fiber gradually
NIDDK advises adding fiber a little at a time so your body gets used to the change, and drinking water and other liquids to help the fiber work.[1] In practice, that looks like this:
Start with one fiber food from the NIDDK list, such as oatmeal at breakfast or a handful of almonds in the afternoon.[1]
Add the next one only after your body has had time to get used to the first.[1]
Drink water or other liquids along with the extra fiber.[1]
If you are unsure how much fiber is right for you, NIDDK suggests talking with a health care professional, such as a dietitian, to plan meals.[1]
Swap refined grains for whole grains as you go. The same review found similar benefits for whole grains.[2]
Why variety may matter, not just grams
The American Gut Project, a citizen science study with samples from more than 10,000 people, asked volunteers how many different plants they eat in an average week.[3] Researchers compared people who ate more than 30 types with people who ate fewer than 10, and found differences in their gut bacteria, including several microbes linked with eating more than 30 types that may produce short-chain fatty acids.[3] That is a correlation in self-selected volunteers who mailed in their own samples, so it cannot prove that variety causes a healthier gut.[3] If you want to try counting, the survey counted generously: each different grain in a multigrain bread counted as a plant, and so did each vegetable in a can of soup.[3]
If you have irritable bowel syndrome or another digestive condition, plan fiber changes with a clinician rather than guess; NIDDK itself suggests planning fiber with a health care professional.[1] Our nutritional therapy service offers weekly coaching, with one or two changes planned for each week.
Section 04 / Fermented foods
Do fermented foods do something fiber does not?
They might, and one randomized study on the question is worth knowing in some detail. In 2021, a Stanford team published a 17-week randomized study in healthy adults, with 18 people assigned to a high-fiber diet and 18 to a diet high in fermented foods.[4] The researchers followed both groups with detailed stool and blood testing, including extensive immune profiling.[4]
The two diets did different things. The high-fermented-food diet steadily increased microbial diversity and decreased markers of inflammation.[4] The high-fiber diet increased the gut's capacity to break down complex carbohydrates, but diversity stayed stable over the study period.[4] The study's main planned measure, an immune response score, did not change, and people on the fiber diet split into three different immune patterns that tracked with how diverse their gut bacteria were at the start.[4]
What should you take from that? Not that fiber is unimportant. The fiber evidence for heart disease, diabetes, and colorectal cancer is far larger than this one trial.[2] The useful lesson is that, in this study, the two diets did different things, and that one small study is a signal, not a promise. The authors themselves framed fermented foods as something that “may be valuable” against the low diversity and higher inflammation common in industrialized life.[4]
What the fermented-food group actually ate
NCCIH lists yogurt and other fermented foods as sources of probiotics.[10] In the Stanford study, people in the fermented-food group ate a mix that included yogurt, kefir, fermented cottage cheese, kombucha, vegetable brine drinks, and fermented vegetables such as kimchi.[4] A few details from the full paper are worth knowing before you copy it:
Nobody switched overnight. Both groups went through a 4-week ramp phase, gradually increasing intake, before a 6-week maintenance phase.[4]
The amounts were large. The fermented-food group went from an average of 0.4 servings a day at the start to 6.3 servings a day by the end of maintenance.[4]
A serving was small: 6 ounces of yogurt, kefir, or kombucha, or a quarter cup of kimchi or sauerkraut.[4]
The fermented-food group reported more bloating by the end of the ramp phase, and that difference was no longer significant by the end of maintenance.[4]
The authors noted they do not know how long the changes they saw would last.[4]
If you have a weakened immune system or are being treated for a serious illness, ask your clinician before adding large amounts of fermented foods or any probiotic product. NCCIH notes that the risk of harm from probiotic microbes is greater in people with severe illness or compromised immune systems.[10]
Section 05 / Sleep and movement
Can sleep and exercise really change your gut?
Studies have found links, but the human evidence is small, so it is worth being precise about what has been shown.
Exercise: changes that faded when training stopped
In a trial at the University of Illinois, 32 previously inactive adults (18 lean and 14 with obesity) completed six weeks of supervised endurance exercise three days a week, building from 30 to 60 minutes a session and from moderate to vigorous intensity.[5] Diet was controlled for three days before each stool sample.[5] Exercise changed the makeup of their gut bacteria in ways that depended on body weight, and it raised fecal levels of short-chain fatty acids in the lean participants but not in those with obesity.[5] Short-chain fatty acids are compounds that certain gut bacteria can produce.[5] Then came the telling part: after a six-week return to inactivity, the changes were largely reversed.[5]
The authors concluded that the changes were contingent on keeping up the exercise.[5] Fortunately, the reasons to keep doing it go far beyond bacteria. The federal Physical Activity Guidelines say adults need at least 150 to 300 minutes of moderate-intensity aerobic activity, such as brisk walking, each week, plus muscle-strengthening activity at least two days a week.[8] The guidelines credit regular activity with helping prevent eight types of cancer, colon cancer among them, and note that any amount of activity has some health benefits.[8]
Brisk walking is one of the examples of moderate-intensity activity the guidelines give, so a walk around your own Mount Pleasant or Charleston neighborhood counts.[8] Bring water along, too, since NIDDK notes that liquids help fiber work better.[1]
Sleep: a link worth respecting, not yet a lever
The sleep evidence is thinner. In one study, researchers tracked the sleep of 26 healthy young men with wrist monitors and compared it with their stool samples.[6] Greater microbial diversity went along with better sleep efficiency and more total sleep time, and with less time awake after first falling asleep.[6] The authors noted that earlier studies on sleep loss and the gut had produced conflicting results, and that because they studied only men, they could not say how well the findings apply to women.[6] The authors also stated that a correlation like theirs cannot pinpoint the direction of the link.[6]
That uncertainty does not change the advice. The CDC recommends 7 or more hours of sleep for adults aged 18 to 60.[7] Its healthy sleep habits include going to bed and getting up at the same time every day, turning off electronic devices at least 30 minutes before bed, avoiding large meals and alcohol before bedtime, skipping caffeine in the afternoon and evening, and exercising regularly.[7] The activity guidelines add that physical activity can improve quality of sleep.[8]
Changed your diet and still uncomfortable? Call 843-981-0870. We can look at what you have tried so far and help you work out whether the next step is a food plan, a test, or a referral.
Section 06 / Probiotics, honestly
Should you take a probiotic? What the AGA guideline actually says
In 2020, the American Gastroenterological Association (AGA) published clinical practice guidelines on probiotics for digestive conditions.[9] The guideline covers C. difficile infection, adults and children taking antibiotics, Crohn's disease, ulcerative colitis, pouchitis, irritable bowel syndrome, acute infectious gastroenteritis in children, and preterm, low-birth-weight infants.[9] Here is what it says, condition by condition:
C. difficile infection, Crohn's disease, ulcerative colitis, and IBS: the AGA recommends using probiotics only in the context of a clinical trial.[9]
Children with acute infectious gastroenteritis: the AGA suggests against using probiotics.[9]
Adults and children taking antibiotics: the AGA suggests specific products for preventing C. difficile infection, namely S. boulardii, a two-strain combination of L. acidophilus CL1285 and L. casei LBC80R, or a particular three-strain or four-strain combination, over no probiotic or other probiotics.[9]
Adults and children with pouchitis: the AGA suggests one specific eight-strain combination.[9]
Preterm, low-birth-weight infants: the AGA suggests specific Lactobacillus and Bifidobacterium strains, alone or in named combinations.[9]
Notice what is missing. The guideline does not address healthy adults taking a daily probiotic for general gut wellness, because that is not one of the situations it covers.[9] And where it does suggest a probiotic, it names exact strains rather than a general category. That matters because, as NCCIH explains, different probiotics may have different effects, and if one kind of Lactobacillus helps prevent an illness, that does not mean another kind would do the same.[10]
Why the strain on the label matters
Many probiotics are sold as dietary supplements, which do not require FDA approval before they are marketed.[10] Supplement labels may describe how a product affects the structure or function of the body without FDA approval, but they cannot claim to lower your risk of a disease without the FDA's consent.[10] NCCIH also notes that some probiotic products have been found to contain microbes other than those on the label.[10] Since NCCIH says different probiotics may have different effects, the strain on the label is the detail to check against the strains the AGA names.[9][10]
What two reviews summarized by NCCIH found
Antibiotic-associated diarrhea is one example. NCCIH summarizes a 2017 review of 17 studies in people who were not hospitalized, in which taking probiotics alongside antibiotics was associated with about half the likelihood of antibiotic-associated diarrhea, although the reviewers called that conclusion tentative because study quality was only moderate.[10] For IBS, NCCIH describes a 2018 review of 53 studies that found possible benefits for overall symptoms and pain, but no definite conclusions and no way to say which strains help most.[10] The AGA, for its part, recommends probiotics for IBS only in the context of a clinical trial.[9]
Safety deserves a sentence too. NCCIH describes an extensive history of apparently safe use in healthy people, while noting that few studies have looked closely at side effects and that the risk of harm is greater in people with severe illnesses or compromised immune systems.[10] Our gut health page describes how we approach this: probiotics only when there is a specific reason, as a time-limited trial with a clear sign of whether it is working. A customized supplements plan is built from your labs, your diet, your medications, and your goals.
What the evidence backs
More fiber added gradually, fermented foods you enjoy, regular activity, and enough sleep. When a probiotic is used, a named strain chosen for a specific purpose, such as during antibiotics, as a time-limited trial.
Where caution is needed
A daily multi-strain capsule bought for general wellness, judged by its strain count or CFU number, or using home habits to put off an evaluation when there is bleeding, unplanned weight loss, or a lasting change in bowel habits.
Section 07 / Your first month
Where should you start if you live in Mount Pleasant or Charleston?
One way to pace the habits above is a four-week ramp, borrowing the gradual approach NIDDK advises for fiber and the 4-week ramp the Stanford study used.[1][4] Each step points to its source:
Week 1: Track what you eat for three days and add up your fiber. Add one fiber food a day and a glass of water with it.[1]
Week 2: Add a second fiber food and one daily serving of a fermented food you enjoy, such as plain yogurt or kefir.[1][4]
Week 3: Set a fixed wake-up time, seven days a week, and put screens away 30 minutes before bed.[7]
Week 4: Build toward 150 minutes of brisk walking or other moderate activity across the week, and count the different plants you ate.[3][8]
After a month, check in with yourself. Are bowel movements more regular? Is bloating better, the same, or worse? If nothing has changed, or if a food change made you feel clearly worse, write that down and bring it to your visit.
If you have warning signs, our post on gut signs that need attention explains which ones federal health agencies list and when to seek care. Colorectal cancer screening follows its own schedule, and checking the screenings you are due for is part of a primary care visit with Ashley.
When you want a plan built around your own symptoms, labs, and medicines, Ashley Harwyn, PA-C, sees patients at our Mount Pleasant office on Bramson Court and at The Longevity Club on Rutledge Avenue in downtown Charleston. If you have tried diets on your own without luck, our post on why nutritional therapy works better than diets explains the coaching side. You can book online or call when you are ready.
Gut Health Care
To sort out what is driving your symptoms and which tests are worth doing. Read Gut Health Care.
Nutritional Therapy
For weekly coaching on food changes such as adding fiber and fermented foods. Read Nutritional Therapy.
Customized Supplements
To decide whether a probiotic or fiber supplement fits your goals, and which one. Read Customized Supplements.
Founder, Solcara Health · Diplomate, American Board of Anti-Aging Health Practitioners (ABAAHP)
Ashley has practiced medicine for more than fifteen years. Her path into it began at home, with a family member born with a congenital heart defect and a childhood spent watching how much the quality of a clinician's attention could change the shape of a life. She has since practiced across a range of settings, including medical mission work in Uganda, before founding Solcara to build the kind of practice she kept wishing existed, one that treats patients as whole people and tells them the truth about what the evidence does and does not support.
NIDDK guidance on fiber and constipation, a Lancet series of systematic reviews on fiber, the American Gut citizen science study, randomized and controlled studies on fermented foods and exercise, a sleep and microbiome study, CDC sleep guidance, the federal Physical Activity Guidelines, the 2020 AGA probiotic guideline, and the NCCIH probiotics fact sheet, each accessed October 5, 2026.
National Institute of Diabetes and Digestive and Kidney Diseases. Eating, Diet, and Nutrition for Constipation. NIH. niddk.nih.gov
Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. 2019. pubmed.ncbi.nlm.nih.gov
McDonald D, Hyde E, Debelius JW, et al. American Gut: an Open Platform for Citizen Science Microbiome Research. mSystems. 2018. pmc.ncbi.nlm.nih.gov
Wastyk HC, Fragiadakis GK, Perelman D, et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021. pubmed.ncbi.nlm.nih.gov
Allen JM, Mailing LJ, Niemiro GM, et al. Exercise Alters Gut Microbiota Composition and Function in Lean and Obese Humans. Medicine and Science in Sports and Exercise. 2018. pubmed.ncbi.nlm.nih.gov
Smith RP, Easson C, Lyle SM, et al. Gut microbiome diversity is associated with sleep physiology in humans. PLoS One. 2019. pmc.ncbi.nlm.nih.gov
Centers for Disease Control and Prevention. About Sleep. CDC. cdc.gov
Office of Disease Prevention and Health Promotion. Top 10 Things to Know About the Second Edition of the Physical Activity Guidelines for Americans. US Department of Health and Human Services. odphp.health.gov
Su GL, Ko CW, Bercik P, et al. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. American Gastroenterological Association (Gastroenterology). 2020. gastro.org
National Center for Complementary and Integrative Health. Probiotics: What You Need To Know. NIH. nccih.nih.gov
Medical Disclaimer: This page is for educational and informational purposes only and does not constitute medical advice, and reading it does not create a patient-provider relationship. It describes general medical information and categories of care, not a recommendation that any individual start, stop, or change any test, treatment, or medication. Any diagnosis or treatment decision requires evaluation by a qualified, licensed clinician who knows your personal and family history. Consult a qualified healthcare provider before making medical decisions. Information reflects sources available as of October 5, 2026.
Ashley Harwyn, PA-C, ABAAHP, is a Diplomate of the American Board of Anti-Aging Health Practitioners (ABAAHP) through A4M and the founder of Solcara Health. Solcara serves South Carolina from Downtown Charleston (163 Rutledge Ave, Ste 202, The Longevity Club) and Mt. Pleasant (496 Bramson Ct, Ste 120).
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Ashley Harwyn, PA-C
PA-C, ABAAHP · Founder, Solcara Health
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