Fibre

Dietary fibre can be described as the part of plant foods that we don’t digest or absorb, for example the skins and pips of fruits and vegetables, or the outer husks of cereal grains1.

Since the 1970’s, we’ve known that fibre is important for a healthy digestive system2, but more recently nutrition scientists have become interested in other benefits of a high fibre diet, including protection against heart disease, diabetes and some cancers3.  

Because we don’t digest or absorb fibre, it passes through to our large intestines, where it is fermented by the bacteria which live there. As part of this process, compounds known as ‘short chain fatty acids’ are produced, which play a role in protecting us against various diseases4.

What do we know about fibre and psoriasis?

To date, there isn’t much research looking at the relationship between dietary fibre and psoriasis, but it’s possible that fibre may influence psoriasis indirectly, via a number of positive effects that it has on the body. These include:

  • Regulating appetite, helping us to maintain a healthy body weight.
  • Reducing the risk of insulin resistance.
  • Lowering cholesterol and heart disease risk.
  • Reducing inflammation.
  • Removing waste products from the body5.

We know that people with psoriasis have a higher risk of developing heart disease, so eating more fibre may help by protecting against this risk 6.

Fibre may also help manage insulin resistance 7,8, a condition where the body doesn’t respond properly to the hormone insulin, which controls blood sugar levels. Studies have shown that people with psoriasis are more likely to be insulin resistant than healthy populations 9,10, so eating more fibre may benefit blood sugar control in people with psoriasis.

There’s also evidence to show that people who eat more fibre have lower levels of inflammation in their body11,12. Because psoriasis is an inflammatory condition that seems to get worse as inflammation in the body increases, eating more fibre may potentially benefit psoriasis severity.

What does the science say?

Currently there is very limited research looking at the relationship between fibre intake and psoriasis.

In a recent study from Italy13, men with and without psoriasis were asked to complete detailed 7-day food diaries, to allow researchers to look for patterns between what they ate and the presence or severity of psoriasis. The researchers found that the men with psoriasis ate less fibre than the healthy controls. They also found men with psoriasis who ate lots of simple carbohydrates (sugars) had higher psoriasis severity scores.

Other researchers have looked at the effects of increasing fibre intake as part of an overall dietary programme to improve psoriasis. In one case study of five patients with chronic plaque psoriasis5, a 6-month dietary programme (which included fibre supplements together with high intakes of fruit, vegetables, olive oil and a reduction in red meat and refined carbohydrates) improved psoriasis severity (PASI) scores from an average of 18.2 to 8.7. In this study, the researchers suggested that fibre might benefit psoriasis by helping to eliminate waste products from the body that could potentially trigger psoriasis.  

If we look outside of psoriasis, there is good evidence that eating more fibre intakes can lower risk of heart disease14. This is important because people with psoriasis have a greater risk of heart disease.

High fibre diets have also been shown to protect against insulin resistancewhich doctors believe is a type of pre-diabetes. Because the risk of insulin resistance seems to increase as psoriasis severity worsens, eating more fibre could help to protect against this.

There is also evidence that fibre can positively influence levels of inflammation in the body. In one study, a high fibre diet was linked with lower levels of pro-inflammatory compounds (known as IL-6 and TNF), which are found in high levels in active psoriasis15.

Are there any risks of eating lots of fibre?

Most of us don’t eat enough fibre, so eating too much is not normally a concern.

Eating lots of fibre can trigger cramping, gas, bloating, especially if you suddenly change from a low to a high fibre diet, so it’s best to increase your intake gradually. For people with irritable bowel syndrome or other digestive conditions like Crohn’s, some types of fibre may aggravate symptoms such as bloating, gas and diarrhoea.

How much fibre do I need to eat?  

We don’t know how much fibre is the right amount for people with psoriasis, but in the UK, it’s recommended that adults aim for 30 grams of fibre a day, based on the evidence which shows that a high fibre diet can protect against a wide range of diseases.  

To put this into perspective, an apple, a slice of wholemeal bread and a handful of almonds all contain around 2.5 grams of fibre. According to dietary surveys in the UK, the average adult manages around 18 grams of fibre a day – about half of what we should be aiming for.  

Learning points

  • Fibre is the part of plant foods that we don’t digest and absorb. Fibre is essential for healthy digestion, but it’s also been linked to a lower risk of heart disease, diabetes and some cancers.
  • Limited research shows people with psoriasis eat less fibre and more refined carbohydrates than healthy controls.
  • Eating more fibre may benefit psoriasis indirectly by lowering inflammation and protecting against conditions associated with psoriasis, such as insulin resistance and heart disease.

Sources

  1. DeVries JW. On defining dietary fibre. Proc. Nutr. Soc. 2003;62(1):37-43. doi:10.1079/PNS2002234.
  2. Schweizer, T. F, Edwards CA. Dietary Fibre — A Component of Food: Nutritional Function in Health and Disease.; 1992.
  3. Association AD. Position of the American Dietetic Association: Health Implications of Dietary Fiber. J. Am. Diet. Assoc. 2008;108(10):1716-1731. doi:10.1016/j.jada.2008.08.007.
  4. den Besten G, van Eunen K, Groen AK, Venema K, Reijngoud D-J, 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.
  5. Brown AC, Hairfield M, Richards DG, McMillin DL, Mein E a, Nelson CD. Medical nutrition therapy as a potential complementary treatment for psoriasis–five case reports. Altern. Med. Rev. 2004;9(3):297-307. Available at: http://www.altmedrev.com/publications/9/3/297.pdf.
  6. Katta R DS. Diet and dermatology. The Role of Dietary Intervention in Skin Disease. J. Clin. Aesthet. Dermatol. 2014;7(7):46-51. doi:10.1136/bmj.298.6676.770.
  7. Lau C, Færch K, Glümer C, et al. Dietary glycemic index, glycemic load, fiber, simple sugars, and insulin resistance: The Inter99 study. Diabetes Care 2005;28(6):1397-1403. doi:10.2337/diacare.28.6.1397.
  8. Breneman CB, Tucker L. Dietary fibre consumption and insulin resistance – the role of body fat and physical activity. Br. J. Nutr. 2013;110(2):375-83. doi:10.1017/S0007114512004953.
  9. Gyldenløve M, Storgaard H, Holst JJ, Vilsbøll T, Knop FK, Skov L. Patients with psoriasis are insulin resistant. J. Am. Acad. Dermatol. 2015;72(4):599-605. doi:10.1016/j.jaad.2015.01.004.
  10. Boehncke S, Thaci D, Beschmann H, et al. Psoriasis patients show signs of insulin resistance. Br. J. Dermatol. 2007;157(6):1249-1251. doi:10.1111/j.1365-2133.2007.08190.x.
  11. Ma Y, H??bert JR, Li W, et al. Association between dietary fiber and markers of systemic inflammation in the Women’s Health Initiative Observational Study. Nutrition 2008;24(10):941-949. doi:10.1016/j.nut.2008.04.005.
  12. Krishnamurthy VMR, Wei G, Baird BC, et al. High dietary fiber intake is associated with decreased inflammation and all-cause mortality in patients with chronic kidney disease. Kidney Int. 2012;81(3):300-306. doi:10.1038/ki.2011.355.
  13. Barrea L, Macchia PE, Tarantino G, et al. Nutrition: a key environmental dietary factor in clinical severity and cardio-metabolic risk in psoriatic male patients evaluated by 7-day food-frequency questionnaire. J. Transl. Med. 2015;13:303. doi:10.1186/s12967-015-0658-y.
  14. Threapleton DE, Greenwood DC, Evans CEL, et al. Dietary fibre intake and risk of cardiovascular disease: systematic review and meta-analysis. BMJ 2013;347(dec19_2):f6879. doi:10.1136/bmj.f6879.
  15. Arican O, Aral M, Sasmaz S, Ciragil P. Serum levels of TNF-alpha, IFN-gamma, IL-6, IL-8, IL-12, IL-17, and IL-18 in patients with active psoriasis and correlation with disease severity. Mediators Inflamm. 2005;2005(5):273-9. doi:10.1155/MI.2005.273.
  16. Slavin JL. Dietary fiber and body weight. Nutrition 2005;21(3):411-8. doi:10.1016/j.nut.2004.08.018.

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