Have you ever heard that carrots are good for your eyes, or that they can help you see in the dark?

It's true – carrots are rich in the compound beta carotene, which your body uses to make a form of vitamin A that helps your eyes adjust in the dark.

That's just one of the important links between Vitamin A and eye health. Vitamin A is critical for our ability to see, according to a recent report from the Defense Health Agency's Vision Center of Excellence in Falls Church, Virginia.

"There are many factors that affect your eyes and vision, including genetics and age," said Maria Viswanathan, ophthalmologist at the VCE. "Adequate amounts of Vitamin A can help prevent the development of night blindness and slow age-related decline in sight."

With low vitamin A levels, the eye is unable to send visual signals to the brain. This can result in night blindness as an initial symptom. "High doses of vitamin A supplementation can potentially prevent vision loss," according to the VCE.

Vitamin A supports more than just eye health. It is important for the function of the immune system and reproductive systems. It also contributes to healthy heart, lungs, kidneys, and other organs, according to the VCE.

Vitamin A also boosts the immune system by stimulating the production and activity of white blood cells. It's an antioxidant that can prevent or slow damage to cells.

Additionally, vitamin A has a role in preventing inflammation and can help prevent inflammatory conditions like acne.

But the human body cannot make vitamin A on its own, so we rely on the food we consume to help jump start the creation of vitamin A. The pigment beta carotene is a major driver of vitamin A production.

Beta carotene is found in many vegetables. It is the nutrient that gives yellow, orange, and red fruits and vegetables their color. That includes carrots, cantaloupes, apricots, sweet potatoes, mangoes, pumpkins, and papayas. Beta carotene is also found in green, leafy vegetables like spinach, kale, and collards (even though the color of those vegetables is determined by a different chemical known as chlorophyll).

Beta carotene is also necessary for proper bone growth and development.

In immune health, beta carotene plays a key role in maintaining our body's defenses. It also keeps male and female reproductive systems healthy. During pregnancy, it ensures embryos grow and develop normally.

How Much Vitamin A Do We Need?

"We should ensure that we have the right amount of vitamin A," said Viswanathan. "Too little or too much can have negative effects on your health."

However, the amount of vitamin A people need depends on their gender and age, according to the National Institutes of Health Office of Dietary Supplements. The average daily recommended amount for every individual is measured in micrograms of retinol activity equivalents, a metric known as RAE.

The NIH recommends adult females get 700 mcg RAE, while adult males should get 900 mcg RAE daily. Pregnant and breastfeeding women need 770 mcg RAE and 1,300 mcg RAE respectively, according to the NIH.

Although vitamin A deficiency is uncommon in the developed world, it can occur in individuals who have cystic fibrosis, pancreatic insufficiency, chronic liver disease, short bowel syndrome, Crohn's or celiac disease, giardiasis, chronic diarrhea, highly selective dieting, dysphagia, mental illness, or who are bariatric surgery recipients, according to the VCE report.

Premature infants also tend to have low levels of vitamin A in their first year.

A simple blood test will let your health care provider know if you're getting enough vitamin A. But, generally, consuming a diet rich in nutritious and varied fruits, vegetables, dairy, grains, and protein should meet your body's needs for vitamins and minerals for optimal health and readiness.

"Research is ongoing to evaluate the effects of vitamin A on prevention and/or treatment of various infectious diseases," said Dr. Cecilia Mikita, a staff allergist and immunologist at the Walter Reed National Military Medical Center in Bethesda, Maryland.

"Vitamin A plays an important role in both innate and adaptive immune responses, specifically the integrity of the skin barrier and regulation of the differentiation, maturation, and function of numerous immune cells," she said.

For more information, or if you're concerned about your vitamin A levels, talk to your health care provider.