Immune Boosters: Expert Reveals What Really Helps.
Do ginger shots really help? Is vitamin C the secret weapon against colds? And how effective is hot lemon water? Our experts reveals what really helps to support the immune system.
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As temperatures drop and the cold and flu season sets in, tips for boosting the immune system take centre stage. Many sound convincing; some have persisted for years and are recommended time and again. But what does the science say? Which measures can actually support our immune system and which are more myth than miracle cure?
Nutritionist Maria Loos has examined the most popular immune-boosting tips and explains which ones really make a difference.
Overrated or underrated? Immune boosters examined
Tip 1: Hot lemon water
Maria’s assessment: Lemon slices in your tea—does that really boost the immune system? While lemons do provide vitamin C, the amounts are significantly lower than many people assume; lemon slices in tea are usually insufficient to provide a meaningful intake. Furthermore, some of the vitamin C is destroyed by very hot water, which further limits the health benefits.
Conclusion: Tea with lemon is a pleasant home remedy that is soothing as a warm drink, especially during cold season. However, one should not expect it to significantly strengthen the immune system or provide reliable protection against infections.
Tip 2: Ginger-Shots
Maria’s assessment: Ginger shots typically contain concentrated ginger, lemon juice, and often other ingredients such as turmeric or apple. Ginger provides bioactive compounds like gingerols and shogaols, which are credited with anti-inflammatory and antioxidant properties. Studies also show that ginger offers some benefit for nausea.1
However, research into ginger shots is still in its early stages. The studies conducted so far are mostly small-scale, and there is currently no evidence that they prevent colds or measurably boost the immune system. Furthermore, many ready-made products can contain large amounts of added sugar.
The bottom line: Ginger can be beneficial, but as an immune booster, the ginger shot is somewhat overrated.
Tip 3: High Dose of Vitamin C
Maria’s assessment: Vitamin C supports the function of various immune cells. But does more necessarily mean better? The assumption that very high doses can prevent colds is not supported by the scientific evidence. Major reviews2 show that, in healthy people, regular Vitamin C intake generally does not reduce the number of colds.
Moreover, excess vitamin C is largely excreted. What is often overlooked is that there are a number of other micronutrients that support immune system function—such as iron, vitamins A, D, B6, and B12, folic acid, copper, selenium, and zinc. Therefore, broad-spectrum supplements containing all immune-relevant micronutrients are the better choice.
Conclusion: High-dose does not necessarily mean better. A holistic nutritional supplement can make an important contribution to greater well-being and a strong immune system.
Tip 4: 7h+ Sleep
Maria’s assessment: The immune system is by no means “switched off” during sleep—quite the opposite. Immune defence processes are coordinated and regenerated overnight. Sleep deprivation can impair the function of key immune cells, such as natural killer cells and T cells, and measurably alter inflammatory markers.
In a prospective study, the risk of actually falling ill after exposure to cold viruses was significantly higher in individuals who slept less than seven hours per night.3 Experimental studies also show that even a single night of sleep deprivation can alter the immune response.4,5
Conclusion: Regular 7-9 hours of sleep is one of the most effective and best-proven measures for a strong immune system. Anyone who consistently doesn't sleep enough increases their susceptibility to infections and measurably weakens their immune function.
Tip 5: Immune-Superfoods
Maria’s assessment: Citrus fruits, acai, goji berries, and other so-called superfoods are often considered natural immune boosters. In fact, many of these foods provide valuable vitamins, trace elements, and phytochemicals that can contribute to a balanced diet. However, there is no scientific evidence that specific foods can specifically strengthen the immune system or protect against colds.
Rather, one's overall diet is crucial for a well-functioning immune system. A varied diet rich in vegetables, fruit, whole grains, high-quality protein sources, and healthy fats provides the body with all essential nutrients in the long term. Individual foods cannot replace this overall effect.
Conclusion: Superfoods are healthy components of a balanced diet - but a single food does not make the immune system stronger. Variety on the plate always beats individual superfoods. Anyone who regularly eats colorful, fresh and, if possible, unprocessed foods creates the best basis for a functioning immune system.
Eating for Immune Health in Autumn & Winter
Brassicas: kale, Brussels sprouts, white cabbage, red cabbage, Savoy cabbage, and pointed cabbage – rich in vitamin C, fibre, and phytochemicals.
Root and tuber vegetables: carrots, beetroot, parsnips, parsley root, celeriac, and swedes - provide vitamins, minerals, and satiating fibre.
Other winter vegetables: broccoli, leeks, lamb's lettuce, chicory, and pumpkin - provide additional vitamins and variety on the plate.
Seasonal fruit: Apples and pears, as well as citrus fruits such as oranges, mandarins, and grapefruits, supplement the vitamin supply.
Legumes: Lentils, beans, and chickpeas provide high-quality plant-based protein, fibre, as well as iron and zinc.
Whole grain products: Rolled oats, whole grain bread, whole grain pasta, and brown rice provide the body with fibre and important B vitamins.
Nuts and seeds: Walnuts, hazelnuts, and almonds, as well as pumpkin, sunflower, and flax seeds, provide healthy fats, vitamin E, and trace elements.
Protein-rich foods: Fish (e.g., herring, mackerel, or salmon), eggs, dairy products, or tofu contribute to the supply of high-quality protein.
Fermented foods: Plain yogurt, kefir, and sauerkraut can support a diverse gut flora.
Tip 6: Movement
Maria’s assessment: Regular physical activity is one of the best-supported measures for a healthy immune system. Moderate exercise can improve the circulation of immune cells, favourably influence inflammatory processes, and support the body's defence against respiratory infections.6,7 What is particularly interesting is that consistency matters more than intensity. Very intense exertion without adequate recovery can place a short-term strain on the immune system. For most people, therefore, the key is not pushing to the limit, but rather finding a balance between regular, moderate exercise, recovery, and sleep. Highly recommended is 30 minutes of physical activity (such as brisk walking, cycling, swimming, or jogging) 3–5 times a week.
Conclusion: Moderate physical activity is one of the most effective measures for a healthy immune system.
Conclusion: The most impactful factors
The immune system cannot be optimised with a single immune booster or superfood. Rather, scientific evidence shows that a strong immune system results from the interplay of many factors.
The most impactful factors are:
sufficient sleep
regular exercise
a varied, micronutrient-rich diet
Everything else can be a useful supplement, but it does not replace these fundamentals.
- 1)
Anh NH, Kim SJ, Long NP, Min JE, Yoon YC, Lee EG, Kim M, Kim TJ, Yang YY, Son EY, Yoon SJ, Diem NC, Kim HM, Kwon SW. Ginger on Human Health: A Comprehensive Systematic Review of 109 Randomized Controlled Trials. Nutrients. 2020 Jan 6;12(1):157.
2)Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews 2013, Issue 1. Art. No.: CD000980.
3)Aric A. Prather, Denise Janicki-Deverts, Martica H. Hall, Sheldon Cohen, Behaviorally Assessed Sleep and Susceptibility to the Common Cold, Sleep, Volume 38, Issue 9, September 2015, Pages 1353–1359
4,5)Spiegel K, Sheridan JF, Van Cauter E. Effect of Sleep Deprivation on Response to Immunizaton. JAMA. 2002;288(12):1471–1472.
Spiegel K, Rey AE, Cheylus A, Ayling K, Benedict C, Lange T, Prather AA, Taylor DJ, Irwin MR, Van Cauter E. A meta-analysis of the associations between insufficient sleep duration and antibody response to vaccination. Curr Biol. 2023 Mar 13;33(5):998-1005.e2.
6,7)David C. Nieman, Laurel M. Wentz, The compelling link between physical activity and the body's defense system, Journal of Sport and Health Science, Volume 8, Issue 3, 2019, Pages 201-217
Campbell JP and Turner JE (2018) Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan. Front. Immunol. 9:648.