Vitamin D and Gut Health: What Your Body Needs in Winter

Winter has a way of changing our daily routines. We spend more time indoors, rug up when we do head outside, and those long, sunny days of summer can feel like a distant memory.

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. But how much vitamin D 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 Australia, particularly the southern states, winter can make it harder for some people to maintain adequate vitamin D levels.

So, as we move through the cooler months, it is 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, although there are relatively few foods naturally rich in vitamin D.

Some of the better dietary sources include:

• Oily fish such as salmon, sardines, anchovies and mackerel
• Egg yolks
• UV-exposed mushrooms
• Some fortified foods, including certain milks and margarines

In Australia, vitamin D is present in some foods, but it can be difficult to obtain all the vitamin D you need from food alone.

This is one reason vitamin D is an interesting nutrient. Unlike vitamin C or many of the B vitamins, there aren't dozens of everyday foods that provide substantial amounts.

A varied diet still matters, though. Rather than focusing on one nutrient in isolation, it makes sense to look at the overall quality and variety of the foods you're eating.

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 Australian recommended dietary intake for vitamin D increases with age, from 5 micrograms per day for adults aged 19–50, 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 ORIGINAL

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.

Veggie Omelette with Immunity Fuel Probiotic Dressing

Serves: 1–2

Ingredients

For the omelette

2 eggs, beaten
2 mushrooms, sliced
4 cherry tomatoes, halved
1 bunch kale
2 tbsp sesame seeds
Olive oil
Salt and pepper

For the probiotic dressing

½ cup plain yoghurt or coconut yoghurt
¼ cucumber, finely diced
1 tsp Immunity Fuel Original powder
Fresh coriander, chopped
Salt and chilli flakes, to taste
1 tsp lemon juice

Method

Preheat the oven to 150°C.

Place the kale and sesame seeds on a baking tray. Drizzle with olive oil and season with salt and pepper. Bake for approximately 10 minutes, until the kale is crisp.

Meanwhile, heat a little olive oil in a non-stick pan over medium-low heat. Add the mushrooms and tomatoes and cook for a few minutes until softened. Remove from the pan and set aside.

Add a little more olive oil to the pan. Pour in the beaten eggs and allow them to cook without stirring until the edges begin to set.

Add the cooked mushrooms and tomatoes and continue cooking until the omelette is set.

For the dressing, simply combine the yoghurt, cucumber, Immunity Fuel Original, coriander, lemon juice and seasonings. Stir well.

Serve the omelette with the crispy kale and sesame seeds, with the probiotic dressing on the side.

Recipe by Nancy Poole, Nutritionist