According to a biostatistitian. Nothing new for hardcore biohackers here, who do their own research, but a good reminder for the more casual folks.
How to do your own online health research like a scientist – a biostatistician’s step‑by‑step guide
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If we do this, ignoring the fact some studies are fraudulent, we’re better off by using the evidence table explicitly or implicitly, than otherwise and going through the evidence hiearchy for a question – excellent.
Suppose I’m interested in helping my pregnant sister understand whether taking fish oil, which contain omega-3 fatty acids – specifically DHA – during pregnancy will help lower her chances of having a preterm birth.
We can put these variables in what I call an evidence table.
The Question Exposure DHA Outcome Preterm birth Population Pregnant women Time Frame Duration of pregnancy Laying out the variables this way helps you be precise about exactly what question you’re asking. It will also help make sure the studies you draw on actually match these variables.
In the case of the question on how taking fish oil – specifically DHA – affects pregnancy, I might start by searching for something like “DHA preterm birth systematic review” in PubMed. When I did this in July 2026, I got 23 results.
The top result was a systematic review published in 2020 titled “Risk factors for postpartum depression: An evidence-based systematic review of systematic reviews and meta-analyses.” This might be a good place to start if I were interested in assessing the effects of DHA on postpartum depression, but the outcome I am interested in is preterm birth.
To double-check my assessment, I can add these components to my evidence table. There is a mismatch between my question and the evidence provided in this study. This is one of the most important factors to consider when deciding whether a study will be helpful: Does the evidence match your question of interest?
The Question The Evidence Exposure DHA fish and PUFA intake Outcome Preterm birth Postpartum depression Population Pregnant women Pregnant women Time Frame Duration of pregnancy Duration of pregnancy The second result in my PubMed search was titled “Omega-3 fatty acid addition during pregnancy.” It was published in the Cochrane Library, which is a top publisher of systematic reviews. Reading through this article, I see that the exposure (a combination of DHA and another omega-3 fatty acid called EPA), study population (pregnant women) and outcome (preterm birth) match what I am interested in.
The Question The Evidence Exposure DHA DHA and EPA Outcome Preterm birth Preterm birth Population Pregnant women Pregnant women Time Frame Duration of pregnancy Duration of pregnancy The results suggest that the incidence of preterm birth was lower among women who took DHA and EPA compared to those who didn’t.
Excellent. I tell my sister that taking DHA could be a good idea.