It = Excessive alcohol ? Or gout?

The first mentioned subject in the passage is exceesive alcohol. The context reveals further references to alcohol and drinking.

It's = excessive alcohol consumption

Thanks.
And "the increase" refers to "risk increase"?

More context:
Alcohol consumption slightly reduces the risk of Type 2 diabetes, Willett says. Hensrud notes that moderate drinking is also linked to reduced risk of Alzheimer's disease.

Excessive alcohol consumption raises uric acid levels, which may predispose a person to gout. It's linked to cancers of the oral cavity, liver, stomach, breast (though, as I reported in November, the increase for moderate drinkers is modest), and colon and (among smokers who also drink) head and neck cancers. Drinking is tied to increased incidence of pancreatitis, gastritis and cirrhosis of the liver. Among very heavy drinkers, alcohol can interfere with the body's ability to absorb certain nutrients.

Though why anyone would pay attention I don't know. Between the scientists changing their minds so often about how specific food and beverage consumption reacts with the human body, and also all of the different do-gooders habitually being willing to say anything....true or untrue...to promote their version of clean living, statements such as in the OP are of dubious value.

I'll take what grandma told me 40 years ago about right eating and drinking before what I read or hear today.

Yes.