INL Articles - Vitamin D Deficiency

Vitamin D in Hong Kong...The Elephant in the Room

Vitamin D Is Shown To Protect You From Common Cold and Winter Coughs, Especially If Your Levels Are Low (and they most likely are sub optimal)

Vitamin D has important health effects far beyond benefits to the bones. Not only is vitamin D3 known to help reduce your risk of osteoporosis, rickets, or bone fracture, scientists have found about 3,000 genes that are responsive and triggered by vitamin D3. Vitamin D3 improves immunity, especially to upper respiratory tract infections.(1)

For the lungs and sinuses Vitamin D3 works mostly by improving our levels of secretory IgA, which is the first line of immune defence against viruses and bacteria.

Vitamin D, the sunshine vitamin, is needed for full immunity. Vitamin D levels are lowest in winter, and is partly why susceptibility to coughs, colds and flu is a winter phenomenon. In a study of UK adults, the prevalence of respiratory infections had a strong seasonal pattern in the opposite direction to the pattern for vitamin D3 blood concentrations. (2

Vitamin D, the “sunshine vitamin” because the main way to get it is through exposing your bare skin to sunlight. In Hong Kong, during winter we would need approximately 45 minutes of exposure on the arms, legs, face, and hands every second day in winter to produce adequate levels of vitamin D. 

In the northern Hemisphere, February is the month of the lowest levels of vitamin D3 found across all ages, owing to the lack of time spent out in the sun in winter. 

Each 2.5ng/mL increase in vitamin D was associated with a 7% lower risk of infection.(2) The UK study showed vitamin D status had a direct linear relationship with respiratory infections and better lung function. Other studies have shown those with optimal blood levels (over 30 ng/mL) over winter get approximately 40% less upper respiratory tract infections. 

A 2018 study of 196 young Hong Kong adults showed average vitamin D concentration was 13ng/mL, being near the deficiency level. 72% of these Hong Kong subjects had vitamin D deficiency - defined as <20ng/mL; and 6.6% were severely deficient (<10ng/mL).(3

Unfortunately, very few foods in nature contain vitamin D. 

The flesh of fatty fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. Cod liver oil is the best food source.

We see small amounts of vitamin D are found in beef liver, cheese, and egg yolks. Mushrooms with enhanced levels of vitamin D2 from being exposed to ultraviolet light under controlled conditions are also available. 


Does supplementation of vitamin D3 help correct this seasonal trend? 

Yes, studies on this do show a positive effect, and daily dosing is most effective. 

In a 2013 study vitamin D supplementation showed a protective effect against respiratory tract infection (with an odds of 0.64 or a 36% reduction). The protective effect was larger in studies using once-daily dosing compared to bolus (one off) doses. Given as daily doses the odds ratio dropped to  0.51 of getting a respiratory infection, i.e. a 49% decrease in incidence.(4)

Another study showed regular Vitamin D supplementation reduced the risk of acute respiratory tract infection (URTI) among all participants (adjusted odds ratio in those receiving daily or weekly vitamin D was 19% less on average, ranging up to 28% less frequent URTI’s in a meta-study published in the British Medical Journal in 2017). The study with high quality evidence concluded: “Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus (one off) doses experienced the most benefit.”(5)


Is there evidence that Vitamin D3 supplementation for those with low blood levels can support those with chronic lung conditions as well? 

Yes. A Lancet article showed: “Vitamin D supplementation safely and substantially reduced the rate of moderate to severe COPD (chronic obstructive pulmonary disease) exacerbations (by 45%) in patients with baseline 25-hydroxyvitamin D levels less than 25 nmol/L (10 ng/mL), but not in those with higher levels.”(6) Note these levels of vitamin D are very low, but not uncommon in winter.

The benefit also extends to asthma sufferers: “Vitamin D supplementation reduced the rate of asthma exacerbation requiring treatment with systemic corticosteroids among all participants” ” The adjusted incidence rate ratio was 0·74, among 955 participants in seven studies; high-quality evidence. In those with blood levels under 25nmol/L (10 ng/mL), and taking daily steroid puffers as well, protective effects of vitamin D supplements were strongest - with a relative risk of just 0·33, (or 67% less serious asthma incidents) in 92 participants in three studies.(7


Does Intake of 25-Hydroxyvitamin D3 Reduce Duration and Severity of Upper Respiratory Tract Infection?

Yes. Even just 400IU for 16 consecutive weeks showed “the total physical severity score and the total quality of life score during the study both were significantly improved in the vitamin D group compared to placebo”. The study concluded vitamin D supplementation – even at these low levels of supplementation for an adult population – “may reduce the duration of URTI, the physical severity, and the quality of life when suffering from URTI.”(8)

Are Low Vitamin D blood levels associated with higher cytokines TNF-a or IL-6.

Yes. Serum levels of Vitamin D have been reported to be inversely related to serum IL-6 and TNF-a levels in many studies.(9) The optimal daily dosages are unlikely to foster a “cytokine storm’.

Do You Have An Adequate Level of Vitamin D if you are supplementing with a multivitamin?

A study in 2011 in the United States delivered a shocking result. This study involved over 3,000 volunteers who despite taking regular daily vitamin supplements, 90% were still sub optimal in vitamin D. 

Most daily multi vitamins do not provide sufficient to meet optimal needs, and in Hong Kong laws limit the per tablet or dose delivery to 1,000IU. This is inadequate to raise a low vitamin D blood level efficiently if starting from the commonly low levels between 10-20ng/mL (remember the Hong Kong average for young men is 13ng/mL).  

Our IMI blood studies show nearly all blood initial samples from our clients are suboptimal in vitamin D, just as found in these published study results. Our aim is to get blood levels near to 50ng/mL. Most vitamin D lab reports now recommend blood levels of 30 to 60ng/mL as sufficient (or 75-150nmol/L).


INL’s Supplement Recommendations

Based on research studies, INL Founder Graeme Bradshaw recommends daily doses of 600 – 800 IU for infants under 18months, given daily. Review the extra amounts given in formula feeding. Both the United States and Canada mandate the fortification of infant formula with vitamin D: 40–100 IU/100 kcal in the United States and 40–80 IU/100 kcal in Canada, and the ranges are similar here. If supplementing infants with extra vitamin D, take the amounts in formulas or dairy products into account. Over 1,500IU in infants is potentially harmful taken over longer periods.

Breast feeding mothers, unless taking vitamin D supplements provide little to their infants. Breast feeding mothers can provide sufficient with 4,000IU according to Professor Holick, the world expert.

The US recommended daily allowance for Vitamin D is currently set at 400-800IU/day, but this is too low for adults to elevate low levels. 

The safe upper limit in the United States and Canada is currently at 4,000IU/day. 

Research suggests that the true safe upper limit is 10,000IU/day. For moderate supplementation, a 1,000 - 2,000IU dose of vitamin D3 is sufficient to meet the needs of most of the population. This is the lowest effective dose range. 

Higher doses, based on body weight, are in the range of 20-80IU/kg daily.

Vitamin D3 supplementation (cholecalciferol) is recommended over D2 supplementation (ergocalciferol), since D3 is used more effectively in the body.

Vitamin D should be taken daily, with meals or a source of fat, like fish oil.


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