Fiber vs. probiotics – how do they differ?

You are in the right place if you are looking for a comprehensive guide on fiber vs. probiotics. 

You may wonder if one is better than the other or if you can use fiber and probiotics together. 

In this blog, I give the lowdown on fiber vs. probiotics, including what fiber and probiotics are, how they affect the gut, and how they differ.

What are probiotics?

Probiotics are defined as live microorganisms (bacteria, yeast, spores, etc.) that, when administered, confer a health benefit (1). 

Probiotics are a hot topic at the moment, with research constantly emerging. 

Potential Benefits of probiotics include:

• Improvement in symptoms of digestive disorders (including IBS and inflammatory bowel disease). (2, 3)
• Improvement in mental health conditions (including depression, anxiety, and OCD) (4). 
• Improvement in skin conditions (including dermatitis, acne, and dandruff) (5).
• Improved immune defense against infections such as UTIs and respiratory infections( 6, 7). 

Prevention and treatment of antibiotic-associated diarrhea (8).

The exact mechanisms of probiotics remain unclear; however, changing the composition of our gut microbiota is likely linked to these potential health benefits (9). 

Probiotics increase the amount of ‘good’ bacteria and decrease the ‘bad’ bacteria in our gut (9). 

Probiotics come in multiple forms, including powders, capsules, sachets, and fermented food products.

Although you can find probiotics in fermented products such as sauerkraut, kimchi, and kombucha, the evidence remains unclear whether they benefit our health (10).

Most people don’t need a probiotic as a healthy, diverse diet rich in fruits, vegetables, and whole grains is sufficient to maintain good gut bacteria (11). 

However, if you are considering taking a probiotic for your general health, choose a specific strain that provides a health benefit that would be useful for you. 

If you are immunocompromised, probiotics may not be suitable for you – speak with a health professional for further advice. 

If you are looking for a probiotic for IBS, check out this article:  Probiotics for IBS.

What is fiber?

Fiber is a type of carbohydrate that our body cannot digest. It is a crucial component of a healthy diet and plays a significant role in our digestive health (12). 

Fiber ‘adds bulk’ to our poo, making it well-formed and easy to pass (13). 

Benefits of fiber include (14):

• Preventing constipation 
• Reduced risk of cardiovascular disease
• Reduced risk of colorectal (bowel) cancer
• Reduced risk of type 2 diabetes and obesity

Fiber sources include fruits, vegetables, whole grains, and legumes. You can also buy it in supplement form. 

For more information on fiber supplements, see our post, The best soluble fiber supplement according to a dietitian. 

There are no specific guidelines for how much fiber people with IBS should consume. Therefore, adults should aim for 30g of fiber daily, including those with IBS (15). 

Fiber can also be a prebiotic, not to be confused with a probiotic. A prebiotic feeds the good bacteria in our gut.

Some sources of prebiotics include asparagus, garlic, chicory, onion, and Jerusalem artichoke. They are also available in supplement form (16).

For information on prebiotics and IBS, see our article: Do prebiotic supplements help IBS?

Fiber vs. probiotics – are they the same?

No. As you can gather from the descriptions above, fiber and probiotics are very different and not the same.

Probiotics are live microorganisms that confer a health benefit and are available in supplement form (1).

In contrast, fiber is a non-digestible carbohydrate found naturally occurring in various foods in our diet (12). 

I have summarized fiber vs. probiotics in the table below:

Fiber	Probiotics
Non-digestible carbohydrate.Found in foods such as fruit, vegetables and wholegrains.Can be taken as a supplement.Needed by everyone to maintain a healthy digestive system.	Live microorganisms (most often bacteria)Can be found in fermented foods such as kimchi, kombucha and kefir. Usually taken in supplement form. May benefit those with a specific health condition.

Fiber vs. probiotics for constipation? 

Constipation is defined as having a bowel movement less than three times per week and/or having stool that is hard to pass, causing excessive straining (16). 

Using dietary and lifestyle strategies such as fiber and probiotics can be effective in helping to manage constipation. 

Fiber helps constipation by softening and adding bulk to your poo (13). 

Specific fiber sources have been proven in research to help with constipation.

These fiber sources include:

• Linseeds and flaxseeds
• Psyllium husk
• Kiwis
• Prunes
• Partially hydrolyzed guar gum

(16, 17, 18)

For more information on taking these supplements to improve constipation in IBS, see our article How does fiber affect IBS? 

An imbalance of gut bacteria can be a cause of constipation. Addressing this imbalance of gut bacteria with probiotics can help to improve bowel function (19).

Certain strains of bacteria have been proven in research to improve constipation:

• Bifidobacterium lactis BB-12®
• Bifidobacterium lactis HN019 
• Bifidobacterium lactis DN-173 010

(20, 21, 22)

Choosing a probiotic that contains the above strains may help to alleviate constipation. I suggest trialing a strain-specific probiotic for 4-12 weeks to see if it helps with your symptoms. 

For more information on constipation, see our article What is constipation and how can you treat it?

Can I take probiotics and fiber supplements together?

Yes, there is no reason you cannot take probiotics and fiber supplements together. 

However, research needs to look at the combined effects of probiotics and fiber supplements. 

I would recommend individually trialing fiber and probiotic supplements may be best to determine which may improve your symptoms.

Fiber vs. probiotics – which one is better?

Fiber is essential for a healthy digestive system and general health, whereas probiotics are not. 

Only some people will benefit from using a probiotic.

A probiotic is only beneficial if you target a specific health issue with a probiotic scientifically proven to help with that particular health issue. 

Probiotics also come with a hefty price tag, whereas fiber can be integrated into our diet easily without much added financial cost. 

Fiber is essential, and so could be considered the ‘better’ of the two.

Summary

Fiber and probiotics are very different, but both provide their advantages.

However, fiber should be prioritized over probiotics for digestive and general health, as fiber is a crucial component of a healthy diet. 

Probiotics may benefit certain health conditions by altering the bacteria in our gut. Although probiotics are a hot topic currently, the reality is that research is still emerging.

 It may be worth trialing a strain-specific probiotic for 4-12 weeks to see if it relieves symptoms. 

Note that some probiotics on the market do not have scientific backing, so do your research before investing.