Niacin, also known as vitamin B3, is a water-soluble vitamin that plays a crucial role in energy metabolism and the maintenance of healthy skin, nerves, and digestion [2]. Alcohol consumption can lead to niacin deficiency, as it impairs the absorption, storage, and metabolism of the vitamin [3].

According to Drug Patent Watch [1], alcohol itself does not directly reduce niacin's effectiveness. However, chronic alcohol consumption can lead to liver damage, which in turn can impair the body's ability to convert tryptophan into niacin. This can result in niacin deficiency and its associated health problems.

The Office of Dietary Supplements at the National Institutes of Health [2] states that heavy alcohol consumption can reduce the body's ability to absorb and utilize niacin. Alcohol also increases the excretion of niacin from the body, further reducing its effectiveness. Moreover, alcohol can interfere with the enzyme that converts tryptophan into niacin, leading to niacin deficiency.

A study published in the Journal of Clinical Medicine Research [3] found that chronic alcohol consumption can lead to niacin deficiency and its associated health problems, such as pellagra, a condition characterized by skin rashes, diarrhea, and mental confusion. The study also found that alcoholics who were given niacin supplements showed improvements in their symptoms.

In conclusion, alcohol consumption can reduce the effectiveness of niacin by impairing its absorption, storage, and metabolism, and by interfering with the conversion of tryptophan into niacin. Chronic alcohol consumption can lead to niacin deficiency and its associated health problems. It is recommended that individuals who consume alcohol regularly should ensure that they are getting enough niacin in their diet or through supplements [2].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ALCOHOL
[2] https://ods.od.nih.gov/factsheets/Niacin-HealthProfessional/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772032/