A Carrot a Day Keeps the Ophthalmologist Away: Can Vitamin A Enhance Night Vision?

The Old Adage

A popular misconception, vitamin A has long been associated with the ability to see in the dark. It has been said that eating carrots, a rich source of beta-carotene, can enhance night vision.

The myth originated during the Battle of Britain as an attempt to hide newfound radar technology. In 1940, John Cunningham, the “top-scoring night fighter pilot” of the Royal Air Force, became the first pilot to implement radar to strike down an enemy aircraft. Nicknamed “Cats’ Eyes” for his record of 20 kills, Cunningham was known to have skilled night vision. The Royal Air Force, raring to keep their successful development of radar a secret, published a faux story in British newspapers attributing Cunningham’s extraordinary night vision to carrots. The fallacy gained popularity rather quickly – People began to grow carrots and eat them frequently to improve their vision when navigating through World War II blackouts.

And so, the myth of carrots enhancing night vision was born!

Carrot-induced supervision may be a great story to coax children into eating their vegetables (who wouldn’t want night vision superpowers?!), but is there any truth to this old wives’ tale?

The FActs 

As we age, it becomes more difficult to navigate in the dark. The aging eye undergoes a number of changes, directly affecting our ability to see. One of these changes is the size of our pupils. The size of our pupils is dependent upon the interworking muscles of the iris – the pigmented ring that displays eye color. The iris becomes less receptive over time, causing the pupils to shrink about 2 millimeters by the time we reach our golden years. Smaller pupils: less light! In dim lighting, this effect is similar to wearing sunglasses. Weaker muscles in the iris also make dark adaptation – the ability to see in the dark following bright light exposure – more challenging. This is due to a delayed response of the pupil, which constricts in brightness and dilates in darkness.

Cloudier lenses contribute to increased difficulty seeing in the dark by stiffening and losing transparency. Decreased ability to focus on close objects leads to a condition known as presbyopia, and cataracts may result from diminished light passing through the lens. Aligning the back of your eyes is a membrane, referred to as the retina. The retina contains over one hundred million photoreceptor cells that function as detectors by chemically altering in response to light. When the rods of the eye are stimulated by light, a light-sensitive pigment known as rhodopsin changes chemically, converting light into electrical impulses that are sent to the brain. Rhodopsin is made up of 2 pigments: opsin and retinal, a form of vitamin A

11-cis-retinal is a derivative of vitamin A. It is responsible for regenerating rhodopsin after the rod cells have been subjected to bright light. Vitamin A is therefore critical in maintaining normal functioning of the retina and aids in our ability to see in the dark via dark adaptation.

Think of your eyes as a digital camera. A high-quality lens is needed to take a high-quality photo and an image cannot be taken in the dark without using the camera’s flash. Once the picture is taken, it is displayed on your camera’s screen. Connections within the camera link the lens to the screen, and make the picture viewable. Rhodopsin is comparable to the flash by making dim-light vision possible. We are able to see an image by way of light passing through the lens, onto the photoreceptors, and down the optic nerve to the brain. Just as high-quality lenses take clearer photos, healthier eyes are capable of seeing better, in both bright light and darkness.

The TakeAway

Though carrots are a good source of vitamin A, eating them will not give you night vision superpowers. Carrots are, however, a rich source of beta-carotene, which can be converted to vitamin A for use of the eyes in low-light settings.

Retinol allows the eye to utilize light, so having adequate vitamin A stores aids the process by which we see. Sufficient intake also prevents night blindness caused by vitamin A deficiency, known as Xerophthalmia. 

For the average well-nourished American, eating carrots or ingesting large doses of vitamin A via supplementation will not have a significant effect on night vision. The best prescription for eye health? A well-balanced diet that is rich in fruits and vegetables, carrots included.

References:

  1. Harvard Health Publishing. (2007, June). Blinded by the night.
  2. Kruszelnicki, K. S. (2005, October 25). Carrots & Night Vision.
  3. Paget, G. (2015, October 12). Mythbuster: Do carrots really help you see in the dark?

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