How to Add Fibre to Your Diet

11 Sep 2007, Garnerville, New York, USA --- Assortment of High Fiber Foods --- Image by © Envision/Corbis

In the last post, we examined lack of dietary fibre as a common theme between various modern disease states.

In this post, we’re going to look at ways in which you can ensure your getting enough of this important nutrient.

This is important, because a low fibre intake isn’t necessarily confined to the standard Western diet.

Low-carb and very low calorie diets are also at risk, from the lack of high fibre carbohydrate containing foods, and from restriction of food choice generally.

“Paleo” dieters can also be at risk if they fall into the bracket of Paleo that take the meat and eggs part a bit too seriously and skimp on the non-starchy vegetables, fruit and starchy tubers.

Vegans and vegetarians may be the only population getting adequate fibre intake, assuming a well-structured vegan or vegetarian diet. Despite the healthful image, there are still many vegans or vegetarians who have a poor diet that amounts to the standard Western diet, sans meat.

The Secret Benefit of Emphasising Fibre

I define the health of a diet by its nutrient-density. Irrespective of what balance of animal and plant foods an individual chooses to obtain these nutrients, the aim is filling the diet with essential vitamins, minerals, amino acids and essential fatty acids.

The implication of trying to include more fibre in your diet is that you naturally shift to better food choices and away from empty calories.

This is the secret benefit of deliberately emphasising fibre.

You increase the overall quality of your diet, because you move away from nutrient-poor food choices (cereals, breads etc. – even if the box says “high in fibre”) to more nutrient-dense foods (oats, lentils, beans and legumes).

You’re also taking a preventative step to insure yourself against various modern diseases.

Is Diet Enough or Do You Need to Supplement?

The current recommendations for fibre intake are between 20g-35g per day, with the variation relative to calorie intake: for every 1,000kcal you eat, you should be getting 14g fibre. [1]

This can be a difficult target to hit depending on the type of diet you’re following, particularly if you’re diet is unnecessarily restrictive or exclusionary. It’s another situation where broader dietary choices are a positive.

For example, if you’re following a diet in which you’re excluding all starchy carbs, beans and legumes, then you’d have to obtain all of your fibre intake from fruit, green leafy veg, nuts and seeds: that can mean a huge volume of veg which can be difficult to get in before you’re stuffed to the gills.

Many people who are low carb also minimize fruit, so another means of adding fibre to the diet is marginalised.

Nuts and seeds are sources of dietary fat, so there would be a higher overall caloric load to the diet by trying to keep a high fibre intake through these food sources alone.

I’m not saying that you can’t meet your fibre requirements by eating veg exclusively, or by avoiding beans, legumes and certain high fibre starchy carbs like oats or potatoes. It just takes a level of effort and attention to detail that most people don’t want to pay to their diet.

This is why it can be tricky for people to get appropriate fibre in their diets, particularly if certain food sources of fibre are off limits to them.

Its also why doing an audit on your diet is important, to see where your level of fibre intake currently stands. You may be in need of filling a gap.

Covering Your Bases – Diet First

Most people should, however, be able to meet their fibre requirements through food. In this case, broadening dietary choices can really make life easier.

It bears stating here: unless you’re following a low-carb diet because you’re overweight, completely sedentary or have blood sugar problems (in which case a low carb diet is a valid, effective and proven strategy), there is no need to overly restrict carbohydrate in the diet, thereby limiting sources of fibre.

In terms of food choices, I like bang-for-your-buck foods. Lentils, beans and legumes are a double whammy as they’re high in protein and add an average of 8g fibre per 100g. A medium 150g apple would have 3-4g. An ounce (28g) of almonds (the highest fibre nut) would have 3g.

So without doubt the biggest bang for your buck in filling your fibre needs comes from lentils and legumes.

Let’s put those numbers into perspective for carbophobes. Taking the average recommended 2,000kcal per day diet as an example, at 14g fibre per 1,000kcals, the recommended level of fibre in the diet is 28g.

For the sake of this example we’ll consider low carb to be 150g per day of carbohydrate or lower in a 2,000kcal diet.

You could cover the 28g requirement for fibre by eating 300g lentils, providing 24g fibre, a medium sized apple and an ounce of almonds, altogether providing 31g fibre.

Bear in mind that this is excluding carbs from veg, which no one in their right mind should ever count (nor count calories from veg).

That 31g of fibre comes at a grand total of 85g total carbs per day. You can’t call that anything other than low carb.

And if you really want to get anal about the whole thing and just look at net carbs, i.e. usable carbs after subtracting fibre, then the grand sum is 54g carbs per day.

So the idea of avoiding fibre-dense carb sources in order to facilitate a low carb diet is just nonsense.

I’d be remiss to not mention oats. While not as fibre-dense as legumes at 7g fibre from 53g total carbs (per 80g serving), the beta-glucan found in the fibre of oats has consistently been shown to have strong cholesterol and blood sugar lowering effects. [2, 3]

The following is a list of 5 highest fibre commonly eaten foods by food group. All foods refer to cooked/edible state:

Legumes (per 100g) Vegetables (per 100g) Starches (per 100g) Fruit (per 100g) Nuts & Seeds (per 30g)
1: Navy beans – 11g 1: Artichokes – 9g 1: Oats – 11g 1: Avocado – 7g 1: Chia seeds – 11g
2: Kidney beans – 9g 2: Brussels sprouts – 4g 2: Baked potato with skin – 8g 2: Raspberries – 6g 2: Flaxseeds – 8g
3: Pinto beans – 9g 3: Beet greens – 4g 3: Sweet potato – 4g 3: Blackberries – 5g 3: Toasted sesame seeds – 4g
4: Black beans – 9g 4: Broccoli – 3g 4: Parsnips – 4g 4: Blueberries – 4g 4: Almonds – 3g
5: Lentils – 8g 5: Cauliflower – 3g 5: Squash – 4g 5: Apples – 2.4g 5: Hazelnuts – 3g

Covering Your Bases – Insurance Policy

There may be situations where you have specific reasons for following a diet that makes it difficult to meet your fibre needs through food. Blood sugar problems necessitating a low-carb diet, or you’re purposefully following a low-carb diet for weight loss, may mean you should consider supplementing to fill in the blanks.

The most researched fibre supplement is psyllium seed husks, which are an effective soluble fibre supplement that have efficacy in reducing blood glucose, improving fat distribution and increasing bacterial fermentation. [4, 5]

One tablespoon per day, about 6g, is a good starting point, taken with at least 300ml water in the evening.

Flaxseeds are another option, with benefits in reducing cholesterol levels and protecting arteries, and up to 50g per day can be consumed with no adverse effects [6]. This could be a positive for someone following a low-carb, high fat diet, as 50g would net around 14g fibre.

The lignans in flaxseeds have also demonstrated anti-carcinogenic and chemo-protective effects. [7]

Use milled flaxseed, and take two tablespoons, around 8g, in the evening, again with a minimum of 300ml water.

There are two other specific populations in whom supplementing with fibre can be of particular benefit: people with autoimmune conditions, and the obese.

In the case of autoimmune conditions, leaky gut is a primary issue, so fibre may be difficult to tolerate and the short-chain carbohydrates (FODMAP’s) found in prebiotic foods like leeks, asparagus, chicory, Jerusalem artichokes, garlic, onions, chicory, wheat and oats can aggravate gastrointestinal symptoms.

In autoimmunity, however, it is still important to find a means of stimulating the growth of Lactobacilli and Bifidobacterium strains of bacteria in order to address leaky gut, as these bacteria can prevent immune-mediated disruption of the intestinal lining, improve intestinal barrier function, and increase immune function. [8]

Resistant starch is the solution to providing a means of stimulating beneficial bacterial growth in this case, as it can be tolerated without gastrointestinal symptoms. [8]

Supplementing with resistant starch typically uses potato starch or green banana flour. For someone following an autoimmune dietary protocol in which grains, nuts, seeds and certain vegetables, including potatoes, have been eliminated from the diet, green banana flour would be used at the outset, about two tablespoons (30g) mixed into a smoothie (remember resistant starch shouldn’t be heated), providing about 3g resistant starch.

In the case of autoimmunity, slowly introducing potato starch would be beneficial, as autoimmune protocols are heavy on meat, and potato starch has been shown to ameliorate the potential negative impact of red meat on the colon. [9]

Start very small though, Chris Kresser recommends ¼ of a teaspoon to begin, increasing the dose once tolerated. If you don’t notice any adverse reaction, incrementally add another ¼ teaspoon to build up to 2 tablespoons (15g) per day.

The last population who can benefit from fibre supplementation are overweight and obese. There is an argument to be made in favour of supplementing even if there is an adequate fibre intake through diet alone. In one study, adding psyllium to a diet already high in fibre provided the greatest reduction in risk factors for metabolic syndrome in obese subjects, over a high fibre diet alone. [10]

So if weight is an issue, consuming a high fibre diet and supplementing looks like an effective dual strategy to significantly reduce weight, body fat, triglycerides and insulin levels. [10]

The Target Number

The average fibre intake in Western diets is 14g per day: use one, or a combination of the options here, to insure that your fibre intake gets to a beneficial level of a minimum of 25-30g per day.

You can do this irrespective of the type of diet you follow, and the one aspect that deserves special emphasis is prebiotic foods, given their importance to gut health and bacterial function: leeks, asparagus, chicory, Jerusalem artichokes, garlic, onions and oats are all prebiotic foods that will stimulate Lactobacilli and Bifidobacterium strains (just be careful if you have an autoimmune condition, or suspect FODMAP intolerance).

Try and meet your fibre needs through food: outside of the populations identified above, there’s no reason why you can’t. If you do fall into a population that would benefit from supplementing, then do, because modulating gut flora is fast emerging as the most effective means of healing the gut, losing weight, increasing immunity, and protecting against disease.

Ultimately, the secret benefit focusing on fibre intake are the positive consequences for your diet overall, including:

  • Increasing focus on and awareness of food quality;
  • Increasing satiety and calorie intake control;
  • Increasing nutrient density;
  • Better blood sugar management;
  • Better gut health;
  • Better immune function;
  • Disease prevention.

Looking at that list of benefits would almost make you think it’s all too good to be true. But every one of those positive consequences is evidence-based.

So check your current fibre intake, and establish your baseline.

Then add to it if its falling short and fill the gaps, either through adding more fibre-rich foods to your diet, or through supplementation if needed.


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References:

  1. Anderson JWBaird PDavis RH JrFerreri SKnudtson MKoraym AWaters VWilliams CL. Health benefits of dietary fiber. Nutr Rev. 2009 Apr;67(4):188-205. doi: 10.1111/j.1753-4887.2009.00189.x. Available at http://www.ncbi.nlm.nih.gov/pubmed/19335713
  2. Tosh SM. Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products. Eur J Clin Nutr. 2013 Apr;67(4):310-7. doi: 10.1038/ejcn.2013.25. Available at http://www.ncbi.nlm.nih.gov/pubmed/23422921
  3. Sadiq Butt MTahir-Nadeem MKhan MKShabir RButt MS. Oat: unique among the cereals. Eur J Nutr. 2008 Mar;47(2):68-79. doi: 10.1007/s00394-008-0698-7. Available at http://www.ncbi.nlm.nih.gov/pubmed/18301937
  4. de Bock MDerraik JGBrennan CMBiggs JBSmith GCCameron-Smith DWall CRCutfield WS. Psyllium supplementation in adolescents improves fat distribution & lipid profile: a randomized, participant-blinded, placebo-controlled, crossover trial. PLoS One. 2012;7(7):e41735. doi: 10.1371/journal.pone.0041735. Available at http://www.ncbi.nlm.nih.gov/pubmed/22848584
  5. Khossousi ABinns CWDhaliwal SSPal S. The acute effects of psyllium on postprandial lipaemia and thermogenesis in overweight and obese men. Br J Nutr. 2008 May;99(5):1068-75. Available at http://www.ncbi.nlm.nih.gov/pubmed/1800548
  6. Martinchik AN, Baturin AK, Zubtsov VV, Molofeev VIu. Nutritional value and functional properties of flaxseed. Voprosy Pitaniia, 2012;81(3):4-10. Available at http://www.ncbi.nlm.nih.gov/pubmed/22888664
  7. Singh KK, Mridula D, Rehal J, Barnwal P. Flaxseed: a potential source of food, feed and fiber. Critical Reviews in Food Science and Nutrition, 2011 Mar;51(3):210-22. doi: 10.1080/10408390903537241. Available at http://www.ncbi.nlm.nih.gov/pubmed/21390942
  8. Slavin J (2013). ‘Fiber and prebiotics: mechanisms and health benefits.’ Nutrients, [e-journal], Apr 22;5(4):1417-35. Available at http://www.ncbi.nlm.nih.gov/pubmed/23609775 (Accessed 20th July 2015)
  9. Paturi G1Nyanhanda TButts CAHerath TDMonro JAAnsell J. Effects of potato fiber and potato-resistant starch on biomarkers of colonic health in rats fed diets containing red meat. J Food Sci. 2012 Oct;77(10):H216-23. doi: 10.1111/j.1750-3841.2012.02911.x. Epub 2012 Sep 5. http://www.ncbi.nlm.nih.gov/pubmed/22950602
  10. Pal SKhossousi ABinns CDhaliwal SEllis V. The effect of a fibre supplement compared to a healthy diet on body composition, lipids, glucose, insulin and other metabolic syndrome risk factors in overweight and obese individuals. Br J Nutr. 2011 Jan;105(1):90-100. doi: 10.1017/S0007114510003132. Available at http://www.ncbi.nlm.nih.gov/pubmed/20727237