Welcome back to Just Curious, Strong Women’s weekly series exploring all the random health and fitness questions you’ve always wondered about but never got the answers to.

This week, we’re exploring all the reasons why you might get white spots under your nails – and no, it’s probably not got anything to do with a calcium deficiency.  

From the idea that eating carrots can help you see in the dark to the belief that cracking your knuckles can cause arthritis, many of us grew up being fed old wives’ tales about our health. Most of these, of course, turned out not to be true – carrots may contain vitamin A (which is essential for eye health), but they’re not going to suddenly give you night vision.

But did you know that the commonly held belief that calcium deficiency is to blame for any white spots under your nails is likely another one of those myths? It turns out that these white spots – medically known as punctate leukonychia – can be triggered by a whole host of factors, but a nutrient deficiency isn’t likely to be one of them. 

So, do these white spots have anything to do with calcium? And what other factors could be at play? To find out, we spoke to Dr Magnus Lynch, a consultant dermatologist and surgeon.  

If you’re worried the white spots on your nails could be a sign of a nutrient deficiency, then you can take a sigh of relief – Dr Lynch says that’s likely not the cause.

“The jury is out on this one – some doctors believe that a calcium or zinc deficiency may cause white spots on the nail, but there is limited evidence,” he explains. “Either way, it is not likely to be a common cause.”

It’s worth noting that calcium deficiency can be serious, so if you are worried you’re low on calcium and have been experiencing the common symptoms of calcium deficiency – such as weakness, fatigue, muscle cramps and numbness or tingling in the fingertips or jawline – it’s worth paying a visit to your GP who will be able to investigate.  

Dr Lynch says there are three common causes of white spots under the nail: minor trauma or injuries to the nail, allergic reactions to substances such as nail varnish or fungal infections.

“When there’s trauma or injury to the nail matrix (the area where nail growth begins), it can disrupt the normal nail formation process,” he explains. “Even something as simple as banging your fingernail against a hard surface can cause this.”

In this case, the white spot will appear from the nail bed, as it’s caused by a disruption to the growth of the nail. “This will present as white spots as the nail grows out,” Dr Lynch adds.

If a fungal infection is to blame, it’ll be caused by dermatophytes – fungi that appear on the skin, hair or nails and require keratin for growth.  

“In this case, the discoloration is caused by the fungus growing in the superficial layer of the nail,” Dr Lynch says. “These spots may gradually grow out with the nail as it continues to grow, eventually disappearing as the affected part of the nail is replaced by new growth.”

It’s worth noting that nails grow slowly, so this process can take a while. On average, fingernails take up to six months to grow out completely.  

The good news: no, you rarely need to treat these kinds of white spots because they’re often completely harmless.

“Treatment is only needed if the patient is concerned or experiencing other symptoms,” Dr Lynch adds. In this case, the doctor might take a clipping of your nail to see if there’s a fungal infection at play or look into other conditions that relate to your other symptoms.

If a fungal infection is detected, antifungal medications may be offered. 

Images: Getty