White spots on nails are not caused by calcium deficiency. It is more likely that these spots, or leukonychia, are calcium deposits caused by hitting your nail at its base or matrix. Because a normal fingernail takes about eight months to grow out completely, the mark might not appear for several months: if you see white spots halfway up your nail, the damage probably happened around four months earlier.
White spots can also be due to dehydration – simply not drinking enough water or using a nail polish remover with too much formaldehyde or toluene. Other causes include allergy to nail products used, a fungal infection or mild zinc deficiency caused by changing hormone levels, colds or viral infections.
If you want strong, healthy nails, be sure that your diet is rich in vitamins A, B, C, D, E and iron, calcium, zinc and sulphur, as well as the essential fatty acids.
Thanks to tescodiets.com who have provided this article.