Most likely, the answer is yes, fibre is one of the missing links in your diet and this is what we’re going to explore in this article.
Nutritional research is often affected by region. This deviation is down to the fact that different areas eat different diets. For example, we’ve found in other articles that diets in developed countries can have levels of zinc higher than in developing countries.[1]
But this isn’t the case with fibre. It seems almost ubiquitously low across all regions, bar a few, and this makes this article appropriate wherever you’re reading this.
I find my prescriptions increasing dietary fibre equally as broad-ranging when helping people. The recommendation is the same, whether for digestive symptoms such as constipation, non-alcoholic fatty liver disease, weight management, blood sugar management or hormonal therapy. See what happens when you add another 10gms of dietary fibre daily.
But isn’t fibre a carbohydrate, and aren’t carbohydrates bad?
Yes, fibre is a carbohydrate and no, carbohydrates aren’t bad. But that’s a different article. Dietary fibre consists of non-digestible forms of carbohydrates that generally originate in plant-based foods.[2] In most cases, fibre isn’t absorbed in the small intestine but instead utilised in the large intestine and the colon via bacteria.[3]
The reduction in plant-based foods such as whole-grain foods, vegetables, fruits, legumes and nuts has driven the exposure of this vital macronutrient down, and in some places, the shortfall is surprising and concerning.
Dietary fibre intake is, on average, 40-60% below the recommended daily targets and increases your risk of major illnesses.[4]
These figures can generally be worse for children and older adults. In the UK, estimates suggest that people are getting around sixty per cent of their daily recommendations.[5] The United States estimates are around fifty per cent[6] , and Hong Kong maybe even less with average fruit and vegetable intakes around 1-2 a day over both genders.[7]
Interestingly, the omnipresent conditions around the world match the places where fibre content is lacking. This correlation is thanks to Denis Burkitt, who, when working in Uganda, noted that people between the ages of forty to sixty years had a lower incidence of diseases that were common in similarly aged people in England. These diseases included colon cancer, diverticulitis, appendicitis, hernias, varicose veins, diabetes, asthma and atherosclerosis. All of which connect to lifestyles commonly led in high-income countries.[8]
This connection became the origin of the Burkitt hypothesis, where Burkitt attributed the cause of these diseases to the lower quantity of fibre consumed. Post his death in 1993; numerous studies have confirmed Burkitt’s hypothesis.
A 2019 British Medical Journal review on several systematic reviews and meta-analyses (this is where they pool together studies of the same type and make more significant conclusions) found that eating more fibre reduced the risk of non-communicable disease and death.[9]
So there’s a pretty clear case that this form of currency for your body makes a real difference, but the two primary forms of fibre contribute in their way and point to one of the main reasons to have a diverse diet.
Soluble fibre has a prebiotic effect and can help to nourish the large intestine.[10]
Soluble fibre dissolves in water, and you can find it in the inner parts of the plants you eat.
Some of the primary sources of soluble fibre include fruits, oats, barley, legumes, peas, beans, vegetables such as broccoli and carrots and most root vegetables.[11]
This observation might be a personal opinion, but I think soluble fibre tends to have the most research to improve your health daily and long-term. Getting the best out of your diet is what this website category is all about.
“Is my diet enough” is about making sure the food you’re eating provides you with the resources to pay your body’s bills. Aside from your micronutrients, vitamins and minerals, having enough soluble fibre is crucial.
Soluble fibre can bind to cholesterol in the small intestine and prevent them from entering the body. This ability to bind to cholesterol gives soluble forms of fibre a cholesterol-lowering action that can contribute to preventing cardiovascular disease.[12]
A more detailed review of how soluble fibre can help with cholesterol levels had a consumption of a specific form of viscous-forming soluble fibre reducing total and low-density lipoprotein (LDL) levels by around five to ten per cent.[13]
Other studies, including this one, also confirmed that the increased soluble fibre intake did not affect high-density lipoproteins or HDL and triglycerides.[14]
On the metabolic front, that’s not all; soluble fibre affects how your carbohydrates are absorbed, positively affecting your insulin response.
This positive effect on insulin occurs because soluble fibre creates a slower drip-feed of the carbohydrates into the blood, meaning less insulin is required, stabilising the blood sugar after eating.[15] Something that can prevent slumps in energy similar to the typical 3 pm slump people see after lunch.
Building on this, soluble fibre can also help keep you full after eating, a clear bonus for weight management and portion control. One study found that increased soluble fibre intake can reduce body fat and waist-to-hip ratio. Over one month, the amount of soluble fibre used was ten to twenty grams daily (this is quite a considerable amount, so read on for some tips to get started).[16]
After reading all that, would you believe that the proportion of soluble to insoluble fibre in fibre containing foods is two thirds in favour of insoluble fibre![17]
Insoluble fibres can also help your metabolism and promote a healthier bowel pattern.[18]
An easy way to think of sources of insoluble fibre is that it’s in the outer skin of plants. So think skins of fruits from trees such as apples, bananas, avocado, many vegetables such as zucchini, green beans, celery, whole grains and nuts and seeds.[19]
Insoluble fibre is best known for its ability to bulk the stool and speed up the transit time of food through the gut. These fibres also hold a large quantity of water, leading to a stool softening effect that can help people with constipation.[20]
Insoluble fibre also helps your metabolism along with soluble fibre depending; it seems on the amount of fat in your diet. This assistance comes down to how insoluble fibre influences “metabolisable energy.”
Metabolisable energy is the total energy minus the energy lost in the stool, urine and gases. Another more well-known way of understanding this is energy in, energy out. Now, we’re far enough into research to know there are nuances to this for weight management, but it’s clear there is a significant connection to primarily weight gain.[21]
Insoluble fibre has improved metabolisable energy when animals consume a high-fat diet.[22]
While the how in this still needs to be confirmed in humans (remember, animal studies are only indicative of potential), insoluble fibre takes the energy with it out of the body. In a way, it makes the energy “indigestible” with it.
All prebiotics are dietary fibre, but not all dietary fibre is prebiotic.
If you’ve read other articles on nutrition as currency via this website, you might have come across a small piece I did on dietary fibre and its prebiotic role, and I’ll expand on it a little here.
A prebiotic is a “selectively fermented ingredient that allows specific changes, both in the composition and activity in the gastrointestinal microflora, that confer benefits.”[23]
The fundamental premise in this definition of soluble fibre as a prebiotic is that it is fermentable. This fermentation allows the soluble fibre to contribute energy to the colon, where the bulk of your probiotics is.
Forms of soluble fibre contribute to increased levels of Bifidobacterium[24] but also create critical compounds called “short-chain fatty acids.” These are also called “postbiotics.”
I could write a whole article on short-chain fatty acids. I’ll get there in time as they are so essential to get right for irritable bowel syndrome and other functional digestive disorders. As an introduction, short-chain fatty acids can improve leaky gut, glucose and lipid metabolism and regulate the immune system, inflammation and blood pressure.[25]
For this reason, we see prebiotic supplements becoming more popular in the over the counter market. Still, I would like to suggest that the only reason that this market exists is that people aren’t getting enough exposure to fibre in their diets. Hence, the question, is my diet enough?
I would say it is in the case of soluble fibre and its relation to your colonic and digestive health. There are deeper reasons to care about your fibre intake that are still in their infancy when it comes to research.
Fibre and cancer risk?
Now there is a caveat to this one. The results of studies around this still don’t seem to be consistent enough. But, indications are that fibre is associated with a reduced risk of colorectal cancer, breast cancer, and gastric and endometrial cancer.[26]
Further, a higher fibre intake positively affects breast cancer risk, with two meta-analyses showing an average of a ten per cent reduction in pre and post-menopausal breast cancer risk for women with higher fibre intakes.[27]
This study found that soluble fibre was more significantly associated with better outcomes[28] , but let’s be honest, eating more fruits and vegetables is a small price for these types of results.
But, what if, as a proportion of my patients offer, people find it difficult with work and life to prepare and eat that higher amount of dietary fibre.
This obstacle brings up an interesting conversation around the need to increase your fibre intake either via diet or supplementation.
There are numerous benefits to using fibre supplements, mainly soluble fibre based, for many conditions, and I’ll be compiling an article specifically around the best ingredients to use.
However, there is a trade-off between improving your diet and using a supplemental form. The first is the cost; adding more fruits and vegetables to your diet will most likely prove more financially sustainable.
Second, supplements generally have isolated fractions of soluble fibre researched to be of benefit. This specificity, of course, lends itself to potentially better therapeutic results in a clinical outcome, but not so much over time.
The reason why?
Simple, wrapped up in that plant-based source of soluble fibre is all the other nutrition that goes with it.
There are always two sides to this discussion and some definite context. For example, it’s always better to do something rather than nothing. So, start where you feel comfortable.
If you decide to supplement with fibre, start low and go slow.
When introducing a higher fibre content into your diet, especially in the case of supplementation, common symptoms can be gas, distension and even slower bowels. It’s essential to start the dose and work up to more significant quantities, once again, especially in the case of supplemental fibre.
Also, remember some of the things we have discussed in the article around insoluble fibre’s ability to draw water. This water drawing ability can lead to dehydration but also slower bowels. As always, the message is to increase your water intake and your increased dietary fibre content.
One of the best things about correcting macronutrient intakes such as fibre is multi-faceted benefits for your daily and long-term health.
So, what do you think?
As we touched on earlier, this website category is devoted to helping you find gaps in your diet where you might not be providing your body with enough resources to pay its bills.
The short-chain fatty acids produced by your fibre intake account for around ten per cent of the daily caloric requirements.[29] This percentage doesn’t consider the other things that short-chain fatty acids do around the body, which is another article entirely.
Prescribing higher fibre consumption to a patient can sometimes, even though I know the benefits, can feel like a bit of a benign offering. But time and time again, I see the results over a shorter time than you might think. Often in just a fortnight.
Why not assess how much fibre you’re getting over three days and see how close you are to the recommended thirty grams a day. You might just connect with one of the most typical blind spots in the western diet in 2022.
Hope this helps x
References
[1] Gupta S, Brazier AKM, Lowe NM. Zinc deficiency in low- and middle-income countries: prevalence and approaches for mitigation. J Hum Nutr Diet. 2020;33(5):624-643. doi:10.1111/jhn.12791
[2] Barber TM, Kabisch S, Pfeiffer AFH, Weickert MO. The Health Benefits of Dietary Fibre. Nutrients. 2020;12(10):3209. Published 2020 Oct 21. doi:10.3390/nu12103209
[3] O’Keefe SJ. The association between dietary fibre deficiency and high-income lifestyle-associated diseases: Burkitt’s hypothesis revisited. Lancet Gastroenterol Hepatol. 2019;4(12):984-996. doi:10.1016/S2468-1253(19)30257-2
[4] Mayor, Susan. (2019). Eating more fibre linked to reduced risk of non-communicable diseases and death, review finds. BMJ. 364. l159. 10.1136/bmj.l159.
[5] https://www.bda.uk.com/resource/fibre.html, viewed 31st March 2022
[6] Park Y, Hunter DJ, Spiegelman D, et al. Dietary fiber intake and risk of colorectal cancer: a pooled analysis of prospective cohort studies. JAMA. 2005;294(22):2849-2857. doi:10.1001/jama.294.22.2849
[7] https://www.chp.gov.hk/files/pdf/ncd_watch_april_2018.pdf, viewed 31st March 2022
[8] O’Keefe SJ. The association between dietary fibre deficiency and high-income lifestyle-associated diseases: Burkitt’s hypothesis revisited. Lancet Gastroenterol Hepatol. 2019;4(12):984-996. doi:10.1016/S2468-1253(19)30257-2
[9] Mayor, Susan. (2019). Eating more fibre linked to reduced risk of non-communicable diseases and death, review finds. BMJ. 364. l159. 10.1136/bmj.l159.
[10] Slavin J, Savarino V, Paredes-Diaz A, Fotopoulos G. A Review of the Role of Soluble Fiber in Health with Specific Reference to Wheat Dextrin. Journal of International Medical Research. February 2009:1-17. doi:10.1177/147323000903700101
[11] Akbar A, Shreenath AP. High Fiber Diet. [Updated 2021 May 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559033/
[12] Brown L, Rosner B, Willett WW, Sacks FM. Cholesterol-lowering effects of dietary fiber: a meta-analysis. Am J Clin Nutr. 1999;69(1):30-42. doi:10.1093/ajcn/69.1.30
[13] Surampudi P, Enkhmaa B, Anuurad E, Berglund L. Lipid Lowering with Soluble Dietary Fiber. Curr Atheroscler Rep. 2016;18(12):75. doi:10.1007/s11883-016-0624-z
[14] Surampudi P, Enkhmaa B, Anuurad E, Berglund L. Lipid Lowering with Soluble Dietary Fiber. Curr Atheroscler Rep. 2016;18(12):75. doi:10.1007/s11883-016-0624-z
[15] Garcia AL, Otto B, Reich SC, et al. Arabinoxylan consumption decreases postprandial serum glucose, serum insulin and plasma total ghrelin response in subjects with impaired glucose tolerance. Eur J Clin Nutr. 2007;61(3):334-341. doi:10.1038/sj.ejcn.1602525
[16] Chen C, Zeng Y, Xu J, et al. Therapeutic effects of soluble dietary fiber consumption on type 2 diabetes mellitus. Exp Ther Med. 2016;12(2):1232-1242. doi:10.3892/etm.2016.3377
[17] Wong JM, Jenkins DJ. Carbohydrate digestibility and metabolic effects. J Nutr. 2007;137(11 Suppl):2539S-2546S. doi:10.1093/jn/137.11.2539S
[18] Akbar A, Shreenath AP. High Fiber Diet. [Updated 2021 May 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559033/
[19] Akbar A, Shreenath AP. High Fiber Diet. [Updated 2021 May 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559033/
[20] Slavin J. Fiber and prebiotics: mechanisms and health benefits. Nutrients. 2013;5(4):1417-1435. Published 2013 Apr 22. doi:10.3390/nu5041417
[21] Romieu I, Dossus L, Barquera S, et al. Energy balance and obesity: what are the main drivers?. Cancer Causes Control. 2017;28(3):247-258. doi:10.1007/s10552-017-0869-z
[22] Lattimer JM, Haub MD. Effects of dietary fiber and its components on metabolic health. Nutrients. 2010;2(12):1266-1289. doi:10.3390/nu2121266
[23] Gibson GR, Probert HM, Loo JV, Rastall RA, Roberfroid MB. Dietary modulation of the human colonic microbiota: updating the concept of prebiotics. Nutr Res Rev. 2004;17(2):259-275. doi:10.1079/NRR200479
[24] Holscher HD. Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut Microbes. 2017;8(2):172-184. doi:10.1080/19490976.2017.1290756
[25] Nogal A, Valdes AM, Menni C. The role of short-chain fatty acids in the interplay between gut microbiota and diet in cardio-metabolic health. Gut Microbes. 2021;13(1):1-24. doi:10.1080/19490976.2021.1897212
[26] Zheng, B., Shen, H., Han, H. et al. Dietary fiber intake and reduced risk of ovarian cancer: a meta-analysis. Nutr J 17, 99 (2018). https://doi.org/10.1186/s12937-018-0407-1
[27] Farvid MS, Spence ND, Holmes MD, Barnett JB. Fiber consumption and breast cancer incidence: A systematic review and meta-analysis of prospective studies. Cancer. 2020;126(13):3061-3075. doi:10.1002/cncr.32816
[28] Farvid MS, Spence ND, Holmes MD, Barnett JB. Fiber consumption and breast cancer incidence: A systematic review and meta-analysis of prospective studies. Cancer. 2020;126(13):3061-3075. doi:10.1002/cncr.32816
[29] den Besten G, van Eunen K, Groen AK, Venema K, Reijngoud DJ, Bakker BM. The role of short-chain fatty acids in the interplay between diet, gut microbiota, and host energy metabolism. J Lipid Res. 2013;54(9):2325-2340. doi:10.1194/jlr.R036012
