Vitamin D — More Than Just Sunshine

Vitamin D is a little unusual because your body can actually make it in your skin when it is exposed to sunlight.

Its best-known job is helping your body absorb and use calcium, which is important for maintaining strong bones. Vitamin D also plays roles in normal muscle and immune function.

Where do we get it?

For Australians, sunlight is usually the main source. Food contributes smaller amounts, with sources including:

• oily fish such as salmon and sardines

• eggs

• vitamin-D-fortified foods such as some milks and margarine

• UV-exposed mushrooms

Getting enough from food alone can be difficult for some people.

Why can levels vary?

How much vitamin D your body produces can depend on the season, where you live, how much time you spend outdoors, how much skin is exposed and your skin tone. In southern parts of Australia, winter can make vitamin D production more difficult.

And this is where supplementation can sometimes make sense.

If someone has low vitamin D or is at increased risk of deficiency, a health professional may recommend a supplement. That doesn’t mean everybody needs one — and deliberately spending excessive time in the sun isn't the answer either because UV exposure increases skin-cancer risk.

Iron — The Oxygen Carrier

Iron has one particularly important job: it helps your body make haemoglobin, the protein in red blood cells that carries oxygen around your body.

But iron is a great example of why where a nutrient comes from can matter.

There are two main types of iron in food:

• Haem iron — found in meat, poultry and seafood. Your body generally absorbs this form more easily.

• Non-haem iron — found in foods such as beans, lentils, chickpeas, tofu, nuts, seeds and leafy green vegetables. Your body can still use it, but absorption is generally lower.

And here is where nutrition gets interesting:

Vitamin C can help your body absorb more non-haem iron. So something as simple as combining lentils or beans with capsicum, tomatoes, citrus fruit or other vitamin-C-rich foods can improve how much iron becomes available to your body.

So once again, the question isn’t only:

“Does this food contain iron?”

It is also:

“What form is it in, and how well can my body absorb it?”

Vitamin B12 — Blood, Nerves and DNA

Vitamin B12 has several important jobs. It helps your body produce healthy red blood cells and supports the normal functioning of your nervous system.

Unlike many nutrients, B12 is found naturally mainly in animal-derived foods such as:

• meat and seafood

• eggs

• milk, yoghurt and cheese

Some plant-based foods are fortified with B12, but people following a vegan diet need to pay particular attention because reliable natural plant sources are very limited.

And B12 gives us another good example of why absorption matters.

Getting enough B12 into your diet is only part of the story. Your digestive system also has to release it from food and absorb it properly. Age, some gastrointestinal conditions, surgery and certain medicines can make that more difficult.

So with B12, the question again becomes:

“Am I consuming enough?”

but also:

“Am I actually absorbing enough?”

Fibre — More Than Just Keeping You Regular

Fibre is the part of plant foods that your digestive system doesn’t fully break down. Instead, it travels through the gut where it helps support healthy bowel function, stool consistency and regularity, while some types also feed beneficial gut bacteria.

One of fibre’s most noticeable jobs is helping bowel movements stay soft, formed and easier to pass. A low-fibre diet can contribute to constipation, while adequate fibre, fluids and regular movement all help support normal bowel function.

But “regular” doesn’t mean everybody has to go once every morning at 7:03 😂. Normal bowel frequency varies considerably between people. What matters more is that bowel movements are reasonably consistent for you, comfortable and easy to pass.

Where do we get fibre?

Good sources include:

• vegetables and fruit

• beans, lentils and chickpeas

• wholegrains

• nuts and seeds

And fibre isn’t all the same. Soluble and insoluble fibres behave differently in the digestive system, which gives us another great example later of why the type of an ingredient matters, not just the number on the label.

The Why Bit: Fibre doesn’t just “make you poo”. It helps influence how material moves through the gut, the consistency of your stool and even what some of your gut bacteria have available to feed on.

Vitamin C — More Than Immune Support

Vitamin C is probably best known for its connection with the immune system, but it has several other important jobs too.

Your body uses vitamin C to help support:

• normal immune function

• collagen formation, which is important for skin, bones, blood vessels and wound healing

• antioxidant protection

• iron absorption, especially the non-haem iron found in plant foods

Where do we get it?

Good sources include:

• capsicum

• broccoli

• kiwi fruit

• strawberries

• oranges and other citrus fruits

• Brussels sprouts

Vitamin C is also sensitive to storage and cooking, so the amount in food can change depending on how it is handled and prepared.

The Why Bit

Your body doesn’t manufacture vitamin C, so it has to come from your diet regularly.

Vitamin C also shows how nutrients can work together rather than acting alone.

Iron may be on the plate — but vitamin C can help your body make better use of it.

Zinc — Small Mineral, Big Job

Zinc is a mineral your body needs for a surprising number of everyday functions. It helps support normal immune function, skin health, wound healing, cell growth and division, and your senses of taste and smell.

Where do we get it?

Good food sources include:

• oysters and other seafood

• red meat and poultry

• eggs and dairy foods

• wholegrains

• legumes

• nuts and seeds

Your body generally absorbs zinc more easily from animal-based foods than from plant-based foods, which makes zinc another good example of why the amount in the food isn’t the whole story.

The Why Bit

Your body can’t make zinc, so you need to get it through your diet.

And because zinc is involved in things like immune function, skin repair and normal cell growth, getting enough matters even though the amounts required are relatively small.

Sometimes the nutrients we need in the smallest quantities are doing some very important jobs.

Magnesium — The Quiet Workhorse

Magnesium is a mineral involved in hundreds of processes in the body. It helps your muscles and nerves work properly, supports normal energy production, contributes to healthy bones and plays a role in blood sugar regulation.

Where do we get it?

Good food sources include:

• leafy green vegetables

• legumes

• nuts and seeds

• wholegrains

• some seafood

• smaller amounts in meat and dairy foods

Why can intake vary?

Magnesium is spread across many different foods, so how much you get can depend heavily on the variety of your diet.

Some digestive conditions, certain medicines and increasing age can also affect magnesium levels or absorption.

The Why Bit

Magnesium doesn’t usually get the attention that vitamin C or iron does, but it is constantly involved behind the scenes.

Muscles, nerves, energy production and bone health all rely on it doing its job.

Biotin — Small Vitamin, Important Chemistry

Biotin, also known as vitamin B7, helps enzymes in your body process carbohydrates, fats and some amino acids. In simple terms, it helps your body turn parts of the food you eat into forms it can use.

Where do we get it?

Biotin is found in a range of foods, including:

• eggs

• meat and liver

• fish

• nuts and seeds

• some cereals and plant foods

Most people get enough biotin from a varied diet, and true deficiency is uncommon.

What about hair, skin and nails?

This is where biotin gets heavily marketed.

Biotin deficiency can cause problems such as hair loss, skin changes and brittle nails, but that does not automatically mean taking extra biotin will improve hair, skin or nails in someone who already gets enough. Evidence for that common supplement claim is still limited.

The Why Bit

Biotin is a good example of the difference between:

“Your body needs this nutrient”

and

“More of this nutrient must be better.”

Your body definitely needs biotin — particularly for normal nutrient metabolism — but extra supplementation is most relevant when there is an actual need or dietary gap.

One useful little fact for later: high-dose biotin supplements can interfere with some blood-test results, including certain hormone tests, so this is one nutrient where “more” can also complicate things.

Chromium — Helping Insulin Do Its Job

Chromium is a trace mineral, which means your body only needs very small amounts of it.

Its best-known role is its involvement in insulin action and the metabolism of carbohydrate, fat and protein. In simple terms, chromium helps support the way insulin works as your body manages glucose after you eat.

Where do we get it?

Chromium is found across a range of foods, but the amount can vary quite a bit depending on the food itself and even where it was grown or produced.

Sources can include:

• wholegrains

• meat

• some vegetables

• nuts

• some fruits

• brewer’s yeast

Australia and New Zealand set an Adequate Intake for chromium rather than a firm recommended daily intake because the available evidence is still limited.

Why is chromium interesting?

Only a small percentage of the chromium we eat is actually absorbed, and absorption can vary depending on the food and what is happening in the digestive tract.

That makes chromium another good example of the theme we’ve been building through this page:

what is present in the diet is not always the same as what the body ultimately absorbs and uses.

The Why Bit

Chromium often gets marketed as though it is some kind of magic blood-sugar ingredient.

It isn’t.

Its real story is much more interesting: it appears to help support normal insulin action and nutrient metabolism, but taking more chromium does not automatically mean better blood-sugar control, and research on high-dose chromium supplementation has produced mixed results.

Tiny nutrient. Small amounts needed. But an interesting role in how the body handles the fuel we eat.

Vitamin A / Beta-Carotene — Your Body Can Make What It Needs

Vitamin A is important for normal vision, immune function, skin and the healthy growth and development of cells. It is especially well known for helping your eyes function properly in low light.

What makes this nutrient particularly interesting is that vitamin A can reach your body in two different ways.

Where do we get it?

Preformed vitamin A is found mainly in animal foods such as:

• liver

• eggs

• dairy foods

• some fish

Plant foods provide compounds called provitamin A carotenoids, including beta-carotene. Good sources include:

• carrots

• pumpkin

• sweet potato

• spinach and other dark leafy greens

• some orange and yellow fruits and vegetables

Here’s the interesting bit

Beta-carotene isn’t actually vitamin A yet.

Your body can convert beta-carotene into vitamin A, and that conversion is regulated partly according to your vitamin A status. In other words, the orange pigment in a carrot can become a vitamin your eyes, immune system and cells can use.

And because vitamin A is fat-soluble, eating beta-carotene-rich vegetables as part of a meal containing some dietary fat can help with absorption.

The Why Bit

Carrots really can contribute to eye health — but they won’t give you superhero night vision 😂.

Their beta-carotene provides your body with a raw material that it can convert into vitamin A, which is needed for normal vision.

Sometimes the nutrient on your plate isn’t even in its final form yet — your body has to finish the job.

And What About Hormones?

Hormones don’t operate in isolation from nutrition.

Your body needs nutrients to carry out thousands of chemical reactions, including processes involved in making, activating, transporting and responding to hormones.

That doesn’t mean eating one particular vitamin will simply “balance your hormones”. The relationship is much more complex than that.

But it does mean that nutrition, hormones and the way your body functions are connected.

And some nutrients have particularly interesting relationships with specific hormone systems.

That’s a Why Bit worth coming back to.