After the rise to power of Nazism (1933), Joel was increasingly discriminated against by the regional Nazi Party leaders, especially Julius Streicher.

Joel moved his company to Berlin in 1934, where he rented a factory site in Wedding and installed new packing machines.

As discrimination further increased (e.g., deliveries had to be marked with a "J" for Jude, or Jew), and Jewish firms became Aryanized, Joel was forced to sell his company in 1938 to Josef Neckermann.

He married and had two children; his son Billy Joel became a popular singer and songwriter, a highly successful musician.

In 1957, Helmut and his wife divorced and he returned to Europe, finally settling in England, where he married again and had a second son, Alexander Joel, who became a conductor.