Vitamin D, nicknamed the ‘sunshine vitamin’ is created by the body from direct sunlight on the skin. The vitamin is an important one, regulating the amount of calcium and phosphate in the body – essential nutrients for keeping bones, teeth and muscles healthy. If a person lacks vitamin D they may be at increased risk of developing bone deformities or bone pain caused by a condition called osteomalacia. From late March and early April to the end of September, most people should be able to get all the vitamin D they need from sunlight.
But between October and early March, it can be more difficult to get enough vitamin D from sunlight.
Spotting the symptoms of vitamin D deficiency can help prevent more severe health problems developing, and one sign which has a growing body of research surrounding it is poor sleep.
One study found vitamin D deficiency is linked to short sleep duration. (https://www.ncbi.nlm.nih.gov/pubmed/28686746)
The study found links between insufficient sleep and lack of vitamin D to be especially strong in adults age 50 and older.
More than half of the people included in the study were deficient in vitamin D.
In 2018, scientists at China’s Qingdao University analysed the findings of several studies that looked at vitamin D’s role in sleep.
Their analysis found significant connections between low levels of vitamin D and a lack of sleep.
They also found low levels of vitamin D were connected to poor sleep quality.
A number of other studies have also shown a connection between vitamin D deficiency and risk of sleep apnea.
Vitamin D foods
Small amounts of vitamin D are found in some foods. During the winter months you may want to consider eating more of these:
Oily fish – such as salmon, sardines, herring and mackerel
Fortified foods – such as most fat spreads and some breakfast cereals
Vitamin D supplements
Another source of vitamin D is dietary supplements.
Experts during the autumn and winter months to get vitamin D from your diet.
But since it’s difficult for people to get enough vitamin D from food alone, a daily supplement containing 10 micrograms should be considered.
But the NHS warns: “Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart.
“If you choose to take vitamin D supplements, 10 micrograms a day will be enough for most people.
“Don’t take more than 100 micrograms of vitamin D a day as it could be harmful.”
Who’s at risk of vitamin D deficiency?
Some people may not get enough vitamin D from sunlight because they have very little or no sunshine exposure.
The Department of Health recommends you take a daily supplement if you:
Aren’t often outdoors – for example, if you’re frail or housebound
Are in an institution like a care home
Usually wear clothes that cover up most of your skin when outdoors
People with dark skin, for example people with an African, African-Caribbean or south Asian background, may also not get enough vitamin D from sunlight.
Vitamin D deficiency symptoms may develop if a person’s body isn’t creating enough of the vitamin. The body creates vitamin D from direct sunlight on the skin when outdoors, and during late March to the end of September this is easiest to gain. But between October and early March it can be more difficult to get enough vitamin D from sunlight. Vitamin D is essential for regulating key nutrients in the body, calcium and phosphate.
Calcium and phosphate are needed to keep bones, teeth and muscles healthy, so if a person lacks the vitamin they can be at increased risk of problems with their bones.
Children deficient in vitamin D can be at increased risk of developing rickets, a condition that causes pain and soft and weak bones.
Adults can be at increased risk of developing bone pain caused by osteomalacia.
But complications can be avoided by spotting the symptoms of vitamin D deficiency.
One symptom that may develop, signalling the condition, is dry eyes.
Research published in the International Journal of Rheumatic Diseases, showed vitamin D deficiency is strongly associated with dry eyes.
There are four signs of dry eyes you should be wary of, according to the NHS.
Feelings of dryness, grittiness or soreness that get worse throughout the day
Burning and red eyes
Eyelids that stick together when you wake up
Temporarily blurred vision, which usually improves when you blink
The health body adds: “Some people may also have episodes of watering eyes, which can occur if the eye tries to relieve the irritation by producing more tears.”
According to the researchers of the study, vitamin D plays a role in dry eyes due to its anti-inflammatory properties.
They added vitamin D may help prevent dry eyes by inducing cathelicidin, an anti-microbial protein that can help heal eye wounds.
The study involved 50 women who were deficient in vitamin D and 48 women sufficient in vitamin D.
Only pre-menopausal women took part in the study, as postmenopausal hormonal changes have been found to be associated with dry eye.
Summarising the findings of the study, the researchers said: “To our knowledge, our study is the first to demonstrate the association between dry eye and clinical parameters of hypovitaminosis D such a fatigue, functional impairment and pain.”
They added: “We are of the opinion that vitamin D plays a protective role in the development of dry eye, probably by enhancing tear film parameters and reducing ocular surface inflammation…vitamin D supplementation may be useful for dry eye symptoms, including ocular discomfort, soreness, redness, ocular fatigue, sensitivity to light and blurred vision.”
People at risk of vitamin D deficiency
Certain groups of people risk not getting enough vitamin D from sunlight because they have very little or no sunshine exposure.
But it can be difficult to get enough vitamin D from food alone, so people should consider taking a daily supplement containing 10 micrograms.
The NHS advises: “You can buy vitamin D supplements or vitamin drops containing vitamin D (for under 5s) at most pharmacies and supermarkets.”