Because there is a lot of confusion concerning this subject and even many practitioners still recommend taking probiotics on an empty stomach, let’s try to find out what is the best time of the day to ingest them.
Since we know that the more acidic the stomach is the more harmful it can be for the probiotic bacteria, the answer to the above question is very simple – we should take probiotics when the stomach is less acidic.
Stomach acidity is described in terms of pH – the lower the pH in the stomach the higher the acidity, whereas higher pH means that the stomach is less acidic and more friendly for the probiotic bacteria.
Unfortunately, it is not a good idea to take probiotics on an empty stomach; due to the very low pH (stomach is more acidic) which makes the bacteria less likely to survive.
The average non-elderly adult has a fasting stomach pH (when the stomach is empty), in the range of 0.8–2. Food, however, acts as a buffer that neutralizes stomach acid. Therefore, a meal can raise pH to 4 or 5 (depending on the type of food consumed) which is much less acidic and closer to neutral (7). As a result, there is a much higher chance the probiotics will survive. Stomach pH 4-5 might not look like a big difference, but the pH scale is logarithmic and therefore 4 is 100 times less acidic than 2.
It is also important to remember that the older we get the less acidic the stomach pH can be. Therefore, some people may have close to neutral or neutral stomach pH (5–7).
Achlorhydria (deficiency of hydrochloric acid causing neutral pH) can be the result of using proton-pump inhibitors prescribed to treat acid reflux.
Of course, stomach acidity during the meal can be influenced also by the type of food we consume as unrefined plant foods are mostly alkaline while high-protein animal foods (meat, dairy, eggs, fish, etc.) and some stimulants such as coffee are acidic or very acidic. In addition, unrefined plant foods contain fibre which probiotics feed on in the intestines and therefore it also helps them to thrive in the gut.
Researchers found that probiotics taken shortly before or at the beginning of a meal, survived in much higher numbers than if taken 30 minutes after a meal (>). In addition, they also discovered that probiotics taken with food containing healthy fats (seeds, nuts, avocado, olives, cold-pressed olive oil, raw coconut oil, flax oil, etc.) had the greatest survival rates.
It is also important to keep in mind that after leaving the stomach, probiotics have to cope with intestinal acidity. And, that is another reason to ingest them with a meal (especially fatty unrefined plant foods) as it makes also intestines less acidic helping the bacteria to survive.
In addition, when bacteria travel through the intestines mixed with healthy food then also the bile and pancreatic enzymes increase the intestinal pH making the environment more alkaline and friendly for probiotics that are able to multiply and recolonise the small intestine where they can make absorbable vitamin B12 and other B vitamins, various enzymes such as lactase and protect intestinal walls. It is very beneficial for our health to help probiotics to colonise at the border between small and large intestines because the fat-soluble vitamins (A, C, D, E, & K) are absorbed there and digestive enzymes are recycled.
Written by Slawomir Gromadzki, MPH
Tompkins TA, Mainville I, Arcand Y. The impact of meals on a probiotic during transit through a model of the human upper gastrointestinal tract. Beneficial Microbes. 2011 Dec 1;2(4):295-303. (https://pubmed.ncbi.nlm.nih.gov/22146689/)