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Folk wisdom has a way of lingering, as people usually share them with good intentions. And sometimes they contain a surprising kernel of truth. So, what’s the deal with the age-old claims that carrots help your vision and beetroot is good for your blood?
Let’s start with carrots. These humble root vegetables are rich in beta-carotene, a type of antioxidant that our bodies convert into vitamin A. This vitamin plays a crucial role in maintaining healthy vision – particularly in low-light conditions. So, yes, in one sense, carrots do help your eyesight. But it’s not the whole story.
Vitamin A plays several roles in our vision, including an essential role in producing rhodopsin, a pigment in the retina that allows us to see in dim light. Without enough vitamin A, we can develop night blindness – a condition where vision becomes impaired in the dark. Indeed, night blindness can be an early symptom of a vitamin A deficiency. In that context, carrots and other vitamin A-rich foods (such as leafy greens and orange fruit) are essential for preventing deficiency-related vision issues.
But eating carrots beyond your vitamin A needs, sadly, won’t give you night-vision superpowers or sharpen your eyesight like a telescope. That idea was popularised during World War II, when British propaganda exaggerated the benefits of carrots to explain away the success of Royal Air Force pilots – when, in fact, the RAF was using new-fangled onboard radar systems.
When it comes to preventing eye diseases, observational studies suggest diets rich in antioxidant-packed vegetables (including carrots) can reduce the risk of developing age-related macular degeneration (AMD) – the leading cause of vision loss in older New Zealanders. This protective effect is believed to stem from antioxidants reducing oxidative stress in the eye, particularly in the macula, the central part of the retina responsible for detailed vision.
In fact, clinical trials such as the US-based AREDS2 study found that a combination of antioxidant nutrients in supplement form – including lutein and zeaxanthin (carotenoids found in dark green vegetables) – may slow the progression of AMD. But interestingly, beta-carotene (the form of vitamin A found in carrots) was eventually dropped from the recommended supplement due to a link with increased lung cancer risk in smokers.
So while carrots do play a role in supporting eye health, they’re part of a broader picture: a diet high in colourful fruits and vegetables is protective, but no single vegetable is a miracle cure for poor vision.
The folk tale that beetroot is good for your blood has been shown to have robust science behind it.
Beetroot is naturally high in dietary nitrates – compounds that the body converts into nitric oxide. Nitric oxide helps relax and dilate blood vessels, improving circulation and lowering blood pressure. Clinical trials have repeatedly shown that beetroot juice can lead to modest but significant reductions in blood pressure, particularly among people with hypertension (high blood pressure).
That’s not all. Nitric oxide may also enhance physical performance by improving blood flow to muscles and reducing the amount of oxygen your body needs during exercise, thus enabling the body to work more efficiently. These findings have made beetroot juice particularly popular among endurance athletes.
Significantly, though, the health effects of nitrates depend heavily on their source. Nitrates from processed meats, such as bacon or ham, are linked with a higher cancer risk due to the potential formation of carcinogenic nitrosamines. Nitrates from vegetables such as beetroot are combined with antioxidants from the vegetables which steer the body’s nitrate metabolism towards beneficial nitric oxide production rather than harmful byproducts like nitrosamines.
A 2024 Danish study affirmed this, showing that among the observed 52,247 Danish adults, plant-based nitrates were associated with lower risks of cardiovascular disease and cancer. In contrast, nitrates from tap water or animal sources were linked with higher mortality risks.
So, are these tales true? Partly. Carrots won’t give you super sight, but they can help prevent vitamin A deficiency and support long-term eye health. And beetroot really does benefit your blood pressure and vascular function when eaten as part of a plant-rich diet.
Perhaps the wisdom passed down the ages deserves more credit: they knew the value of vegetables long before scientists caught up with their clinical trials.
As well as Jennifer Bowden’s columns in the NZ Listener,listener.co.nz subscribers can access her fortnightly myth-buster column which explores food and nutrition myths.
