Spring Supplements: Separating Evidence from Hype
- , by SANUSq Research team
- 13 min reading time
Every spring, the shelves fill up with cleanses, "reset" kits and seasonal bundles promising to wash away the winter. The reality behind spring supplements is quieter, and more useful: most people don't need a basketful of products when the clocks go forward, but one or two nutrients do make genuine sense at the end of winter. Here is how to tell the evidence from the hype.
Why spring sells so many supplements
After months of short days, little sunshine and often a narrower diet, plenty of people reach March feeling flat. That feeling is real. But it doesn't automatically mean you are deficient in something, and it certainly doesn't mean your body needs "cleaning out".
Spring marketing leans on a simple story: winter has left you sluggish and clogged up, and a product will restore you. The more useful question is narrower. What does winter actually deplete, and what can you sensibly do about it?
The cleanse question: what "detox" claims leave out
Let's deal with the biggest spring promise first. Products sold as a "detox" or cleanse rarely say which toxins they remove, how they remove them, or how anyone measured the result.
Your body already has a clearance system that works around the clock: the liver processes a wide range of compounds and the kidneys filter the blood and excrete waste. There is no evidence that this system "fills up" over winter or needs a seasonal flush.
In a critical review of the evidence, Klein and Kiat (2015) found very little clinical evidence to support the use of commercial detox diets. The few human studies were hampered by flawed methods and small sample sizes, and the authors were not aware of any randomised controlled trials testing commercial detox diets in people.
The habits that often come bundled with a cleanse, such as drinking more water, eating more vegetables and cutting back on alcohol, are good ideas at any time of year. The benefit comes from those habits, not from the product.
Vitamin D: top of the spring supplements list
If there is one nutrient with a genuinely seasonal logic, it is vitamin D. Most of our vitamin D is made in the skin when it is exposed to ultraviolet B (UVB) light from the sun. Across much of Europe, the winter sun is too low in the sky for the skin to make meaningful amounts for several months of the year. Stores gradually run down, and blood levels tend to reach their lowest point in late winter and early spring.
O'Neill et al. (2016) modelled vitamin D-effective UVB across European locations from 35° N to 69° N. All locations showed significant seasonal variation, and the "vitamin D winter", when the sun is too weak for useful skin production, ranged from none in the far south to eight months in the far north. In populations with higher vitamin D intakes, the seasonal dip in blood levels was much smaller.
In the Dutch Lifelines cohort, Verbakel et al. (2025) measured vitamin D status in 1,000 adults in March 2023. Although status had improved since 2011, up to a quarter of people in some groups, including 26% of men aged 70 and over, were deficient at the end of winter. Status was highest in the groups already advised to supplement.
Vitamin D contributes to the normal function of the immune system and to the maintenance of normal bones and muscle function. After a long winter, many people's status is simply lower than it was in the autumn.
Some groups are more likely to run low:
- Older adults, whose skin makes vitamin D less efficiently.
- People with darker skin, who need more sun exposure to make the same amount.
- Anyone who spends little time outdoors or keeps most of their skin covered.
- People living further north, where the vitamin D winter is longest.
Food helps only a little: oily fish, egg yolks and fortified foods are the main sources, so diet alone rarely covers winter needs. Vitamin D3 is the form most often used in supplements, and it is frequently paired with vitamin K2, which contributes to normal blood clotting and to the maintenance of normal bones.
More is not better. Vitamin D is stored in the body, and very high intakes over time can cause harm, so stay within the amount on the label unless your doctor advises otherwise. If you take a blood thinner such as warfarin, speak to your doctor before starting any product containing vitamin K. And if you are unsure of your status, a simple blood test for 25-hydroxyvitamin D is far better guidance than guesswork.
Magnesium and end-of-winter tiredness
The second credible candidate is magnesium. Many people eat a little less of it than recommended, often because their diet is low in whole grains, pulses, nuts and leafy greens.
In a review of national survey data, Rosanoff et al. (2012) reported that almost half (48%) of the US population consumed less than the required amount of magnesium from food in 2005–2006. The authors also cautioned that standard intake requirements may be harder to pin down than often assumed.
The authorised wording here is precise: magnesium contributes to the reduction of tiredness and fatigue, to normal energy-yielding metabolism and to normal muscle function. That is a real role, but not a burst of energy in a bottle. It is most relevant if your diet is genuinely short of magnesium-rich foods.
There is no simple, reliable routine test for magnesium status, so start with your plate. If it is light on plants and whole foods, adjust your diet first; a supplement can come second, at a sensible dose. If tiredness is persistent or unexplained, see your doctor.
Vitamin C and the spring larder
Vitamin C has a good reputation for a reason: it contributes to the normal function of the immune system and to the reduction of tiredness and fatigue. Spring is also the season when markets fill with fresh produce that contains plenty of it.
In a review of vitamin C and immunity, Carr and Maggini (2017) described how vitamin C supports several functions of the immune system and noted that deficiency results in impaired immunity. They suggested that intakes providing adequate to saturating blood levels, around 100–200 mg a day, are a reasonable baseline, an amount many people can reach from fruit and vegetables.
For most people, a varied, colourful diet covers what they need. A supplement may make sense if you eat few fruits and vegetables or smoke. Vitamin C is water-soluble and the body excretes what it can't use, so there is no point chasing very large amounts.
For those who prefer a measured daily amount, SANUSq also offers Liposomal Magnesium and Liposomal Vitamin C + Glutathione. Choose according to an actual need, not on principle.
Hay fever season: what the research shows
For many people, spring means pollen. Hay fever (allergic rhinitis) is a medical condition, and it is worth getting proper advice: a pharmacist can recommend suitable over-the-counter options, and your doctor can help if symptoms are severe, persistent or affect your breathing.
A systematic review and meta-analysis by Kawada et al. (2025) pooled five randomised trials of vitamin D supplementation in people with allergic rhinitis. Overall, the difference in symptoms compared with placebo was not statistically significant, and the results varied widely between studies. A subgroup analysis suggested an effect in people not using corticosteroids, but the small number of trials means the finding is preliminary.
In other words, this is an open research question, not a reason to take vitamin D for hay fever. Supplements are not a substitute for the care a pharmacist or doctor can offer.
And this year's other seasonal favourites?
Each spring brings its own stars: spirulina, herbal cleanse teas, adaptogens such as ashwagandha. Some have genuine interest in specific contexts; others rest mostly on reputation. What most share is that the solid human evidence is thinner than the marketing suggests.
That doesn't make them worthless, but they don't deserve the priority slot. When a spring programme promises to fix everything at once, healthy scepticism is the right response.
Before the capsules: sunlight, food, movement and sleep
No supplement replaces the fundamentals, and spring is when they become easiest to enjoy:
- Get back outside. Short, sensible spells of sun on bare skin restart your own vitamin D production. Avoid burning.
- Eat what's in season. Young leaves, radishes, asparagus, strawberries and fresh herbs bring colour, fibre and micronutrients to your plate.
- Move more. Lighter evenings make regular walking, cycling or gardening easier to fit in.
- Reset your sleep. Morning light helps anchor the body clock as the days lengthen.
How to choose spring vitamins sensibly
The golden rule is to target, not to stack:
- Start with the likeliest gap. For most people in Europe at the end of winter, that is vitamin D.
- Test rather than guess if you are unsure. A blood test arranged by your doctor settles the question.
- Stick to the label dose and check the totals if you take more than one product.
- Ask first if you take regular medication, have a health condition, or are pregnant or breastfeeding.
A good supplement is the right nutrient, at the right dose, for the right reason.
Frequently asked questions
What is the most useful supplement in spring?
For most people in Europe, vitamin D. Levels are often at their lowest at the end of winter because there is too little UVB sunlight for the skin to make it. Vitamin D contributes to the normal function of the immune system and to the maintenance of normal bones.
Do I need to cleanse my body after winter?
No. Your liver and kidneys clear waste from the body continuously, and there is very little clinical evidence that commercial cleanse products add anything. Fresh food, enough water and regular activity are a far better use of your effort and money.
Does magnesium help with tiredness?
Magnesium contributes to the reduction of tiredness and fatigue and to normal energy-yielding metabolism. It is most relevant if your diet is low in magnesium-rich foods. If tiredness persists, see your doctor to rule out other causes.
Should I take vitamin D all year round?
It depends on your vitamin D status, how much time you spend outdoors and where you live. Many official recommendations focus on autumn and winter. Talk to your doctor, ideally with a blood test result to hand.
How do I know if my vitamin D is low?
The most reliable way is a blood test for 25-hydroxyvitamin D, arranged by your doctor. It is especially worth considering at the end of winter or if you rarely get sun on your skin, and it saves you supplementing blind.
Can I take several supplements at once?
It's better to target what you actually need than to stack products. If you take regular medication, or are unsure, ask your pharmacist or doctor before combining supplements.
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References
- Klein AV, Kiat H. Detox diets for toxin elimination and weight management: a critical review of the evidence. Journal of Human Nutrition and Dietetics. 2015;28(6):675–686. PMID 25522674
- O'Neill CM, Kazantzidis A, Ryan MJ, et al. Seasonal changes in vitamin D-effective UVB availability in Europe and associations with population serum 25-hydroxyvitamin D. Nutrients. 2016;8(9):533. PMID 27589793
- Verbakel MR, Verkaik-Kloosterman J, Dinnissen CS, Koopman N, Ocké MC, de Jong MH. Vitamin D status of adults in the North of the Netherlands: cross-sectional results from the Lifelines cohort study. European Journal of Clinical Nutrition. 2025;79(11):1114–1120. PMID 40999062
- Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated? Nutrition Reviews. 2012;70(3):153–164. PMID 22364157
- Carr AC, Maggini S. Vitamin C and immune function. Nutrients. 2017;9(11):1211. PMID 29099763
- Kawada K, Sato C, Ishida T, et al. Vitamin D supplementation and allergic rhinitis: a systematic review and meta-analysis. Medicina (Kaunas). 2025;61(2):355. PMID 40005471
Read more on the blog
- Why Your Vitamin D Might Not Be Working →
- How Does the Immune System Work? →
- Top Causes of Unexplained Fatigue →
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The team at SANUSq.
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The health information in this article is provided for educational purposes only. Consult your healthcare professional before making any medical decisions.
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