What are the physiological effects of wine?
It is undisputed that heavy alcohol consumption (of any variety) leads to many deleterious effects on health.

It has also been claimed, however, that low to moderate alcohol intake can in fact be protective against some medical conditions (in particular, cardiovascular and cerebrovascular events). That is, there is often said to be a 'j-shaped' curve relating alcohol consumption to mortality and morbidity: low to moderate intake actually slightly reduces risk of adverse events relative to people who abstain completely from alcohol, but the risk increases markedly as consumption becomes heavy. See Plunk et al (2014): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3872245/ 

Sometimes the protective association is attributed to the alcohol content itself (i.e. the ethanol), and sometimes to non-alcohol compounds (often specifically those found in red wine). The existence of such a possible protective effect at moderate doses is not a controversial position but it is also not settled science as yet. You should make up your own mind by reading reviews and ideally meta-analyses in the area. As a starting point, this 2013 review by Chiva-Blanch et al. in the journal Alcohol &amp; Alcoholism has been well-cited by other researchers and is available to read in full here: https://academic.oup.com/alcalc/article/48/3/270/244770