You shouldn't trust anyone, ever. The average health podcaster has no idea what they are talking about, yet they are quite confident in their (lack of) knowledge.

Probably easy for me to talk since I am a doctor, so I can smell the bullshit, but any person owes it to themselves to verify information. People should get comfortable using pubmed and get educated on how to verify medical information. 

1. Always search for RCTs and Systematic reviews of RCTs, observational studies CANNOT establish a causal link.

2. Always make sure to read the proposed effect size. If the RR of an observational study is 1.2, just ignore it and continue living your life (that's the correlation between LDL and heart disease btw). Anything under 2 is simply not worth your time.

3. Always check who funded and authored the study. I ignore any nutritional study, no matter its supposed quality, published by Loma Linda university because those people have a religious goal with promoting vegetarianism.

4. Don't trust any new drug studies, always wait for at least ~7years before taking any new drug seriously. 7 years is the average time it takes to recall a dangerous drug from the market.

5. Be very skeptical about large effect claims and surrogate markers. I don't care if a diabetic drug improves glycemic control if people die more frequently while taking it or if the mortality rate remains the same.

I recommend reading Malcolm Kendrick's book "Doctoring Data" and "Deadly Medicines and Organised Crime" by P. Gotzsche to learn more. 

It is essential for the person to understand that medical research and medicine in general has been completely corrupted by pharmaceutical companies and governmental regulators. It is better to assume deception while reading a research study than honesty.