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Do supplements make you constipated?

Clare 3 years ago

Do supplements make you constipated?

Poor digestive health usually occurs as the result of a variety of different factors: diet, lifestyle, medications, and even supplements. Supplements, I hear you say? I thought all natural supplements were supposed to make you healthy?

Well, used in an appropriate manner, and at the right dosage, natural supplements may help to support our health, but it’s worth remembering that taking high doses of certain vitamin and mineral supplements may affect our bowel habits and make us constipated.

The following is not an exhaustive list, but just explains a little more about how some supplements may be causing constipation without us realising it. In a recent survey of 10,000 people conducted by Consumer Labs1, it was interesting that two of the most commonly-used vitamin and mineral supplements feature in the following list of constipation-causing supplements: calcium and vitamin D. 


Because of its association with healthy bones and teeth, calcium is one of the most widely-used mineral supplements, but taking higher doses is known to result in constipation symptoms2.

Why does this happen?

Well, in simplistic terms, calcium causes muscles to contract and this can affect peristalsis, the wave-like muscle contractions that help to move our foods through the digestive system. Magnesium helps muscles to relax, and the two minerals need to be in balance to facilitate stool transit, because each compete for absorption and so each affects the way the other works.  I always recommend that if you’re going to supplement with calcium, that you also take an equal amount of magnesium too. If you have a known calcium deficiency or other health issues, however, then you may need to take additional advice from a health professional regarding the best ratio for you to take.

It also depends on the type of calcium that you take, as not all formulas are the same, for example, taking calcium in the form of calcium citrate is less likely to have a constipating effect than calcium carbonate3. If you take calcium along with other supplements known to have a binding effect then you might need to think about supporting your bowel regularity with additional dietary fibre such as psyllium, though do make sure that you drink enough (see note below), or consider probiotic and prebiotic preparations that are specifically formulated to help with bowel regularity.

Spreading the doses of the supplements out across the day can also help to prevent constipation side effects, as can drinking plenty of water. Dietary sources are also less likely to cause constipation symptoms and are actually very easy to come by as calcium is a very ubiquitous mineral. You’ll find it in green leafy vegetables, dairy products, nuts, especially almonds, seeds, grains, tinned oily fish (preferably with bones), and soya products. 

Vitamin D

The best way of getting your vitamin D is to get outdoors! 

With the sun being in short supply in many areas of our beautiful planet, and with technology and busy lifestyles forcing us to stay indoors, vitamin D deficiency is on the increase. This vitamin is therefore another of the most widely-used supplements used by health-conscious individuals around the world.

Vitamin D's main function in the body is to aid calcium absorption, and so taking large doses can lead to higher calcium levels in the blood stream. So after reading about the effects of too much calcium, then it’s not difficult then to see why this very commonly-used supplement may contribute to slower stool transit.

Unless you are following professional advice or have a known deficiency, it’s sometimes better to supplement with a complex that contains a balanced combination of nutrients, rather than just taking one nutrient in large doses as it is also possible to overdose on vitamin D; however, daily doses of around 1000iu shouldn’t cause any problems.

While we are all aware of the risk of skin cancer from getting sunburned, and so need to be sensible when staying out in the sun for long periods of time, the best way of getting our vitamin D is still to get plenty of exposure to the sun, if you can find it! A natural feedback mechanism in our bodies helps to ensure that we don’t manufacture too much vitamin D in this way, so try to get a few minutes a day in the sun at least. Also don’t forget that vitamin D can be found in a few dietary sources too, such as oily fish, and eggs.


Some of our favourite supplements could be making us constipated 


Iron supplements are used mostly commonly by ladies, as menstruation can be a monthly drain on iron reserves in women, though declining stomach acid levels and other factors can also contribute to iron deficiency in both sexes. But taking oral iron supplements can cause digestive upsets and constipation4, as iron is not readily absorbed and a build-up of the metal in the bloodstream can result in constipation, as this will affect the performance of the muscles and nerves in the bowel.

The key to preventing constipation from iron supplement is to increase absorption. Including amount of vitamin C in your diet can enhance the absorption of iron in your body, and like calcium, some forms of iron are absorbed better than others. Many people find that liquid forms of iron are better tolerated and absorbed, though these are not usually available on prescription. Have a chat to your doctor or health professional about the options available.

Again, taking iron in dietary sources is also less likely to cause unpleasant side effects, and iron-rich foods include red meats, leafy dark green vegetables, seafood, pulses, nuts and seeds5.

At this point, it’s worth mentioning that ‘Heme’ iron, the type of iron that is found from animal products, is the form of iron most easily absorbed by the body. Non-heme iron is found in plant foods, though also in meat and eggs, so vegetarians may need to give consideration to this fact and ensure that they’re doing what they can to enhance digestion and absorption, such as taking a good probiotic.

Psyllium/ bran

If you supplement with fibre such as psyllium or bran, make sure you drink plenty of water

This is an odd one, as most people think that adding fibre to the diet is supposed to help with constipation symptoms. However, a recent study6 indicated that adding fibre to the diet of constipation sufferers actually worsened their condition. The study authors concluded that adding extra fibre to the intestines could actually make stools larger, more bulky and more difficult to pass. 

One factor that could certainly exacerbate this process would be to eat or supplement with lots of fibre, and then be inadequately hydrated. Research suggests that dietary fibre works better to alleviate constipation if taken with enough fluid7; without enough water, adding fibre to your diet could dry stools out and make them even more difficult to pass, or become impacted in the digestive system and actually cause constipation.

I’ve found that in practice, it is amazing how little people consider the importance of adequate hydration and how profoundly it affects the digestive process. So, whether you’re taking additional fibre supplements, or just ensure that your diet contains lots of fibre in the form of wholegrains, fruit and vegetables, then ensure that you’re drinking at least 6-8 glasses of water each day in addition to your other choice of drinks.

Diuretic herbs and supplements

This leads me nicely on to those types of herbs and supplements that may promote water loss, known as ‘diuretics’. Dehydration is known to be a causative factor in constipation8, so potentially, any supplement or herb that has a diuretic effect, or promotes urine loss, therefore, such as dandelion, or even green tea, could potentially have an effect on bowel regularity if taken to excess, as fluid is so crucial to the digestive process. Water-loss supplements are popular for those wishing to lose weight, but I'm not a great fan of using diuretics in this way without taking professional advice, as you can upset the delicate balance of electroytes in your body.


If you take supplements with a diuretic effect, they could cause constipation

S. boulardii

Probiotics can be a great way to balance the gut flora, but it’s important to use the correct strain of bacteria for your needs. If you have a tendency towards constipation, then choosing to take high doses of the probiotic yeast, Saccharomyces boulardii, could cause constipation in sensitive individuals. Whereas Bifidobacterium lactis BB-12 has been shown to specifically improve regularity9, so it’s really all about the strain when it comes to choosing the right probiotic, so make sure that you're choosing the right probiotic supplement for your current needs.

I always suggest using a very well-researched brand, and taking advice if necessary about dosage and duration.

Seek advice if you're not sure

All in all, though vitamin and mineral supplements are widely available to purchase over the counter, many of them can have side effects if used inappropriately. It’s often worthwhile, therefore, to seek advice from your doctor or a qualified healthcare practitioner before taking them, to ensure that the combination and dosage is right for your needs and you avoid unnecessary side effects like constipation.



1. Consumer Lab: (2016) Vitamin Supplement Survey, available online at: https://www.consumerlab.com/news/highlights_vitamin_supplements_survey/1_31_2013/

2. Calcium, Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed July 2016.

3. Garg G, et al, (2012), Vitamin D toxicity presenting as hypercalcemia and complete heart block: An interesting case report, Indian J Endocrinol Metab. Dec; 16(Suppl 2): S423-5. doi: 10.4103/2230-8210.104116.

Available online at:  http://www.ncbi.nlm.nih.gov/pubmed/23565451

4. Iron, Natural Medicines Comprehensive Database. http://www.naturaldatabase.com Accessed July 2016.

5. Andrews, C. & Storr, M. (2011), The pathophysiology of chronic constipation, Canadian Journal Gastroenterol., 2011 Oct; 25(Suppl B): 16B–21B. Available online: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206564/

 6. Ho KS, et al. (2012), Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms. World J Gastroenterol 2012; 18(33):4593-4596

7. Anti M., et al (1998), Water supplementation enhances the effect of high-fiber diet on stool frequency and laxative consumption in adult patients with functional constipation,  Hepatogastroenterology. 1998 May-Jun;45 (21):727-32.

8. Arnaud MJ, (2003), Mild dehydration: a risk factor of constipation?, Eur J Clin Nutr. 2003 Dec; 57 Suppl 2:S88-95.

9. Eskesen et al, (2015), Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial, Br J Nutr. 2015 Nov 28; 114(10):1638-46. doi: 10.1017/S0007114515003347. Epub 2015 Sep 18.

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