Do you have sufficient levels of vitamin D?

Vitamin D sufficiency – and daily dosing to achieve adequacy – is proven by research to boost your immunity. This powerful nutrient helps stimulate production of secretory IgA, an antibody that acts as our immune system’s first line of defence.

At IMI, our clinical observations concur with the plethora of studies on Vitamin D-imbalance. Low vitamin D3 levels are found in those who struggle with low immunity. In initial blood tests, most of our clients with poor immunity have sub-optimal levels of Vitamin D3.

And though famed for helping your immunity, it’s also key to unlocking bone health. Without vitamin D, our body cannot absorb calcium effectively, which is essential for increasing bone mineral density, strengthening bones, teeth and supporting muscle health.

Vitamin D’s importance is wide ranging, and linked to mental health, sleep, your gut, detox and even your hair. It’s key for many biological functions. Studies have linked low vitamin D levels and places with higher latitudes (which have fewer sunshine hours) with increased risk of chronic diseases.

In Hong Kong, we’re lucky to live at a relatively low latitude - 22 degrees. Despite this advantage, studies still show that our population still has insufficient levels. 

Is sunshine the best way to produce vitamin D?

Under sunlight, our skin performs a magic trick – converting UVB rays to previtamin D3, which is then transformed by the body into vitamin D3. Sun exposure (without sunscreen) for 5 to 30 minutes each day between the hours of 11am and 3pm (which is when UVB is high enough for us to synthesise vitamin D3) can help you create enough vitamin D.

Blood levels above 30ng/mL of vitamin D are considered optimal.

Research shows 72% of Hong Kong residents aged 18-26 years have levels of Vitamin D equal to or below 20ng/mL. Young adults had an average level of 13ng/mL  – a sub-optimal level that adversely affects immune function.
In fact, Vitamin D insufficiency is a worldwide epidemic, according to the 334 scientists that met for the 13th workshop on vitamin D. They gathered from 23 countries and concluded that around two thirds of the world’s population are not getting enough vitamin D.

“At least 90% of my patients have low vitamin D levels. Those who have had sufficient levels were a gardener, a paddle boarder and my clients in Phuket, where it’s more common to spend time in the sun,” says naturopathic doctor, Benita Perch. 

However, both our naturopaths and the scientists agree - you shouldn’t expose your skin to sunshine for prolonged periods as a means to raise your levels of vitamin D. 

Though vitamin D synthesis is a benefit of sun exposure, UV rays carry many health risks, harming the cells in your body while increasing oxidative stress and your risk of skin cancer.

“Find a balance,” says Benita. “Spend around 20 minutes in the sun without sun block - even better if you can have your torso exposed, as this provides a large surface area for your skin to synthesise vitamin D. Take care to apply sun block after the 20 minutes is up.”

Why don’t we get enough vitamin D?

In Hong Kong, few of us are lucky enough to enjoy the sunshine when the UVB is high enough for us to transform to vitamin D3 (between the hours of 11am and 3pm). Though you might be able to soak up some rays while sitting at a desk in the sunshine, glass blocks the UVB rays which are needed to create vitamin D.

Protecting your skin with sunscreen when you do go out, and nutrient-poor foods can leave you with insufficient Vitamin D3 all year round.

If you have a darker skin tone, the higher levels of melanin in your skin function as a sunscreen, making it harder for you to synthesise vitamin D from UV rays. Studies show that African Americans, Asian and Hispanic people are more likely to have low vitamin D levels. 

Aging skin can also struggle to produce enough vitamin D from the sunshine. Research demonstrates that between the ages of 20 to 80, the levels of vitamin D in the skin reduce by around 50%.

When you’re overweight, fat absorbs vitamin D, meaning you require a higher intake to achieve optimal levels. People with digestive and malabsorption conditions also require higher intake.

In the winter, the summer high of 8 hours of sunshine a day drops to a wintry four. If you happen to be a sun lover, it is possible to achieve sufficient levels of Vitamin D3 to see you through the winter, but you’ll need a blood level of over 60 ng/mL at the end of the sunny months, and very few achieve this.

In the winter months, you need approximately 45 minutes of exposure to the sun on the arms, legs, face, and hands every second day to achieve optimal levels of Vitamin D3 – which exceeds the recommendations of scientists, and regardless, is a challenge which is infrequently met, leaving your immune system susceptible.

In Hong Kong, these requirements are even higher – as air pollution reduces the intensity of UVB on the earth’s surface – making it harder for you to synthesise vitamin D3.

Dietary sources of vitamin D are primarily found in animal products, leaving vegetarians and vegans vulnerable to insufficiency. Mushrooms contain vitamin D2 (ergocalciferol), whereas vitamin D3 (cholecalciferol) comes from animals. Vitamin D3 is the same kind we’re able to synthesise when sunlight hits our skin and provides the best absorption. 

Symptoms of low vitamin D

But, how do you know if you have the appropriate levels of Vitamin D? The chances are that you don’t. The symptoms of vitamin D insufficiency aren’t loud.

Low vitamin D can affect your energy and emotional health, causing fatigue, mood swings and low mood. It can also contribute to poor sleep, causing wakefulness throughout the night, which in turn can also affect your mental health. 

An increased sensitivity to pain, bone and joint pain, pain and weakness in your muscles, and pins and needles are signs of low levels. 

Insufficient levels can impair your gut health. Vitamin D plays an important role in protecting your gut barrier. It also helps eliminate toxins from the body, and functions as an antioxidant and low levels inhibit your ability to detox. 

These symptoms are often subtle and may increase over time, leading them to be dismissed, or mistaken for other problems. Testing your levels of vitamin D confirms whether you have low levels, so you can take action and restore your health. 

One of the more obvious symptoms is hair loss - vitamin D helps promote follicle growth, and low levels can cause hair to thin.

How to increase your vitamin D

Some foods are good sources of Vitamin D3. Fatty fish like salmon, tuna and mackerel, and  pharmaceutical-grade cod liver oil are excellent sources of Vitamin D3. Small amounts of vitamin D3 are also present in beef liver, cheese, and egg yolks.

Dietary sources of Vitamin D

* IUs = International Units. Daily intake of approximately 1,000IU are needed for sufficient blood levels, but even this amount will not raise the low blood levels commonly found.

Our naturopaths recommend a daily intake of 1000 IU (*international units) which can help maintain sufficient blood serum levels of vitamin D. Unless you consume an unusual amount of oily fish products, diet alone cannot provide the levels of Vitamin D your body needs for optimal health.

For those with low levels, a maintenance dose of 1000IU is not enough. Adults require daily supplementation of 2,000 – 5,000IU (the higher end if you’re overweight) over an extended period to effectively increase the blood level above 30ng/mL, which is when immune function is typically restored.

“After supplementing and my patients’ vitamin D levels have returned to normal, their immunity improves, their mood lifts and they have more energy. There’s no doubt that having sufficient vitamin D levels improves their quality of life,” says Benita. 

If you suspect you have insufficient levels of vitamin D, it’s best to test, not guess, before taking a large dose (exceeding 800IU for adults, and 400IU for kids). While an insufficient level of Vitamin D3 can undermine your immunity and bone health, too much of this nutrient can cause side effects like nausea, vomiting, stomach pain and irregular bowel movements.

To confirm your Vitamin D3 levels, we recommend a blood test. Or, you can opt for a yearly health screening which includes vitamin D as part of your analysis.

Vitamin D is fat soluble, so when supplementing, it should be taken alongside a source of dietary fat (like yoghurt, avocado, olive oil or fatty fish) to boost absorption.

In summary

Most of us have low levels of vitamin D, which can impair bone and immune health. During the winter months, healthy adults can take a daily maintenance dose of between 600 and 800 IU. Kids can safely take 400IU.

Our naturopaths recommend Micellized Vitamin D3 by Klaire Labs (also known as SFI Health) provides adjustable dosing for the whole family.

For vegetarians, we recommend Twice Daily Multi by Designs for Health, a multivitamin which contains vitamin D3. Vegans can opt for Opti-Vita by Natroceutics, which contains vegan vitamin D3.

Around two thirds of the world’s population has low levels, and a dose larger than 800IU is needed to raise vitamin D levels adequately. Before taking a large dose, it’s important to test your levels of vitamin D, to make sure a supplement is right for your health needs. Using the data from your test, our naturopaths can recommend the right daily dose to optimise your vitamin D levels.

At IMI, our goal is to help you to achieve healthy blood levels of 30-50ng/mL so that your immune system can function at its best.

References
Bergman, Peter et al, Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials, 2013
Wang EW, Pang MY, Siu PM, et al. Vitamin D status and cardiometabolic risk factors in young adults in Hong Kong: associations and implications, 2018.
Biesalski HK, Vitamin D deficiency and co-morbidities in COVID-19 patients – A fatal relationship?, 2020
M Wacker, M F Holick, Sunlight and vitamin D, 2013.
A W Norman et al, 13th workshop consensus for vitamin D nutritional guidelines, 2008.
National Institutes of Health, Vitamin D.
Yale Medicine, Vitamin D Deficiency.
Met Office, Hong Kong weather.
A Rahman, A Elmi, Air pollutants are negatively associated with vitamin D – synthesizing UVB radiation intensity on the ground, 2021.
Royal osteoporosis society, Vitamin D: welcome to the ‘sunlight zone’, 2023.
S Baxi Srivastava, Vitamin D: do we need more than sunshine?, 2021.
R Heaney, Barriers to optimizing vitamin D3 intake for the elderly, 2006.