Do you lack vitamin D? Here's what you should know

Joanne Ang was exercising at home in April last year when she slipped and fell on her yoga mat. She was taken to Ng Teng Fong General Hospital, where she learnt she had suffered a hip fracture.

“I was shocked that I had an injury as serious as a hip fracture and it was not a freak accident,” said the 32-year-old, who owns a skincare business.

She was diagnosed with osteopenia – a condition characterised by low bone mass and weak bones. The doctor told her she was deficient in vitamin D, which increases the risk of fractures.

Ang subsequently underwent an operation to insert three screws in her left hip. She was also prescribed with vitamin D and calcium supplements, which she is still taking.

(Here are "The Most Common Health Supplements At A Quick Glance")

Joanne Ang discovered she was deficient in vitamin D when she suffered a hip fracture after a fall last year. She was found to have osteopenia, a condition characterised by low bone mass and weak bones.

Like her, many people in Singapore lack vitamin D even though there is abundant sunshine here, doctors tell The Straits Times.

A normal level of vitamin D is 30 to 100 nanograms (ng) per millilitre (ml). An insufficient level is classified as below 30ng per ml, while 10ng per ml and below is considered deficient.

Vitamin D deficiency can lead to osteoporosis, a lower immunity to infections and a higher risk of autoimmune disease, among other issues.

Earlier this month, it was reported that Temasek Foundation would provide a two-month supply of vitamin D supplements free of charge to low-income households consisting of vulnerable groups, including seniors and expectant mothers.

Commonly called the “sunshine vitamin”, vitamin D is mainly produced in the skin when it is exposed to the ultraviolet B (UVB) rays of the sun.

(Read also "Take These Oral Supplements To Strengthen Your Skin Against UV Rays")

The vitamin is involved in calcium absorption, immune function, and protecting bone, muscle and heart health.

Dr Derek Koh, head of medical health screening at Thomson Wellth Clinic, said about 80 per cent of his clinic’s patients between the ages of 30 and 70 have low levels of, or are deficient in, vitamin D.

“Most Singaporeans are not exposed much to the sun as they are largely covered by clothes and shaded by umbrellas in the afternoon,” he said.

Dr Nitish Mishra, an endocrinologist at Singapore Medical Group’s Diabetes, Thyroid and Endocrine Clinic, also said two- thirds of his patients are vitamin D deficient.

Dr Derek Koh, head of medical health screening at Thomson Wellth Clinic, said about 80 per cent of his clinic’s patients between the ages of 30 and 70 have low levels of, or are deficient in, vitamin D.

“Most Singaporeans are not exposed much to the sun as they are largely covered by clothes and shaded by umbrellas in the afternoon,” he said.

Dr Nitish Mishra, an endocrinologist at Singapore Medical Group’s Diabetes, Thyroid and Endocrine Clinic, also said two- thirds of his patients are vitamin D deficient.

A study published in 2019 in the International Journal of Environmental Research and Public Health found the prevalence of vitamin D deficiency among indoor workers here was 32.9 per cent.

Symptoms of vitamin D deficiency include fatigue and lethargy, bone pain, muscle pain and falling sick often.

Dr Charu Malik Narayanan, a family practitioner at International Medical Clinic, said people who spend most of their time working indoors and away from direct sunlight may not expose their skin to ultraviolet rays for production of vitamin D. Sitting by a window may not help as UVB radiation does not penetrate glass, she added.

Ang, a former flight attendant at Singapore Airlines, said: “I hardly saw the sun or went out into it. That could have been a reason why I was vitamin D deficient.”

Healthcare worker Sajunnisa Sameema, 39, suddenly experienced fatigue and knee pain in 2016. She took a blood test at Choa Chu Kang Polyclinic and found out she was deficient in vitamin D.

She was prescribed with an eight-week dosage of ergo-calciferol, a supplement to treat the deficiency.

She said she usually stayed out of the sun during the day due to the nature of her job. “I work in an air-conditioned environment for long hours and tend to avoid the sun because of the heat.”

Symptoms of vitamin D deficiency include fatigue and lethargy, bone pain, muscle pain and falling sick often.

Unlike Sameema, doctors said, many people with vitamin D deficiency have subtle or no symptoms, making it an under-detected problem.

Said Thomson Wellth Clinic’s Dr Koh: “It is usually discovered only when a patient undergoes a health screening or specifically screens for it, or if the patient has osteoporosis and a follow-up vitamin D check is ordered by the doctor.”

Doctors said sun protection practices such as using sunblock, wearing a hat or long sleeves, or using an umbrella can all reduce the production of vitamin D.

Dr Koh said: “While we know the harmful effects of UV light on the skin, we can benefit from the positive effects of sunlight without putting ourselves at risk too. Balance is key.”

Many people with vitamin D deficiency have subtle or no symptoms, making it an under-detected problem.

People with naturally dark skin are also at greater risk. Dr Narayanan said: “The darker a person is, the more melanin (skin pigment) the person has, which blocks ultraviolet rays from penetrating the skin – thus not allowing vitamin D to be produced.”

The elderly, as well as pregnant women, are also at higher risk of vitamin D deficiency.

Apart from being indoors most of the time, seniors are unable to produce much vitamin D with sun exposure due to the thinning of the skin with age, said Dr Koh.

Pregnant women also tend to have low levels of vitamin D as the foetus draws its nutrients from the mother.

Dr Koh added that haemodilution, which occurs during pregnancy, may also result in low levels of vitamin D. Haemodilution refers to an increase in blood volume, which can dilute vitamin D levels in the blood and, in turn, the rest of the body.

A sufficient amount of vitamin D in pregnant women reduces the risk of complications in pregnancies, such as pre-term birth and low birth weight in infants.

The lack of vitamin D also affects people who have liver or kidney disease, as these organs are unable to adequately convert active vitamin D in the body.

Said Dr Koh: “Easily half of my patients are not familiar with the importance of vitamin D. Those who know (about it) know only of its role in the prevention of osteoporosis.”

Dr Mishra said the Covid-19 pandemic may have indirectly worsened people’s levels of vitamin D “as they spend more time indoors and may not be exposed to adequate sunlight”.

Overall, doctors stressed that the importance of vitamin D cannot be ignored. Their advice is to eat food rich in vitamin D, such as eggs and oily fish, and get adequate exposure to sunlight.

Spend more time in the sunlight

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Doctors advise people to go out in the sun to increase the absorption of vitamin D into the skin. However, this should be balanced against the sun’s effects on skin ageing and cancer.

Dr Nitish Mishra, an endocrinologist at Singapore Medical Group’s Diabetes, Thyroid and Endocrine Clinic, recommends sun exposure on arms and legs for an hour five times a week.

He suggests dividing sun exposure into three 20-minute sessions with the application of sunblock. “Sunblock creams do not completely block ultraviolet B (UVB) rays and even 5 to 10 per cent exposure of UVB rays for an hour each day may be enough for vitamin D synthesis.”

(Read also "HWBA 2021: The Best Sunscreens To Protect Your Skin All Day, Every Day")

Eat food rich in vitamin D

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The daily recommended dietary allowance of vitamin D for those aged 18 and above is 2 1/2 micrograms. Vitamin D can be found in eggs, liver and oily fish such as salmon, sardine and mackerel. Other sources include fortified food products such as milk, soya milk, yogurt, orange juice, breakfast cereals and margarine.

Photo: Still Life Fish, William Merritt Chase, oil on canvas, 101.9 x 114.5 cm/The Metropolitan Museum of Art

Consider taking supplements

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Dr Derek Koh, head of medical health screening at Thomson Wellth Clinic, says people may not have time to go out into the sun. “Not many women appreciate the bronzed look and many of my male patients are professionals who wear long pants and sleeved shirts daily.”

He advises patients to take “a more practical approach” by taking a vitamin D supplement daily. People can consult a doctor before starting such a supplement or any high-dosage supplement.

This article was first published in Female.