Is Fiber Really Essential?

[Systemlord]

The key things people say about the carnivore diet is you get nutritional deficiencies. Theoretically a carnivore diet theoretically does provide all essential nutrients. You can’t say that of any plant food. There’s not a plant food on earth that provides all essential nutrients. Animal foods can, seafood, red meat, poultry, eggs are missing a couple of nutrients and milk is missing even more, but meat, seafood, and poultry contain all essential nutrients we need.

What about fiber? Well fiber isn’t a nutrient. Could you last on a true carnivore diet without getting some kind of gut microbiome issue, because you need fiber right? Why do you need fiber? I thought you needed it. What does it do? A lot of people tell us that it prevents glucose from going into the bloodstream. Where’s the glucose coming from? The bloodstream. So you don’t need fiber? People who are paying close attention to nutrition science have a lot of half truths and beliefs about food. If you’re eating a high carbohydrate diet, fiber can soften your glucose spikes and that’s a plus. But there’s a more effective way to lower your glucose spikes and that is to not get a glucose spikes in the first place.

Another thing people often say about fiber is that it sweeps your colon clean of toxins and there’s never been a study that demonstrates that. It’s really just a belief. The intestines clean themselves and the lining shed regularly, actually very frequently. The biggest myth about fiber is that it’s good for digestion because fiber by definition is indigestible. Isn’t fiber an essential for feeding bacteria, gut bacteria, and promoting regular bowel movements? There’s quite a few papers on this claiming that we need fiber because we need to feed ourselves butyrate which breaks down fiber. Butyrate if you think about what a ketone is, it’s beta hydroxy butyrate which feeds the intestinal cells as well and therefore you don’t need fiber.

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[FunkOdyssey]

Is Fiber Really Essential?​

No, absolutely not:

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[Systemlord]

Thanks for the link to the YouTube video @FunkOdyssey. Too bad my video isn’t on YouTube.

There’s this young woman at work that has terrible facial acne. I’ve been meaning to tell her what might be causing it, fiber. I hear so many stories of women going on the carnivore diet and their lifelong acne goes away.

That acne is a warning, a message, trying to tell the you that they’re putting something in your body that shouldn’t be there, similar to an allergic reaction.

 

[Cataceous]

Grok to the rescue:

Direct Answer

• Research suggests a high-fiber diet likely improves health, with strong evidence for benefits like better digestion, heart health, and blood sugar control.
• The evidence leans toward reduced risks of heart disease, type 2 diabetes, and certain cancers, though some areas (like cancer prevention) have mixed results.
• Most studies support whole food sources (fruits, veggies, grains) over supplements for maximum benefits.

Digestive and Gut Health
A high-fiber diet helps prevent constipation, supports regular bowel movements, and may reduce risks of hemorrhoids and diverticulitis. It also feeds beneficial gut bacteria, promoting a healthier microbiome.
Heart and Metabolic Health
Fiber, especially soluble types, can lower "bad" cholesterol and blood pressure, reducing heart disease risk. It also helps control blood sugar, potentially lowering type 2 diabetes risk.
Weight and Longevity
High-fiber foods are filling, aiding weight management, and studies suggest they may increase lifespan by reducing overall mortality risk.
For details, see Mayo Clinic on Fiber or Harvard Health on Fiber.

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Comprehensive Health Benefits Report
This report provides a detailed examination of the scientific evidence supporting the health benefits of a high-fiber diet, drawing from multiple reputable sources, including peer-reviewed studies, health organization websites, and recent research. It expands on the direct answer, offering a thorough analysis for readers seeking in-depth understanding.
Introduction
Dietary fiber, found in plant-based foods like fruits, vegetables, whole grains, legumes, nuts, and seeds, consists of non-digestible carbohydrates that play a crucial role in health. Over recent decades, research has increasingly highlighted its benefits, particularly in Western societies where fiber intake often falls below recommended levels. This report synthesizes findings from various studies to address the question of whether a high-fiber diet improves health, focusing on digestive, cardiovascular, metabolic, and longevity outcomes.
Health Benefits Overview
The evidence strongly supports that a high-fiber diet offers multiple health benefits, with consistent findings across systematic reviews, meta-analyses, and cohort studies. Below, we detail the key areas supported by scientific research, organized by health outcome.
Digestive Health
Fiber is essential for maintaining a healthy gastrointestinal tract. It increases stool weight and size, softening it and making it easier to pass, which helps prevent constipation. For individuals with loose stools, fiber absorbs excess water, adding bulk and reducing diarrhea-related dehydration.

• A 2024 article from Mayo Clinic on Fiber notes that fiber lowers the risk of hemorrhoids and diverticulitis (inflamed pouches in the colon) by promoting regular bowel movements.
• Fermented fiber feeds "good" gut bacteria, potentially reducing the risk of colon diseases by supporting a diverse microbiome, as mentioned in a 2023 StatPearls article.
• A 2022 Nutrition Source article emphasizes that high-fiber diets, particularly rich in whole grains, fruits, and vegetables, are associated with decreased risk of diverticular disease and complications.

Cardiovascular Health
High fiber intake, especially soluble fiber, is linked to improved heart health. Soluble fiber, found in foods like oats, beans, and certain fruits, binds to bile acids in the gut, reducing cholesterol absorption and lowering LDL ("bad") cholesterol levels. This process also helps reduce blood pressure and inflammation, key factors in cardiovascular disease.

• A 2023 EatingWell article cites a 2022 BMC Public Health study showing higher fiber intake reduces cardiovascular disease (CVD) risk, likely due to decreased lipid uptake and reduced inflammation.
• A 2023 [Advances in Nutrition review](referenced in EatingWell) suggests soluble fiber decreases cholesterol levels by interfering with lipid absorption in the intestinal tract.
• A 2022 NIH research matter found that certain fibers, like arabinoxylan, reduce cholesterol, supporting heart health, though effects vary by individual.
• Epidemiological studies, as noted in the Nutrition Source, show high dietary fiber intake is associated with lower risk of heart disease and cardiovascular deaths, with cereal fibers showing particular benefits.

Blood Sugar Control and Diabetes Prevention
Fiber, particularly soluble fiber, slows the absorption of sugar, helping to stabilize blood glucose levels. This is especially beneficial for individuals with diabetes and those at risk of developing type 2 diabetes.

• A 2020 PMC article reports that high-fiber diets improve insulin sensitivity, reduce HbA1c levels, and support metabolic health, with a systematic review and meta-analysis showing benefits in diabetes management.
• A 2023 [Journal of Diabetes Investigation study](referenced in EatingWell) found higher overall fiber intake, including both soluble and insoluble types, predicted greater prevention of type 2 diabetes, possibly due to favorable effects on blood glucose, gut microbiome, and inflammation.
• A Japanese cohort study (Morimoto et al., 2020, cited in PMC) showed that increasing the ratio of dietary fiber to carbohydrate intake reduced HbA1c, suggesting utility in preventing type 2 diabetes.
• A Mexican study on adolescents (cited in PMC) demonstrated that higher fiber intake lowered odds of insulin resistance, adjusted for confounders like body fat and saturated fat intake.

Weight Management
High-fiber foods are filling due to their bulk and lower energy density, which can help reduce appetite and prevent overeating, supporting weight loss and maintenance.

• Harvard Health (2024) notes that fiber helps you feel full longer, reducing the likelihood of overeating, and large studies show it aids weight management.
• A 2015 trial in Annals of Internal Medicine (referenced in the thinking trace) found that increasing fiber intake by 14g/day led to significant weight loss over 12 months without calorie restriction, supporting its role in weight control.
• The 2023 EatingWell article mentions a 2023 Frontiers in Nutrition study showing people who ate more fiber after weight loss weighed less, suggesting fiber helps maintain lower weight.

Cancer Risk Reduction
While the evidence is stronger for some cancers, particularly colorectal cancer, high fiber intake is associated with reduced risk, likely due to faster waste transit and reduced exposure to carcinogens.

• A 2018 [World Cancer Research Fund report](referenced in the thinking trace) found a 10–20% risk reduction per 10g/day of fiber intake for colorectal cancer, with stronger evidence for whole grains.
• Harvard Health notes mixed results in large studies, but increasing whole grain consumption, rich in fiber, is associated with decreased colorectal cancer risk.
• However, Healthline (2023) cautions that while studies associate high fiber intake with reduced colon cancer risk, correlation doesn’t equal causation, and no studies have confirmed direct cancer-preventive effects, indicating some controversy.

Longevity and Mortality
Higher fiber intake is linked to increased lifespan, likely due to its combined effects on heart health, metabolic health, and reduced chronic disease risk.

• A 2015 American Journal of Epidemiology study (referenced in the thinking trace) linked high fiber intake (25–35g/day) to a 20–25% lower risk of all-cause mortality over 9 years, supporting longevity benefits.
• Mayo Clinic (2024) states that higher fiber intake is associated with lower risk of dying from any health condition, including heart disease, reinforcing this finding.

Fiber Types and Sources
Dietary fiber is categorized into soluble and insoluble types, each offering specific benefits. Soluble fiber dissolves in water, forming a gel-like substance, and is found in oats, beans, fruits, and vegetables. Insoluble fiber, found in whole grains, beans, and root vegetables, adds bulk and aids gut transit.

• A 2023 ScienceDirect article notes that dried beans, oat products, and certain fruits/vegetables are good sources of soluble fiber, while most plant foods, especially wheat bran, provide insoluble fiber.
• The Nutrition Source (2022) recommends a variety of fiber types from whole foods to ensure comprehensive health benefits, as each type offers some level of advantage.

Recommended Intake and Guidelines
Current guidelines advise higher fiber intake than most people consume. The National Academy of Medicine recommends:

Group	Recommended Daily Fiber (grams)
Women >50	21
Women ≤50	25
Men >50	30
Men ≤50	38

• However, StatPearls (2023) notes that the average U.S. intake is about 15g/day, only half the recommended amount, highlighting a significant gap.
• Medical News Today (2023) suggests introducing high-fiber foods gradually over weeks and drinking plenty of water to avoid bloating or dehydration.

Whole Foods vs. Supplements
While fiber supplements can provide some benefits, whole food sources are generally preferred for their additional nutrients and synergistic effects.

• A 2017 review in The Lancet (referenced in the thinking trace) found that dietary fiber from whole foods supports gut microbiota diversity more effectively than supplements.
• Medical News Today (2023) notes that supplements may provide fewer benefits than dietary fiber, emphasizing the importance of food sources.
• A 2022 NIH study found that purified fiber supplements decreased gut microbial diversity, suggesting whole foods are superior for microbiome health.

Caveats and Considerations
While the benefits are well-supported, there are caveats to consider. Rapidly increasing fiber intake can cause bloating or discomfort if not done gradually with adequate hydration. Some medical conditions may require monitoring fiber intake under professional supervision, as noted in Medical News Today (2023).

• High doses of certain fibers, like long-chain inulin, were associated with increased inflammation and potential liver damage in a few individuals in a 2022 NIH study, indicating individual variability in response.
• The evidence for cancer prevention, particularly beyond colorectal cancer, remains mixed, with some studies showing correlation but not causation, as noted in Healthline (2023).

Conclusion
The scientific evidence, drawn from recent studies and reputable sources, strongly supports that a high-fiber diet improves health across multiple domains, including digestion, heart health, blood sugar control, weight management, cancer risk reduction, and longevity. While some areas, like cancer prevention, have mixed results, the overall consensus leans toward significant benefits, particularly when fiber is obtained from whole food sources. This aligns with dietary guidelines recommending 25–38g/day, far above current average intakes, underscoring the need for increased fiber consumption for optimal health.
Key Citations

• Mayo Clinic Dietary Fiber Essential for Healthy Diet
• Harvard Health Foods High in Fiber Boost Health
• ScienceDirect Health Benefits Practical Aspects High-Fiber Diets
• NIH Health Benefits of Dietary Fibers Vary
• PMC Health Benefits of Dietary Fibre
• StatPearls High Fiber Diet Overview
• Nutrition Source Harvard Fiber Information
• EatingWell Ten Amazing Health Benefits Fiber
• Medical News Today Eating High Fiber Diet Benefits
• Healthline Why Is Fiber Good for You Crunchy Truth

 

[DixieWrecked]

I did carnivore for about 3 months and it was the most epic craps I have had my entire life. In a good way. Perfect. My stomach was also flatter and less inflamed.

I'm not doing carnivore anymore. Just a lower carb natural diet but I felt like carnivore was an awesome reset for me to reprogram my hunger cues and allowing my gut to heal. Essentially I have made it into an elimination diet.

 

[Seagal]

If “essential” means absolutely required in the same way as some amino acids or certain vitamins, then fiber isn’t considered "essential" in that strict biochemical sense because the body doesn’t require it to perform basic metabolic functions or synthesize essential compounds.

 

[Vince]

The key things people say about the carnivore diet is you get nutritional deficiencies. Theoretically a carnivore diet theoretically does provide all essential nutrients. You can’t say that of any plant food. There’s not a plant food on earth that provides all essential nutrients. Animal foods can, seafood, red meat, poultry, eggs are missing a couple of nutrients and milk is missing even more, but meat, seafood, and poultry contain all essential nutrients we need.

What about fiber? Well fiber isn’t a nutrient. Could you last on a true carnivore diet without getting some kind of gut microbiome issue, because you need fiber right? Why do you need fiber? I thought you needed it. What does it do? A lot of people tell us that it prevents glucose from going into the bloodstream. Where’s the glucose coming from? The bloodstream. So you don’t need fiber? People who are paying close attention to nutrition science have a lot of half truths and beliefs about food. If you’re eating a high carbohydrate diet, fiber can soften your glucose spikes and that’s a plus. But there’s a more effective way to lower your glucose spikes and that is to not get a glucose spikes in the first place.

Another thing people often say about fiber is that it sweeps your colon clean of toxins and there’s never been a study that demonstrates that. It’s really just a belief. The intestines clean themselves and the lining shed regularly, actually very frequently. The biggest myth about fiber is that it’s good for digestion because fiber by definition is indigestible. Isn’t fiber an essential for feeding bacteria, gut bacteria, and promoting regular bowel movements? There’s quite a few papers on this claiming that we need fiber because we need to feed ourselves butyrate which breaks down fiber. Butyrate if you think about what a ketone is, it’s beta hydroxy butyrate which feeds the intestinal cells as well and therefore you don’t need fiber.

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I believe the number one thing you need or we need. Healthy gut bacteria, probiotic and pre-probiotic. It works for me