1929: "Guinness is Good for You" Through much of the 20th century, doctors thought Guinness had medicinal properties. Even until the 1950s mothers in Irish hospitals were given Guinness after giving birth because of the high iron content.
1862: Guinness adopts the harp logo as its brand. Until the late 1920s Guinness relied on word of mouth to promote its product.. When sales began to decline in the 1930s, Guinness hired S.H. Benson, an ad agency from London. The agency, which later merged with Ogilvy & Mather, would produce some of the best-known campaigns in advertising history.
So it's no surprise that the Benson agency's simple tagline "Guinness is good for you" was a hit with consumers when it was introduced in 1929. The slogan remained the foundation of the brand for the next 40 years, until the advertising environment became a little more regulated.