They’re good for scratching and scraping, and they look lovely when painted—but did you know that your nails can also provide insight into your health?

The nail plate is a surprisingly complex structure. It’s formed largely of sulphur-rich keratin (the same protein that makes up your hair) and is strengthened by a host of minerals. It also contains fats, which help keep it waterproof.

Studies suggest that the nutrient levels in your nails correlate with nutrient levels in the rest of your body [1]. This association—coupled with the fact that it takes half a year to grow an entirely new nail plate—means your current nails can give clues about how your health has been faring for the last 6 months.

On the extreme end of the scale, high arsenic in nails can be used to diagnose arsenic poisoning. On a more day-to-day basis, certain nail characteristics can suggest we pay attention to our intake of certain nutrients. This is by no means prescriptive, as the quality and growth of our nails can be affected by almost any nutrient deficiency. However, it can be a good place to start.

So, take a break from acrylics, remove your shellac or wipe off that polish and peer at your natural nails. You may find that they’re telling you something.

Brittle nails

Are your nails dry, weak or thin? Do you find they break easily? If so, you’re not alone. It’s estimated that 1 in 5 adults suffers from brittle nails.

First things first, consider your protein intake. It’s the proteins in the nail matrix that create its hardness so, for optimal strength, you want to make sure you’re getting enough of this macronutrient. Aim for at least 0.75g per kilogram of body weight per day, or simply make sure you eat a palm-sized portion of protein with each meal.

Another thing to consider is how much water you’re drinking. Nails are typically 18% water. When they drop below 16%, they can become dry and prone to breakage [2].

As a final step, amp up your zinc intake. A deficiency of this mineral has been found to contribute to brittle nails [3]. Good sources of zinc include oysters, beef, sesame seeds, pumpkin seeds and lentils, or you can also supplement with zinc picolinate. Take 15–30mg daily for 3 months.

Flaky nails

This is subtly different to brittle nails. Rather than breaking outright, they tend to peel or split easily.

Nails contain a plethora of minerals, including magnesium, copper, iron, calcium, and the aforementioned zinc. All of these are important, but studies have found a particular correlation between low magnesium and flaky nails [4].

Even more interesting is that the fact that women tend to have higher levels of magnesium in their nails than men [5]. This suggests that they need more of this mineral to maintain the same nail integrity.

Happily, magnesium is found is range of everyday foods, including spinach, Swiss chard and a range of pulses. A good starting point is to eat a magnesium-rich side with every meal.

Soft nails

Do your nails bend easily? Perhaps you think twice about using them to scrape off a label, or you may regularly opt for shellac in an attempt to harden them.

Along with your protein intake (see above), it’s important to make sure you’re getting enough vitamin D and vitamin A. Soft nails—technically known as hapalonychia—have been associated with a deficiency of one or both these fat-soluble vitamins [6].

The best way to boost your vitamin D levels is through sensible sun exposure. You can also make sure you eat three servings of vitamin D-rich oily fish every week.

For vitamin A, load up on green and orange vegetables: carrots, butternut squash, spinach, kale and sweet potatoes. As vitamin A is fat-soluble, you’ll absorb more of it if you eat these with a dose of healthy fat. A drizzle of extra virgin olive oil can work perfectly.

White spots

It’s a popular belief that white spots on your nails mean you need more calcium or zinc. Interestingly, though, the research on this is inconclusive [7].

The white spots may be a sign of trauma. This could be down hitting your nail unknowingly, biting them or even handling them a bit too roughly during manicures. The best thing to do is leave your nails polish-free for a month or two and moisturise them regularly. It’s the perfect excuse to treat yourself to a luxury hand-cream! If you’d prefer to keep it simple, coconut oil works well too.

To cover all bases, you can also supplement with a good multivitamin and multi-mineral. For most people, the white spots will grow out in time.

Spoon-shaped nails

Nails that curve gently up at the sides have been associated with iron-deficiency anaemia [8]. If your nail bed (the area under your nail) also looks unusually pale, this is a further sign that you should address your iron intake.

Most people know that one of the best sources of iron is red meat. Vegetarians and vegans should make sure they’re regularly eating lentils, spinach and sesame seeds.

You may also need to supplement with iron, but it’s important you get your levels checked first because it’s possible to take too much. A registered nutritional therapist (or your doctor) can organise a blood test for you.

A quick word on biotin

We don’t yet know the mechanism behind this, but studies show that a variety of nail issues benefit from extra biotin [9]. You can find this vitamin in almonds, sweet potato and eggs, and it tends to be key ingredient in many supplements for skin, hair and nails.

It’s worth nothing that biotin is also synthesised by your gut bacteria. To optimise your levels, eat microbiome-friendly diet based on copious vegetables, fruits and fermented foods. Your nails—and your health as a whole—will thank you for it.

For personalised support, please feel free to get in touch.