You can feel it in the air: temperatures dropping, leaves crisping, nights drawing in. It seems like we blinked and summer was over, and now a new season begins.
But as we return to our desks and dig out the jumpers, it’s not just the weather that’s turning, our bodies are going through changes too.
Whether you’re in need of a post-summer reset or preparing for the colder months ahead, let’s take a look at the most important nutrients to help you thrive as autumn arrives.
First up: what summer took out of us
We tend to think of summer as the healthy (and happier) season: more sunshine, more fun, more movement, more time outdoors.
In fact, a 2019 study by Cornell University dug into Spotify data and found that people living in countries with longer, sunnier days listen to more energetic, upbeat music than those with shorter, darker days.
But summer takes its toll on our bodies, often more than we realise. Hot weather and excessive sweat can deplete our stores of vitamins and minerals. And as social plans take over, it’s easy to let balance slide.
If any of that sounds familiar, your body might already be running on lower reserves. And that’s before it needs to meet the demands of a new season…
Six things that happen to your body in autumn
Research shows a whole range of physical and behavioural shifts as we transition from summer into autumn, some of which you might recognise…
Drowsiness and fatigue
If you keep getting hit by waves of tiredness, it’s all down to your circadian rhythm: the internal “clock” that regulates your sleep, hormones, body temperature, and more.
Research suggests that the “in-between” season of autumn can be particularly rocky as your body adjusts to reduced daylight: one study tracking sleep across the seasons found that duration was measurably shorter in autumn compared to winter.
In other words, it’s not just you who’s shocked to see that it’s already dark outside, your circadian rhythm gets nudged out of sync, and it takes a while to settle back down again.
Mood
There’s another reason you might start to feel sluggish in September: along with the leaves, your serotonin levels can start to fall.
Serotonin production is triggered by sunlight, and this hormone plays a key role in mood, calm, and focus. Studies suggest that this could be a key reason why people suffer from seasonal affective disorder (SAD): brain imaging has shown significant seasonal differences in the way their neurotransmitters regulate serotonin, compared to those who don’t get the winter blues.
Vitamin D, which our bodies naturally produce from sunlight, is thought to support serotonin production too (it’s common for people with SAD to have a vitamin D deficiency).
Cold and flu
If you’ve only just recovered from summer allergies, you might not be thrilled that we’re heading into another season of sniffles.
It’s widely assumed that autumn and winter colds are a result of being cooped up indoors, near other people’s germs. However, researchers found a more direct explanation: colder air actively suppresses a protective immune response inside the nose—the first real biological mechanism we’ve discovered that explains why infections spike as temperatures drop.
Digestive issues
Summer can have a mixed effect on our digestive systems. On the one hand, increased alcohol intake, travel, and variations in diet (we’re looking at you, hotel buffet) can disrupt your gut microbiome.
On the other hand, summer usually means more incidental movement - walking instead of driving, being upright and outside more, which matters to gut health more than you'd think. One study found that just 20 minutes of walking measurably picked up gut motility within a couple of minutes, and that low activity is a contributor to slower digestion.
Dry or damaged skin
That tightness across your cheeks isn't your imagination. Changes to humidity and temperature levels mean your skin has to work harder to hold onto moisture, which can cause dryness in the cooler months. And if your skin barrier is also recovering from a summer of soaking up those rays, it might need some extra TLC.
Bone health
A combination of reduced sunlight exposure, lower vitamin D levels, and a drop in physical activity can also affect bone density during the colder months.
Research shows that bone density hits its lowest point in winter, particularly for women as they age, and in one trial, giving people vitamin D3 and calcium through the colder months reversed the pattern entirely. A good reminder that vitamin D's job goes far deeper than just mood and immunity.
So, how can you support your body through these shifts?
The nutrients your body needs right now
To keep your body strong and healthy for autumn and beyond, make sure you’re filling any nutritional gaps that may have emerged after a draining summer, or as darker, colder weather sets in.
Here are some of the most important nutrients your body needs right now:
Vitamin D for mood, immunity and bone health
Thinking that a sunny summer means you’ve topped up your vitamin D for the rest of your year? It doesn’t quite work like that.
One study following almost 300 people across Northern England found that vitamin D levels stayed low all year round among groups most at risk (for example, older adults and those with darker skin), even after a summer of sun.
It's why the NHS recommends taking a daily supplement from October to March.
Magnesium for sleep, mood and whole-body health
Magnesium is one of the most important minerals for your general health, essential to everything from producing enough energy to keeping your heart ticking.
If you’re prone to the winter blues or find yourself nodding off at your desk, magnesium plays a key role in sleep and stress. It also supports muscle recovery, which is handy if you’re keen to keep up those fitness levels all year round.
Since heat and sweat deplete your magnesium levels, autumn is a good time to consider replenishing those reserves.
Collagen for hydrated, healthy skin
Spent lots of time outside this summer? It’s worth noting that the sun does more than tan your skin: the enzymes that break down collagen activate within minutes of UV exposure, and stay elevated for hours afterwards.
You won’t notice any visible effects right away, but this sun damage builds cumulatively. If seasonal dryness is also making your complexion look lacklustre, a high-quality vegan collagen supplement can support the rebuilding process.
Omega-3 for joint health and brain function
Omega-3s are best known for their anti-inflammatory role, which is part of why they're often linked to joint comfort as colder weather returns and you tend to feel stiffer.
DHA, one of the two main omega-3 fats, is also a major structural component of the brain, supporting the clear thinking you need for back-to-work mode.
Zinc & selenium for immunity
As cold and flu season creeps closer, this pair makes for a dynamic duo. In pooled clinical data, zinc cut the duration of cold symptoms by 42% compared to placebo, and it works even better alongside selenium—a shortfall in either raises oxidative stress and lowers immune response. If you're looking to top up through a plant-based diet, nuts and seeds are rich in both.
Fibre & iron for energy and digestion
If summer involved more breadsticks than salads, upping your fibre intake will keep digestion smooth and energy levels steady.
Speaking of energy, iron and vitamin B6 are cornerstones of your metabolism—helping with that "why am I always tired?" feeling that’s so common as the seasons turn.
The takeaway
School terms, work calendars and sudden changes in weather can ask us to dive headfirst into a new season—but as humans, our bodies are often a little slower to catch up.
To make the transition flow more easily, identify where you might need some extra support right now, fill any nutritional gaps, and prepare your body for the months ahead. Your winter self will thank you!