Cold Soup: What the Clinical Evidence Says

Is it possible to “treat yourself with soup” without self-deception? The authors of a new systematic review in Nutrients collected all available clinical studies on soups as a nutritional intervention for acute respiratory infections in adults - and found a cautious but consistent signal of benefit. On average, regular consumption of soup during ARI is associated with a milder course of symptoms and a slightly shorter illness (by 1-2.5 days), and in two studies - also with a decrease in inflammatory markers (IL-6, TNF-α, CRP). This is not a “miracle pill”, but an affordable addition to conventional therapy that works due to hydration, warmth, nutritional value and, possibly, anti-inflammatory components.

Background

Acute respiratory infections (ARI) are one of the most common reasons for absence from work and seeking medical care in adults. Most patients are prescribed only supportive therapy: rest, fluids, antipyretics as indicated. Against this background, the "cultural recommendation" of warm soup for a cold has long been alive. It is loved for its availability and safety, but clinicians are traditionally skeptical about it: does a "bowl of soup" help with anything other than comfort and placebo?

There are several plausible mechanisms why soup may provide measurable benefits. Warm liquid moistens mucous membranes and thins secretions, facilitating mucociliary clearance; the volume of fluid and salt helps with hydration during fever; protein and amino acids support the metabolic needs of the immune response during periods of poor appetite; vegetables and greens provide polyphenols and trace elements; spices (garlic, ginger, pepper) have mild anti-inflammatory and vasodilatory effects, and the steam above the cup improves subjective nasal breathing. Soup also has high “compliance”: unlike complex diets, it is easy to eat precisely when it is difficult to eat.

Yet the evidence base has long been fragmented. Dietary interventions are difficult to blind, recipes and dosages vary widely, and controls often use water or no intervention, which poorly separates specific effects (soup composition) from non-specific ones (heat, fluid volume, ritual). The few RCTs have had small samples and heterogeneous outcomes: some measure symptom dynamics, others inflammatory markers, and almost none “hard” measures like abstinence and return visits.

This raises a practical request: to collect available clinical studies in one systematic review, to assess whether there is a reproducible effect of soup on the course of ARI in adults, what is its approximate size and what outcomes it affects (symptoms, duration of illness, inflammatory markers). The task is to separate “grandmother’s advice” from the romance of the kitchen and to understand whether it is possible to formally recommend soup as a cheap and safe adjuvant to standard cold care.

What exactly did they do and what did they find?

• This is the first systematic review of the effectiveness of soup for ARI in adults: PRISMA selection, protocol registered in PROSPERO (February 2024), search in MEDLINE/Scopus/CINAHL/Cochrane and registries. Four studies (n = 342) were included, design - RCTs and controlled before-after.
• Interventions were most often chicken soups with vegetables and herbs; compared with water, "other" soup, or no intervention.
• Conclusion: Moderate reduction in symptom severity and shortening of duration by 1-2.5 days; 2 of 4 studies showed reduction in inflammatory biomarkers. Data on absence from work/school and well-being were lacking.
• The authors assess the certainty of the evidence as low-moderate: the samples are small, the methods are heterogeneous, and formal GRADE has not been performed. Large RCTs with consistent outcomes are needed.

Why would soup help at all? There is no magic here. Warm liquid moisturizes mucous membranes and thins secretions, calories and protein support the immune system in the midst of a fever, vegetables and greens provide polyphenols and minerals, spices like garlic and ginger add a mild anti-inflammatory effect. Plus, banal compliance: soup is a culturally understandable food that is easy to eat even if you have a poor appetite.

Details to look out for

• What soups were studied: most often chicken soups with vegetable broth, sometimes with herbs; in some studies, the recipe was adapted to the region (for example, “vegetable-chicken” in Vietnam).
• Comparisons: water/warm drink, "alternative" soup, no intervention - this is important for a fair assessment of non-specific effects (heat, volume of liquid).
• What wasn’t measured (and in vain): not a single study tracked absintheism and quality of life - key indicators for practice.
• Who benefits most: As the authors emphasize, soup is a cheap and culturally familiar supplement, which is important in resource-limited settings and for outpatient care.

Yes, the evidence base is still thin, but the idea of "food as medicine" here seems especially down-to-earth: nothing exotic, minimal risks, and a clear biological meaning. The soup does not replace antiviral/symptomatic agents, but it adds hydration, calories, and gentle anti-inflammatory support - and this is exactly what an adult with an ARI needs.

What does this mean in practice?

• When appropriate: Cold/flu-like symptoms in adults without signs of severe disease, as an adjuvant to standard care (sleep, fluids, antipyretics as indicated).
• What to put in the pan:
  • Broth + water (volume!),
  • Vegetables (onions, carrots, celery, greens),
  • Protein source (chicken/turkey/legumes),
  • Spices (garlic, ginger, pepper) - as tolerated.
  The logic is maximum liquid and nutrition with a light texture.
• What not to expect: soup does not reduce the disease "in half" and does not cancel the doctor if there is a high temperature >3 days, shortness of breath, severe weakness, chest pain and other alarming signs. (This review did not study, but this is a basic clinic.)

Viewing Limitations

There are only four studies, the designs and formulations are different, it was not possible to create a meta-analysis - only a narrative synthesis. Hence the caution in the wording and the call for large RCTs with uniform symptom scales, biomarkers, taking into account absinthism and quality of life. And another nuance: dietary interventions are difficult to blind, so it is important to select active controls (for example, warm drinks) - the authors note this separately.

What will science test next?

• Standardize the “recipe” and dosage: portions/frequency, protein density, proportion of vegetables and spices.
• Add "hard" outcomes: absinthism, repeat visits, adverse effects.
• Mechanisms: association of ingredients with IL-6/TNF-α/CRP changes, role of hydration and temperature.
• Economics: A simple assessment of the costs and benefits for clinics and employers.

Conclusion

Soup is not a panacea, but it is a reasonable and affordable addition to a cold: it helps to endure the symptoms a little easier, get back on your feet a little faster - and is almost risk-free. The remaining "homework" is large, careful RCTs to turn grandma's advice into formal recommendations.

Source: Lucas S., Leach MJ, Kimble R., Cheyne J. Were Our Grandmothers Right? Soup as Medicine-A Systematic Review of Preliminary Evidence for Managing Acute Respiratory Tract Infections. Nutrients, July 7, 2025; 17(13):2247. https://doi.org/10.3390/nu17132247