LOS ANGELES — If you don’t want to dumb down with age, vitamin D may be the meal ticket.

A boosted daily dosage of the vitamin over several months helped middle-aged rats navigate a difficult water maze better than their lower-dosed cohorts, according to a study published online Monday in the journal Proceedings of the National Academy of Sciences.

The supplement appears to boost the machinery that helps recycle and repackage signaling chemicals that help neurons communicate with one another in a part of the brain that is central to memory and learning.

“This process is like restocking shelves in grocery stores,” said study co-author Nada Porter, a biomedical pharmacologist at the University of Kentucky College of Medicine.

Neurons also are better able to receive and process those signals in ways that are connected with memory formation and retrieval, the study found.

The improvements in memory were associated with a level of a vitamin D metabolite that is about 50 percent higher than the one recommended by the Institute of Medicine to maintain healthy bones, but in line with what other experts recommend, according to Porter.

Medical science has been expanding its view of the vitamin’s role beyond bone structure, linking deficiencies to higher risks of cancer and other diseases, as well as to higher rates of cognitive decline in the elderly. But medical panels and researchers have questioned those studies and cast doubt on the value of vitamin D supplements.

The vast majority of the vitamin D in our bodies is created in the skin from a naturally occurring precursor molecule, with the help of UV light from the sun. Some foods, such as milk, are supplemented with the vitamin.

“Many factors influence vitamin D levels, and it’s best for individuals to consult with their doctors before undertaking a specific vitamin D regimen,” Porter said.