Republican presidential hopeful Ted Cruz has taken a hit at gluten-free meals in the military, equating them with a culture of political correctness.

The Texan senator made the comments at a rally for service members on board the USS Yorktown in South Carolina.

During the rally, Mr Cruz lashed out at what he called a "culture of political correctness" in the Pentagon weakening the military.

"The last thing any commander should need to worry about is the grades he is getting from some plush-bottomed Pentagon bureaucrat for political correctness or social experiments — or providing gluten-free MREs," he said, referring to the military's ready-to-eat meals.

Celiac disease advocates have slammed Mr Cruz's comments.

According to the Celiac Disease Foundation, about 1 per cent of Americans have celiac disease, which it describes as an "autoimmune disorder ... where the ingestion of gluten leads to damage in the small intestine".

Alice Bast, president and chief executive of Beyond Celiac, said strict adherence to a gluten-free diet was the only treatment for the disease.

"Senator Cruz's remarks equating the need for gluten-free food options with 'political correctness or social experiments' propagate misinformation about celiac disease that is both harmful and disparaging to the celiac disease community," she said in a statement.

There are a number of positions in the US military which cannot accommodate people who have celiac disease, and a Department of Defence spokesman told Time the provision of gluten-free meals differed based on each military branch.

Mr Cruz is currently touring the state of South Carolina, where he is trying to win the support of hard-line military voters ahead of the South Carolina primary.

At the USS Yorktown rally, he promised to rebuild a "robust" military if he was elected, referencing a Ronald Reagan-style military policy.

"I am confident that if we put in the hard work we can, as Ronald Reagan did in the 1980s, rebuild our military so it will be so feared by our enemies and trusted by our allies that, God willing, we won't have to use it," Mr Cruz said.

"That is the essence of what President Reagan used to call 'peace through strength.'"