As winter drags on with its grey skies, short afternoons and steady stream of sniffles, many of us have felt our energy dip right along with the sunlight. It’s the season when vitamin D levels naturally fall and our immune systems work a little harder.

 

And with January’s familiar “new year, new me” momentum in the air, it’s the perfect moment to rebuild your defences and turn immune support into a simple daily ritual. 

Why Winter Leaves You Feeling Exposed

Cold, dark days send us indoors and away from the kind of direct sunlight our skin needs to make vitamin D. In the UK, winter sunshine simply doesn’t provide enough ultraviolet B (UVB) radiation for reliable vitamin D production. So just as seasonal bugs start circulating, our vitamin D levels tend to drift downward.

 

Because only a handful of foods naturally contain meaningful amounts of vitamin D (and they’re not everyday staples for most of us), many people find it difficult to maintain healthy levels through diet alone. This is why health experts recommend considering a daily supplement during autumn and winter to support normal bone, muscle and immune function.

Vitamin D: A Winter Upgrade for Your Immune System

Vitamin D plays a direct role in immunity. Immune cells such as macrophages and T cells have vitamin D receptors, meaning they rely on vitamin D to:

 

·      activate natural defence pathways

·      recognise pathogens effectively

·      keep inflammatory responses balanced

 

When vitamin D levels fall, the immune system may not respond as efficiently. Low levels don’t cause colds or flu, but they are associated with a higher likelihood of picking up seasonal bugs and taking longer to bounce back.

 

Keeping vitamin D topped up is one of the simplest, most researched ways to support everyday immune health, right alongside sleep, nutrition, hand washing and staying up to date with recommended vaccinations.

 

And because our bodies use vitamin D steadily - not in big bursts - a daily, moderate dose is often the most practical option through the darker months.

Foods That Provide Vitamin D

Although food alone may not maintain vitamin D levels in winter, adding naturally rich sources into your meals can help support overall intake:

 

1.   Oily fish: salmon, trout, sardines, mackerel
2.   Egg yolks
3.   Fortified foods:  cereals, plant milks, dairy alternatives
4.   Liver
5.   Mushrooms

These can complement whatever vitamin D support you choose during the low-sunlight months.

Lactoferrin: Protection at the Gateways

If vitamin D supports the immune system from within, lactoferrin works at the body’s front line.

Lactoferrin is a natural iron-binding protein found in saliva, tears and breast milk, places where the body protects its gateways. It has well established antibacterial and antiviral properties, helping to:

 

·      keep the mouth, nose and gut guarded

·      prevent unwanted microbes from attaching to cells

·      support balanced immune responses

 

Research suggests that taking oral lactoferrin helps maintain normal immune function, particularly during the colder months when we’re indoors more and seasonal bugs are everywhere.

It’s also a time when people are tired, run-down and keen to “start fresh”: the perfect moment to channel that motivation into something practical and empowering. Think: “new year, new defences”.

 

Leapfrog Remedies IMMUNE: Your Daily Winter Shield

Leapfrog Remedies IMMUNE brings powerful winter support together in one simple ritual: lactoferrin + zinc + vitamin C, designed to help your body's natural defences stay steady when winter takes its toll.

 

IMMUNE doesn't replace vitamin D, but it works alongside your vitamin D sources, whether that's sunlight, food or a supplement. It supports:

 

·      the body's natural defence barriers

·      normal immune function

·      a healthy, balanced immune response

 

It's an easy, tasty ritual that fits naturally into the season when your body needs support the most.

One simple trick? Take IMMUNE right after brushing your teeth. Linking it to an existing habit makes it far easier to stay consistent.

Turning Intention into Action

Here’s the January message in a nutshell: winter sun is weak, seasonal bugs are strong, and your defences deserve some support.

 

A daily combination of vitamin D and lactoferrin is a simple, proactive way to look after your wellbeing throughout the colder months. With ‘new days, new defences’ as your mantra, Leapfrog IMMUNE becomes your everyday winter shield.

 

Set a reminder. Build the habit. Keep your defences steady all season long.

 

 

Reference list

 

Aranow, C. (2011). Vitamin D and the immune system. Journal of investigative medicine : the official publication of the American Federation for Clinical Research, 59(6), pp.881–886. doi:https://doi.org/10.2310/JIM.0b013e31821b8755.

 

BBC Food. (2025). Which vital nutrient are nearly a third of us not getting enough of? [online] Available at: https://www.bbc.co.uk/food/articles/vitamin_d.

 

Jones, T. (2019). 7 Nutritious Foods That Are High in Vitamin D. [online] Healthline. Available at: https://www.healthline.com/nutrition/9-foods-high-in-vitamin-d#takeaway.

 

Kell, D.B., Heyden, E.L. and Pretorius, E. (2020). The Biology of Lactoferrin, an Iron-Binding Protein That Can Help Defend Against Viruses and Bacteria. Frontiers in Immunology, 11(1221). doi:https://doi.org/10.3389/fimmu.2020.01221.