This purports to be a meta-study, not an experiment in itself. I observe that all but one of the authors come from the sports departments at their respective universities.
Our findings indicate that drinking HRW can significantly improve lipid status in the clinical populations.
You might think, reading that, that "significantly" means "by a substantial amount". That's what people usually mean by that wording. That is not the sentence you write if you mean that a result is statistically significant, which is what they actually mean. In fact the effect they report is not a "significant[] improvement" at all in the usual understanding of that. The average size effect is small. Moreover there is great diversity in the size effects across the studies, indeed even the sign (plus or minus) is pretty random. What they actually should have written is that the average size effect is small, but its difference from zero is
statistically significant. This is a common feature of statistical studies attempting to show that woo is true - you get an effect which is small and statistically different from zero. It is a fair description of a result which is not worth the paper it is written on.
I was entertained by these sentences.
In terms of intake, all participants in the studies ingested HRW.
...
The PEDro scale mean score for the included studies was 9.28, considered as excellent quality.
In other words, none of the studies they looked were RCTs, none had control groups, and none were blinded in any way. I don't know what this PEDro scale for study quality is. But a scale which rates experimental studies of a treatment with these well known design deficiencies as very high quality is evidently not an appropriate metric for this type of study. There should be no ethical problems with proper RCT methodology here.