Why You Keep Getting Sick Every Winter (And What’s Actually Going On)

The three things missing from most people’s winter health plan, and how to fix them.

Every year around this time, I start seeing a familiar pattern in clinic.

Patients come in exhausted, a little run down, often fighting off their second or third cold for the season and start the cycle of getting sick every winter. They have been taking zinc since the first sniffle. They bought the elderberry syrup. They are doing what they think they are supposed to do.

But they keep getting sick.

And when we look a little deeper, the answer is almost always the same: the foundations were not in place before winter arrived.

The immune system is not a switch you flip when a cold comes on. It is a living system that requires consistent, year round nourishment. And in winter, when viral load is higher, temperatures drop, and we spend more time indoors, any gap in that foundation becomes very obvious very quickly.

So let me share what I actually look for when a patient keeps getting sick every winter.

In Chinese Medicine: It Begins with the Kidneys

The Winter Solstice marks the beginning of the Kidney season in Traditional Chinese Medicine. The Kidneys are considered the root of all Yin and Yang in the body. They house what we call Jing, our constitutional vitality, the deep reserves of energy we were born with and build through our lifestyle choices.

When Kidney energy is depleted, the body lacks the deep reserves it needs to mount a strong immune response. You might notice:

• Feeling cold all the time, especially in the lower back, knees and feet
• Deep fatigue that rest does not fully fix
• Recurrent illness or slow recovery
• Low motivation or that flat, grey feeling through winter
• Dark circles under the eyes

These are not separate complaints. In Chinese Medicine, they are all expressions of the same underlying depletion.

Warming and supporting Kidney Yang through the winter months is foundational. This means warm foods and drinks, protecting the lower back and feet from cold, adequate rest, and targeted acupuncture that builds Wei Qi, the protective energy that acts like a shield against external pathogens.

The Three Nutrients I Check in Almost Every Patient Who Keep Getting Sick every Winter

From a naturopathic perspective, there are three markers I look at before anything else when someone tells me they get sick constantly. They are not exotic. But most people are low in at least one of them, and most standard blood tests do not pick it up because they are looking at population reference ranges, not optimal ranges.

1. Vitamin D

Vitamin D is not really a vitamin. It behaves more like a hormone, and it plays a central role in regulating immune function. Without adequate Vitamin D, the immune system cannot mount an effective response to viral infection.

The standard reference range for Vitamin D in Australia is 50 nmol/L or above. But in clinical practice, I aim for 80 to 120 nmol/L for genuine immune resilience. At 55 nmol/L you are technically not deficient. But you are also no where near thriving.

In Melbourne, Vitamin D drops significantly through the winter months because UVB radiation is insufficient for skin synthesis between May and August. Anyone who lives below Sydney is affected, as the latitude affects the angle of the suns UVBs penetrating the atmosphere. This means supplementation is often genuinely necessary during this period, not optional.

2. Ferritin (Iron Stores)

Low iron is one of the most under-recognised contributors to immune dysfunction and chronic fatigue. Ferritin is the storage form of iron, and it is often within the normal range on a standard blood test while still being too low for optimal function.

I look for ferritin above 80 ug/L for women, and ideally above 100 ug/L. The population reference range often lists anything above 13 to 15 ug/L as normal. A patient sitting at 18 ug/L will be told their iron is fine. But at 18 ug/L, the immune system is struggling, the thyroid cannot convert hormones efficiently, and the mitochondria are not producing energy properly.

If you are tired every winter, catch everything going around, and feel slow to recover, your ferritin is worth investigating properly.

3. Zinc

Zinc is essential for the development and function of immune cells. It is directly antiviral and anti-inflammatory, and it is involved in over 300 enzymatic processes in the body.

Most Australians get some zinc through diet, but the amounts are often insufficient for immune support, particularly in people who are under stress, not eating much red meat, or relying heavily on plant-based sources (where zinc absorption is lower due to phytates).

Signs you may be low in zinc include: slow wound healing, white spots on fingernails, recurrent infections, loss of taste or smell, poor skin, and low appetite.

Zinc is best assessed through a plasma zinc test. And in clinic, I often find that even people with adequate dietary intake need short-term supplementation to bring levels up properly.

What You Can Do Right Now

Winter has just begun. That means you still have time to build your foundation before the worst of the cold and flu season hits in July and August.

Here is where I would start:

• Get your Vitamin D, ferritin and zinc checked through your GP and remember to get a copy of your results
• Start Vitamin D3 with K2 if you have not already (2000-4000 IU daily as a basic maintenance dose through winter)
• Eat zinc-rich foods daily: oysters, red meat, eggs, pumpkin seeds, legumes
• Drink warm fluids, especially bone broth, ginger tea, and miso soup
• Keep your lower back, neck and feet warm, especially in the morning
• Prioritise sleep: this is when immune memory consolidates and repair happens

A Note on Testing

One of the things I feel most strongly about in my practice is understanding the difference between a result that is technically normal and a result that is actually optimal.

If you have had blood tests recently and been told everything is fine but you still feel tired, run down, and under the weather, it is worth having someone look at those results through a functional medicine lens.

This is exactly what I do in a naturopathy consultation at Shine Health. We look at where your results actually sit within the range, not just whether they clear the minimum threshold.

If you would like to come in and talk through your winter health, you can book an appointment here: BOOK NOW

In the meantime

Stay warm. Nourish deeply. Your body knows exactly what to do when you give it what it needs.

xx Marta

Naturopath, Acupuncturist, and founder of Shine Health Wellbeing Centre

helping you Shine… from Inside Out