“We live in a sunny country, surely we cannot be low in vitamin D?”
This is something I often hear from parents.
Understandably so as Malaysia enjoys sunshine all year round as we are near the equator.
Most would assume that vitamin D deficiency is a problem for colder climates, not ours.
Yet, research shows otherwise.
Vitamin D deficiency is surprisingly common in Malaysia.
It affects people of all ages, from babies to adults, even those who appear healthy.
A hidden problem in plain sight
Five-year-old Lina had always been full of energy, especially at school, but lately, her mother had started noticing something odd.
Lina had started sleeping more than usual after coming home.
At first, it seemed normal.
Maybe she was just worn out from all that running and playing.
But soon, her mother spotted something that didn’t sit right: Lina’s legs looked slightly bowed.
That’s when concern kicked in.
They brought her to the paediatrician.
A blood test revealed that Lina’s 25-hydroxyvitamin D [25(OH)D] level was only 25 nmol/L, far below the recommended level.
With proper vitamin D supplementation, dietary improvements, and regular, safe sun exposure, Lina’s vitamin D levels slowly recovered.
Her energy returned, and over time, her legs began to straighten.
What began as something easily brushed off, like extra-long naps and tired legs, turned out to be nutritional rickets caused by vitamin D deficiency.
Lina’s story is not uncommon.
Many children may show no clear signs of vitamin D deficiency until something prompts a check.
This is why awareness matters.
Even in sunny Malaysia, this silent deficiency can quietly affect a child’s growth and well-being.
Many Malaysians are lacking
So, how common is vitamin D deficiency in Malaysia?
A systematic review published in 2022 estimated that over half of Malaysian adults have serum 25(OH)D levels below 50 nmol/L, which is the level widely accepted as the threshold for sufficiency.
Urban residents were found to have lower levels compared to rural communities.
This is likely due to more time spent indoors, as well as sun-avoidant behaviour.
Studies also show that Malay and Indian adults have higher deficiency rates than Chinese, partly due to darker skin tone and culturally-influenced clothing that limits sun exposure.
In pregnant women, deficiency rates were even more alarming, ranging from 60% to 90%.
Low vitamin D in pregnancy affects the developing baby, increasing the risk of neonatal hypocalcaemia (low calcium levels), rickets in infancy, and poor bone development.
Meanwhile, a study of 1,361 adolescents aged 12 to 13 years, conducted in Perak, Selangor and Kuala Lumpur, found that 78.9% were deficient in vitamin D (with levels less than 50 nmol/L) and 13.7% were insufficient (with levels of 50-75 nmol/L).
Girls and Indian adolescents were the most affected.
Another study on 15-year-olds reported that one-third had severe deficiency (vitamin D levels less than 30 nmol/L), influenced by gender, ethnicity and limited sun exposure due to clothing.
According to the first phase of the South-East Asian Nutrition Surveys (Seanuts) in Malaysia, around 47% of children aged four to 12 years were vitamin D deficient.
Seanuts II, which was conducted a decade later, showed some improvement, with the number dropping to 25%.
Despite the decline, it remains a significant concern.
Many of these children also had poor calcium intake, adding to the risk of bone-related problems.
Why does it matter?
Vitamin D helps the body absorb calcium and phosphate, which are essential for strong bones.
When levels are too low, this can lead to the following:
- Rickets in children – soft, bowed legs, widened wrists, delayed growth and bone pain
- Osteomalacia and osteoporosis in adults – bone weakness, pain and higher fracture risk
- Hypocalcaemia – low calcium in the blood that can cause cramps, muscle spasms (tetany), seizures and secondary hyperparathyroidism
- Weakened immune response – more frequent respiratory infections, worsening of eczema or asthma, and possible autoimmune flares.
Vitamin D also supports other areas of health, such as:
It plays a central role in bone mineralisation.
In children, a deficiency can lead to long-term deformities and stunted growth.
Vitamin D helps regulate immune responses.
Low levels are linked to higher infection rates, particularly of the respiratory tract.
Studies have associated vitamin D deficiency with insulin resistance, type 2 diabetes and cardiovascular (heart) risks.
Some individuals with low vitamin D report feeling more tired.
Observational studies have linked low levels to depression, especially in urban women.
Some research has noted associations between low vitamin D levels and higher risks of colorectal, breast and prostate cancers, although more robust studies are needed to confirm causality.
Those at risk
There are certain groups of people who are more at risk of vitamin D deficiency:
- Those with limited sun exposure – office workers, students and those living in high-rise buildings
- Those with darker skin tones – more melanin in the skin reduces vitamin D production
- Pregnant and breastfeeding women – their requirements are higher and deficiencies can affect the baby
- Exclusively-breastfed infants – while breast milk is ideal for babies, it contains little vitamin D; the American Academy of Pediatrics recommends 400 IU per day for breastfed babies
- Older adults and menopausal women
- Obese individuals – vitamin D is fat-soluble and can get stored in fat tissue, making it less available for use in the body
- Those who regularly wear modest clothing – covering the arms and legs limits skin exposure to sunlight.
Several lifestyle and environmental factors are at play when it comes to why Malaysians still deficient in vitamin D despite having potential sun exposure all year round. These include:
Many of us spend most of our time inside, e.g. in offices, classrooms, malls or cars.
This means little exposure to the midday sun, which is needed for the skin to produce vitamin D.
Concerns about tanned skin or sun damage lead many to cover up, use sunblock or avoid the sun altogether.
UVB (ultraviolet B) rays are necessary for vitamin D synthesis.
In polluted urban areas, UVB rays are partially blocked by haze and smog.
As vitamin D is stored in fat, people with higher body fat percentages may have reduced circulating vitamin D.
How to prevent it
The following are some of the steps we can take to prevent vitamin D deficiency:
Aim for 10 to 20 minutes of direct sun exposure, two to three times a week.
The best time is between late morning and early afternoon.
These include fatty fish such as salmon, sardines and mackerel; egg yolks; and vitamin D fortified foods like milk, plant-based milk and cereals
The recommended daily intakes for vitamin D are 400 IU per day for infants under one year of age, and 600 IU per day for children aged one to 18 years.
Children who have minimal sun exposure, poor diets or medical conditions may need higher doses.
Always consult your doctor before starting supplementation.
Also ensure adequate calcium intake, as both nutrients work together to maintain healthy bones.
Routine vitamin D testing is not necessary for every child.
However, do speak to your paediatrician or paediatric endocrinologist if your child:
- Has bowed legs, bone pain or slow growth
- Has low calcium or phosphate levels
- Eats very little and gets minimal sun
- Has had a low-impact fracture
- Has conditions like obesity, coeliac disease, liver or kidney problems
- Is taking long-term medications such as anticonvulsants
- Shows other signs of poor bone health.
A serum 25(OH)D test can help determine if supplementation is needed.
Your doctor will be able to tailor a treatment plan and monitor your child’s progress.
A solvable problem
Vitamin D deficiency in Malaysia may be silent, but it is certainly real.
In a country with abundant sunshine, this may come as a surprise.
However, our modern habits of staying indoors, covering up and poor dietary intake may have created a hidden public health issue.
Fortunately, it is one we can address.
With awareness, good habits and medical support where needed, we can ensure our children grow up strong, healthy and ready to shine.
Dr Jeanne Wong Sze Lyn is a consultant paediatrician and paediatric endocrinologist. For more information, email starhealth@thestar.com.my. The information provided is for educational purposes only and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
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