A study conducted in western India has examined whether drinking reverse osmosis (RO) water may be associated with vitamin B12 deficiency. The findings have drawn attention because a higher proportion of participants who reported using RO water had low B12 levels compared with those who obtained drinking water from other sources. However, the study does not establish that RO water itself causes vitamin B12 deficiency, and that distinction is important when interpreting the results.
The research involved 250 participants, with vitamin B12 deficiency identified in 70 people, representing 28% of the study group. The findings point to an association that researchers said warranted further investigation rather than providing evidence of a direct cause-and-effect relationship.
What did the study find?
Among the participants, 79 reported using RO water as their drinking-water source. Of this group, 40 people, or 50.6%, were found to have vitamin B12 deficiency.
By comparison, 171 participants used water from sources other than RO systems. Vitamin B12 deficiency was identified in 30 of them, equivalent to 17.5%.
The statistical analysis reported an independent association between RO water use and vitamin B12 deficiency. In simple terms, the two factors were found to occur together in the study population even after the researchers considered selected characteristics of the participants.
That finding, however, should not be interpreted as evidence that people who drink RO water will necessarily develop a vitamin B12 deficiency.
Why the results do not prove a direct cause
The design of the research is an important part of understanding its findings. It was a cross-sectional study, meaning information about participants and their health status was assessed at a particular point in time.
Such research can identify relationships between different factors, but it generally cannot establish which factor caused another. As a result, the findings cannot demonstrate that drinking RO water directly led to lower vitamin B12 levels.
This distinction is particularly relevant because vitamin B12 status can be influenced by several dietary and health-related factors. A single study showing an association should therefore be considered alongside evidence from other research before drawing broader conclusions.
Researchers considered diet and other factors
The study collected information on several characteristics that could potentially be relevant to vitamin B12 levels. These included participants’ sex, dietary habits, milk consumption, intake of dairy products and use of RO water.
People with already known causes of vitamin B12 deficiency were excluded from the research, according to the study information. Researchers then examined the available data to assess the relationship between water source and B12 status.
Even with these considerations, the study’s design limits how far its findings can be extended to the wider population. The results indicate an area for additional research rather than a recommendation for people to stop using RO systems.
Larger studies are needed
More research would be required to determine whether the reported association is reproducible and whether any biological mechanism could explain it. Future studies involving larger groups of people and longer follow-up periods could provide stronger evidence.
Researchers may also need to account for broader dietary patterns, lifestyle factors and other influences on vitamin B12 status. Until such evidence is available, it would not be scientifically appropriate to describe RO water as a confirmed cause of vitamin B12 deficiency.
For people concerned about low B12 levels, the appropriate approach is to consider their overall diet and health circumstances and discuss persistent concerns or suspected deficiency with a qualified healthcare professional.