The Importance of Vitamin D - and How it Works with Your Body

These days, we’re more aware than ever of the importance of protecting our skin from the sun. We wear sunscreen, reach for a sunhat, cover up and seek shade, particularly during the warmer months. While these habits are important for protecting our skin, they also mean we may get less sunlight on our skin than we once did.

That becomes even more relevant during winter, when shorter days, cooler temperatures and more time spent indoors can further reduce our exposure to sunlight.

That matters when it comes to vitamin D.

Vitamin D is sometimes called the "sunshine vitamin" because our bodies can make it when our skin is exposed to UVB radiation from sunlight. How much we produce depends on a number of factors, including the season, where we live, our skin tone, how much skin is exposed and how much time we spend outdoors.

In parts of New Zealand with lower levels of sunshine, such as the lower South Island and West Coast, winter can make it harder for some people to maintain adequate vitamin D levels.

So, whether it’s the amount of time we spend indoors or simply how we protect ourselves from the sun, it’s worth understanding what vitamin D actually does, where we get it from, and how it fits into the bigger picture of nutrition and gut health.

What is vitamin D?

Vitamin D is a fat-soluble vitamin, which means it can be stored in the body's fatty tissues and liver.

Unlike most vitamins, however, your body can make vitamin D itself. When your skin is exposed to UVB radiation from sunlight, it starts a process that eventually produces vitamin D3. Vitamin D obtained through food and supplements comes in two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

Both forms need to go through further processing in the liver and kidneys before they become the active forms your body can use.

Vitamin D is particularly important because of its relationship with calcium. It helps your body absorb calcium from the food you eat and plays an important role in maintaining normal bones and teeth.

It is also involved in normal muscle function and the functioning of the immune system.

In other words, vitamin D is doing much more than simply supporting your bones.

Can you get vitamin D from food?

Yes. While sunlight is an important source of vitamin D, you can also get it from certain foods. The catch is that there are relatively few foods that naturally contain significant amounts.

Some of the better dietary sources include:

• Fatty fish such as salmon, sardines, anchovies and mackerel
• Cod liver oil
• Egg yolks
• Beef Liver
• Mushrooms
  

For most people, food can make a useful contribution to vitamin D intake, but it can be difficult to get enough from diet alone. Unlike nutrients such as vitamin C, which are found across a wide range of everyday foods, vitamin D is naturally present in a much smaller selection.

That doesn't make a varied diet any less important. Eating a good range of whole foods helps provide the many different nutrients your body needs, rather than putting the focus on any one nutrient in isolation.

Vitamin D, calcium and healthy bones

One of vitamin D's best-established roles is helping the body absorb calcium.

Calcium is essential for maintaining bones and teeth, as well as supporting normal muscle and nerve function. Vitamin D helps regulate calcium in the body, which is why the two nutrients are often discussed together.

This is also why vitamin D becomes particularly important as we get older.

The recommended dietary intake for vitamin D increases with age, from 5 micrograms per day for adults aged 1–50, to 10 micrograms for those aged 51–70 and 15 micrograms for adults over 70.

If you think you may be low in vitamin D, it is worth speaking with your doctor rather than simply taking a high-dose supplement. More is not necessarily better, and excessive vitamin D supplementation can cause problems.

What does vitamin D have to do with gut health?

This is where things get interesting.

Your gut is involved in far more than digestion. The gastrointestinal tract is home to a complex community of microorganisms, collectively known as the gut microbiome, and researchers are increasingly interested in the relationship between the gut microbiome and other aspects of nutrition and health.

Vitamin D and the gut microbiome appear to have a relationship too.

Research in humans has found associations between vitamin D status, vitamin D supplementation and changes in gut microbiome composition. However, the evidence is still developing, and studies have produced varied results. Researchers are continuing to investigate whether vitamin D influences the microbiome, whether the microbiome influences vitamin D metabolism, or whether the relationship works in both directions.

There has also been research looking at combining vitamin D and probiotics. Some clinical trials have reported potentially beneficial outcomes from co-supplementation, but the studies have been relatively small and have looked at different populations and health outcomes. More research is needed before we can draw broad conclusions, however as vitamin D and the gut microbiome are an area of ongoing scientific research, we believe it is worth looking at nutrition as a whole.

Supporting your gut with whole foods

At Immunity Fuel, we have always taken the view that gut health is about more than a single supplement.

A varied diet provides fibre, vitamins, minerals, healthy fats and other nutrients, while fermented foods can add beneficial microorganisms to the diet.

This is where a fermented probiotic food like Immunity Fuel can fit naturally into your daily routine.

Immunity Fuel is made using a traditional fermentation process with organic wholefood ingredients and a culture of beneficial bacteria and yeasts. The result is a shelf-stable fermented probiotic powder that can be added to everyday foods.

We don't see it as a replacement for a nutritious diet. Quite the opposite.

It's an easy way to add fermented probiotic food to things you're already eating, whether that's a smoothie, yoghurt, dressing or breakfast bowl.

And because it is a food rather than something that needs to be treated like a medicine, it can be incorporated into your routine in simple, everyday ways.

SHOP IMMUNITY FUEL

RECIPE: A vitamin D-rich meal with probiotic dressing

One of our favourite ways to think about nutrition is to put the pieces together on the plate.

This simple mushroom and tomato omelette brings together eggs and mushrooms, two foods that can contribute vitamin D to your diet, along with leafy greens, seeds and a probiotic-rich Immunity Fuel dressing - yum!

It makes an easy breakfast or lunch and is a delicious reminder that supporting your nutrition doesn't have to be complicated.