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Latest Findings on Vitamin D and Immunity

Vitamin D, nicknamed the sunshine vitamin, has a key role in the immune system. Looking a the latest research on Vitamin D and immunity, we ask the questions, could vitamin D status be the reason some people only suffer mild symptoms while others get severely ill with infections?

Can you remember a time when you hardly ever discussed immunity with your friends and family? That may seem like a distant memory because immunity has become such a hot topic these days.

As the pandemic continues its path through our communities, it has become obvious that some people only suffer a very mild case while others become severely ill. This observation spurs on a lot of discussion on the topic of immunity.

A person’s nutritional status affects their immunity.

The physiology behind why some people are better placed to fend off pathogens is complex and multifaceted. One factor that has come to light over the last couple of years is how a person’s nutritional status affects their immunity.

In this Health Article, we’ll look at the role of nutritional status in immune health and in particular, the latest research on the role of Vitamin D on health outcomes through the pandemic.

Vitamin D, the Sunshine Vitamin

Vitamin D is a fat-soluble nutrient your body needs for many different functions. It’s needed for healthy bones because your body can only absorb calcium when vitamin D is present. It also regulates many other cellular functions, and it is particularly crucial for immune health.

Vitamin D has been nicknamed “the sunshine vitamin”, you get more from sun on your skin than from food.

Vitamin D has been nicknamed “the sunshine vitamin”. That’s because the bulk of it is obtained through your skin’s exposure to sunlight. Some foods contain low levels of vitamin D – such as oily fish, however the contribution from dietary sources is low compared to the amount of vitamin D generated by your skin in response to sunlight.

Vitamin D comes in two forms: vitamin D2 and vitamin D3. Both forms are effectively absorbed into the bloodstream, however studies show that vitamin D3 is much more effective than vitamin D2 at raising blood levels of calcifediol – the active form of vitamin D.

When choosing a vitamin D supplement, always look for vitamin D3, not vitamin D2.

When it comes to choosing a vitamin D supplement, always look for vitamin D3, not vitamin D2. Be assured, this is the only form of vitamin D that Xtend-Life uses. Kiwi-Klenz is no exception! It contains 1,000 International Units (IU or 25 micrograms) of vitamin D3 per serve for optimal benefits.

Immunity and Vitamin D status

According to a recent publication, vitamin D deficiency is now more prevalent than ever. In the United States, 61% of the elderly population are vitamin D deficient. This is a major problem, given the important role of vitamin D in immunity. 

It has long been known that vitamin D influences your risk of catching common colds and other respiratory infections.

  • Those with lower vitamin D levels are more likely to get a common cold,
  • Thosewho take vitamin D supplements are less likely to get a common cold.
  • Vitamin D supplementation also reduces the severity and duration of colds.

The latest findings on the role of vitamin D during the pandemic paint a very clear picture. In one recent study, called a meta-analysis, researchers found that data involving nearly 2 million adults showed that vitamin D deficiency clearly increases susceptibility to catching the virus and to developing more severe symptoms.

Another recent study from the pandemic backed up those results. The study showed that people with vitamin D deficiency were 14 times more likely to develop severe or critical illness and their mortality rate was also significantly higher (25.6% compared with 2.3% among those with sufficient levels of vitamin D).

To protect yourself from severe outcomes, you should aim to get sufficient vitamin D.

To protect yourself from severe outcomes, you should aim to get sufficient vitamin D. The most obvious source of vitamin D is from sunshine but the amount of exposure needed depends on where you live (distance from the equator), the season and your skin tone. For many people, getting enough sun is simply not practical either due to the season or spending a lot of time indoors.

To ensure you are getting sufficient vitamin D, consider a supplement such as Kiwi-Klenz which contains 1,000 IU (or 25 micrograms) per serve.

How Much Vitamin D do I Really Need?

Wouldn’t it be great if there were a simple answer! Unfortunately, there isn’t. The amount of Vitamin D you need depends on your age, ethnicity, sun exposure, the season and latitude where you reside.

The National Institutes of Health in the US recommends 400 international units (IU or 10 micrograms) of Vitamin D for children up to 12 months, 600 IU for people aged 1 to 70 years, and 800 IU (or 20 micrograms) per day for people over the age of 70 years. However, many experts believe this recommendation is too low.

The amount of Vitamin D you need depends on your age, ethnicity, sun exposure, the season and latitude where you reside.

You can measure your vitamin D status through a simple blood test. Depending on who you ask, blood levels between 20ng/ml and 30ng/ml are considered sufficient.

Studies in postmenopausal women with low vitamin D levels found that ingesting 800 – 2,000 IU vitamin D raised blood levels to the lower end of “sufficient”. However, higher doses were needed to reach the higher end of “sufficient”. People who are overweight or are obese may also need higher amounts of vitamin D to achieve sufficient blood levels.

If a blood test doesn’t appeal, all things considered, a daily vitamin D intake of 800 – 4,000 IU (or 25 – 100 micrograms) should be enough for most people.

According to the National Institutes of Health, the safe upper limit of Vitamin D intake is 4,000 IU (or 100 micrograms). However, research conducted in a hospital over a seven-year period showed that long-term supplementation with vitamin D3 in doses ranging from 5,000 to 50,000 IU/day appears to be safe. A separate study, individuals who took doses of vitamin D3 over several years with doses of 10,000 – 60,000 reported no safety concerns or side effects.

Studies in which people take high doses of vitamin D3 (over 10,000 IU) are usually done in the context of wanting a treatment for an autoimmune disorder, such as psoriasis or rheumatoid arthritis. In fact, at high doses, Vitamin D3 inhibits the immune system, hence dampening down the body’s autoimmune response.

If you’re considering a daily dose of vitamin D above 4,000 IU (or 100 micrograms), we recommend you check with your health professional first.

Should I take Kiwi-Klenz or Immu-Stay?

Our newly reformulated Kiwi-Klenz is designed to provide digestive support through its unique combination of prebiotics and L-Glutamine. The prebiotic fibres in Kiwi-Klenz, from green and gold kiwifruit are clinically proven to support a healthy microbiome, to reduce digestive discomfort, and to assist in the digestion of proteins.

With the addition of vitamin D3 and vitamin C, Kiwi-Klenz also provides support for your immune system. Kiwi-Klenz is designed to be taken daily for long term support. For those who are primarily looking for digestive support, Kiwi-Klenz is your best choice, and you get the added benefit of immune support.

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Immu-Stay on the other hand, is a potent blend of natural ingredients that is designed to give the immune system a big boost when needed, for example through the winter months. Immu-Stay is not designed to support digestive health. Instead, it is formulated with research-backed ingredients that are shown to reduce the duration and/or severity of winter ills and chills.

Immu-Stay is designed to be taken at the acute onset stage, or when there is elevated risk of exposure to pathogens for an immediate and powerful immune system boost. For those looking for fast, strong support, for example during an acute onset, Immu-Stay is your best choice.


McCullough PJ, et al. Daily oral dosing of vitamin D3 using 5000 TO 50,000 international units a day in long-term hospitalized patients: Insights from a seven year experience. J Steroid Biochem Mol Biol. 2019 May;189:228-239.

McCullough P, Amend J. Results of daily oral dosing with up to 60,000 international units (iu) of vitamin D3 for 2 to 6 years in 3 adult males. J Steroid Biochem Mol Biol. 2017 Oct;173:308-312.

Amon U, et al. Safety Data in Patients with Autoimmune Diseases during Treatment with High Doses of Vitamin D3 According to the "Coimbra Protocol". Nutrients. 2022 Apr 10;14(8):1575. 

Sizar O, et al. Vitamin D Deficiency. [Updated 2022 Jul 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.

Dror AA, et al. Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness. PLoS One. 2022 Feb 3;17(2):e0263069.

Weir EK, et al. Does vitamin D deficiency increase the severity of COVID-19? Clin Med (Lond). 2020 Jul;20(4):e107-e108. 

Martineau AR, Cantorna MT. Vitamin D for COVID-19: where are we now? Nat Rev Immunol. 2022 Jul 22:1–2. 

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