SINGAPORE – Why are many Singapore residents deficient in vitamin D? Will vitamin E boost your
skincare routine
? Why are newborn babies in Singapore given an injection of vitamin K? In this second of a two-part series, we find out about these essential nutrients.
What to eat: Eggs; fatty fish such as salmon, mackerel, sardines and tuna; foods that have been fortified with vitamin D.
Vitamin D supports the immune system, muscle function and bone health, since it regulates the amount of calcium in the body.
It is commonly known as the “sunshine vitamin” because one of its two forms, vitamin D3, is produced by the skin when exposed to sunlight. The other form, vitamin D2, is derived from plant sources and fortified foods, and is less effective at raising blood serum levels of vitamin D.
Despite the sunny weather in Singapore, various studies on the local population over the years have shown that at least 30 per cent of those studied were deficient in vitamin D.
A study by KK Women’s and Children’s Hospital (KKH), published in 2024
in the journal PLoS One, found that up to 90 per cent of the pregnant women studied had insufficient levels of vitamin D.
The Health Promotion Board’s (HPB)
recommended dietary allowance
of vitamin D is 2.5mcg for adults aged 18 and above. Pregnant or breastfeeding women require 10mcg a day.
Professor Jerry Chan, senior consultant at KKH’s department of reproductive medicine, says that high awareness of sun protection could be the reason many in Singapore have insufficient vitamin D.
“Many people frequently use sun shields and covered clothes, as well as lead indoor and sedentary lifestyles,” he says. “Our expectant mothers tend to stay indoors and use sun protection outdoors.”
recommend 15 to 30 minutes of sun exposure, but people with darker or tanned skin might require more
, as the melanin in the skin reduces the vitamin-producing effect of ultraviolet radiation.
Dr Glenn Low, a physician at private practice DTAP Clinic, says another reason for vitamin D deficiency could be an unbalanced diet.
Eggs and fatty fish are the main sources of this vitamin. “Dairy and plant-based products normally contain very little vitamin D, and typically need to be fortified with it,” he says.
Prof Chan, who is also director of the KKH Maternal and Child Health Research Institute, says pregnant women need an adequate amount of vitamin D to reduce the risk of complications in pregnancies such as pre-term birth and low birth weight in infants.
All pregnant patients at KKH, as well as those who intend to conceive, are prescribed multivitamins that include vitamin D, as well as vitamin B. Deficiencies in both vitamins are prevalent in the Singapore population.
Dr Rachel Chin, a general practitioner at DA MedSuites, says vitamin D deficiency results in bones becoming weak or soft. In children, this condition, called rickets, will affect bone development and increase the risk of fractures.
Adults are at risk of developing osteoporosis or brittle bones, as well as impaired immune function and muscle weakness.
Dr Chin says that bone-softening conditions like rickets, or osteomalacia in adults, can be reversed with vitamin D and calcium supplementation.
“However, it takes time, often months, to restore bone mineral density. The earlier the supplementation starts, the better the long-term prognosis,” she says.
Dr Chin adds that vitamin D is fat-soluble and stored in the body. Taking excessive supplements of vitamin D can lead to a build-up of calcium in the blood, or hypercalcaemia.
Hypercalcaemia can cause nausea, vomiting, excessive thirst and urination. It can also lead to kidney stones and kidney damage.
“People often assume that because they live in a sunny place but are deficient, they need extremely high doses, which is incorrect and risky,” says Dr Chin. “Before starting any high-dose vitamin D regimen, it is crucial to establish a baseline blood level.”
Creams containing vitamin E can help protect the skin.
PHOTO: ADOBE STOCK
What to eat: Fortified cereals, green leafy vegetables, nuts, seeds, vegetable oils.
Ms Sharon Teoh, dietitian at Singapore General Hospital, calls vitamin E a potent antioxidant. It protects cells from the damage caused by free radicals. It is important for nerve and muscle function, and also immune health.
Moisturisers and other skincare products often advertise vitamin E as an ingredient. Dermatologists say that applying creams with vitamin E could help support the skin barrier, or protective outer layer of skin, at the site of application.
However, topical application does not make vitamin E available to the rest of the body.
DTAP Clinic’s Dr Low says this is because the skin itself functions as a barrier to prevent substances from entering the bloodstream.
Ms Teoh says most people get enough vitamin E for their needs from natural food sources, by eating a varied and balanced diet.
“Vitamin E deficiency is very rare,” she adds.
HPB does not have a recommended dietary allowance for vitamin E, but United States authorities recommend 15mg daily for most adults, while breastfeeding women are recommended 19mg daily.
In Singapore, the Health Sciences Authority specifies an upper limit of 536mg in vitamin E supplements.
Ms Teoh says that excessive vitamin E increases the risk of bleeding, especially in people taking blood thinners.
She adds that vitamin E is fat-soluble and deficiencies can manifest in people with medical conditions that affect fat absorption. People at risk include those with chronic pancreatitis, pancreatic insufficiency and Crohn’s disease, an inflammatory bowel disease where the digestive tract is inflamed.
Premature and low-birth-weight infants are among the highest-risk groups, adds Ms Teoh. The placenta does not transfer sufficient vitamin E to the foetus before birth, and so infants have low stores. They may develop haemolytic anaemia or have fragile red blood cells.
These conditions are generally reversible with vitamin E therapy.
When vitamin E deficiency does occur, it can lead to a weakened immune system and slower wound healing. People may experience muscle weakness, poor coordination or difficulty walking. Vision problems can also develop.
“Without vitamin E’s antioxidant protection, retinal cells break down and blood vessels become damaged, leading to progressive visual loss,” says Ms Teoh. “These symptoms may improve if treated early. Severe damage can be permanent.”
What to eat: Asparagus, celery and leafy green vegetables such as spinach, kale and broccoli.
Newborns at KKH get an intramuscular injection of vitamin K in their first few hours of life. This is to prevent neonatal haemorrhagic disease, a bleeding disorder caused by vitamin K deficiency.
Dr Nirmal Kavalloor Visruthan, head of KKH’s Neonatal Intensive Care Unit at its department of neonatology, says newborns naturally have low levels of vitamin K.
“Vitamin K does not pass effectively from mother to baby via the placenta. Therefore, newborns have vitamin K deficiency at birth even if the mother takes vitamin K supplements during pregnancy,” he says.
“Their gut takes several weeks to months to develop the bacteria needed to produce it, and breast milk contains limited amounts,” he adds. “Vitamin K is essential for blood clotting, so supplementation at birth helps prevent serious bleeding complications.”
Vitamin K is required for blood clotting, bone health and cardiovascular function, says Ms Teoh from SGH.
HPB does not have a recommended dietary allowance for vitamin K, but the US recommends 90mcg for women and 120 mcg for men, she adds. HSA has an upper limit of 120mcg for vitamin K in oral multivitamins for adults.
Ms Teoh says toxicity from vitamin K is very rare, but the nutrient can interfere with the effects of anticoagulant medications.
People on the blood thinner warfarin are often referred to a dietitian to ensure that their vitamin K intake remains consistent, she adds.
Patients may start limiting their diets after being prescribed the blood thinner. Some try to avoid vegetables such as spinach, for example.
“We tell them that they don’t need to change their diets. They have to keep their diet consistent so that their dietary vitamin K is consistent,” she says.
