There is no single best food for every illness, but a handful of foods have genuine research behind them, and the right choice depends on what kind of sick you are. Chicken soup, for instance, has been studied since the late 1970s and shows measurable effects on nasal congestion and inflammation. Honey outperforms some over-the-counter cough medicines in children. And the old advice about staying hydrated turns out to matter more than almost any specific food you put on your plate. The answers get more interesting once you look at what the body actually needs during different types of infection.
Chicken Soup Earns Its Reputation
Chicken soup is the most-studied comfort food in the context of illness, and it performs better than you might expect from something your grandmother also recommended. A study at the University of Nebraska Medical Center tested a traditional chicken soup recipe for its ability to affect white blood cells called neutrophils, which drive much of the inflammation behind cold symptoms like congestion, sore throat, and mucus production. The soup significantly slowed neutrophil movement in a lab setting, suggesting a mild anti-inflammatory effect that could ease upper respiratory symptoms.1PubMed. Chicken soup inhibits neutrophil chemotaxis in vitro Both the chicken and the vegetables contributed to this effect individually, and commercial soups varied widely in how well they worked.
Beyond the anti-inflammatory angle, chicken soup helps clear congestion through a separate mechanism. An earlier study measured how fast mucus moves through the nose after drinking different fluids. Hot chicken soup increased nasal mucus velocity more than plain hot water, and the researchers concluded the soup appeared to have something beyond just steam and heat driving the effect, possibly working through aroma or taste receptors at the back of the nose.2PubMed. Effects of drinking hot water, cold water, and chicken soup on nasal mucus velocity and nasal airflow resistance Cold water, by contrast, actually slowed mucus velocity. So sipping something warm and savory when you’re congested has a real physiological basis, and chicken soup in particular seems to do more than just warm you up.
There is also a practical reason chicken soup works well during illness: it delivers fluid, sodium, and a modest amount of protein in a form that is easy to get down when you have no appetite. The broth replaces water and electrolytes lost through sweating and fever, the protein from the chicken provides amino acids the immune system needs, and the whole package goes down easier than a plate of solid food when your throat hurts and your stomach is uneasy.
Hydration Is the Priority, Not Food
If you can only manage one thing while sick, make it fluids. Fever raises your metabolic rate and increases water loss through the skin. Vomiting and diarrhea obviously drain fluid and electrolytes fast. Even a straightforward respiratory infection increases water loss through heavier breathing and mucus production. Dehydration makes you feel worse, slows recovery, and in serious cases can become dangerous on its own.
Water is fine for mild illness, but when you’re losing fluids through vomiting or diarrhea, plain water does not replace the sodium and potassium you’re losing. Oral rehydration solutions work because glucose helps the small intestine pull sodium and water back into the body through a specific absorption pathway.3PubMed Central. Oral rehydration therapy in the second decade of the twenty-first century You do not need a commercial product for this. Broth-based soups, diluted juice, or a homemade mix of water, salt, and a small amount of sugar all work on the same principle. The key is getting some sodium and a little sugar in with the water so your gut can absorb it efficiently.
Drinks to be cautious with include anything highly caffeinated or very sugary. Coffee in large amounts is mildly diuretic, and sugary sodas can worsen diarrhea by pulling water into the intestine rather than out of it. Sports drinks are a step up from soda but typically contain more sugar than ideal for someone with gastroenteritis. If you’re mostly dealing with a cold or flu rather than a stomach bug, the specifics matter less, and whatever warm fluid you’ll actually drink is the right answer.
Honey for Coughs, Ginger for Nausea
Two foods have surprisingly strong evidence for specific symptoms. Honey, given to children with upper respiratory infections, reduced cough frequency and improved sleep quality compared to no treatment. It performed as well as dextromethorphan, the active ingredient in many over-the-counter cough syrups, with no significant difference between the two.4Archives of Pediatrics & Adolescent Medicine. Effect of Honey, Dextromethorphan, and No Treatment on Nocturnal Cough and Sleep Quality for Coughing Children and Their Parents Dextromethorphan, meanwhile, was no better than doing nothing at all. Honey’s thick, viscous texture coats the throat, and it has mild antimicrobial properties. One important caveat: honey should never be given to children under one year old due to the risk of botulism.
Ginger has a long history as an anti-nausea remedy, and the mechanism is now reasonably well understood. Active compounds in ginger, particularly gingerols and shogaols, work by blocking serotonin receptors in the gut and inhibiting a signaling pathway involving substance P, both of which are involved in triggering the vomiting reflex.5PubMed Central. Medicinal Plants for Chemotherapy-Induced Nausea and Vomiting: A Systematic Review of Antiemetic, Chemosensitizing, and Immunomodulatory Mechanisms Most of the clinical research on ginger and nausea comes from chemotherapy and pregnancy contexts, but the mechanism is the same regardless of why you feel queasy. Ginger tea, ginger chews, or even flat ginger ale with real ginger extract can help settle the stomach when you’re dealing with a stomach bug or medication-related nausea.
Menthol, found in peppermint, works on a different receptor system and can help with the sensation of a stuffy nose. Menthol activates cold-sensing receptors, which creates the subjective feeling of being able to breathe more easily even when your nasal passages have not actually opened much.6PubMed Central. Reciprocal effects of capsaicin and menthol on thermosensation through regulated activities of TRPV1 and TRPM8 Peppermint tea serves double duty here: the warm liquid helps clear mucus, and the menthol provides a cooling, analgesic sensation in the throat and airways.
Vitamin C, Zinc, and Elderberry
Vitamin C is the most-debated supplement for colds, and the evidence is more nuanced than either fans or skeptics tend to present. A meta-analysis found that vitamin C reduced the severity of common cold symptoms by about 15%, with a stronger effect on severe symptoms specifically. But it did not significantly shorten the duration of mild symptoms.7PubMed Central. Vitamin C reduces the severity of common colds: a meta-analysis So vitamin C is not a cure, but it can take the edge off how bad you feel during the worst days. You do not need mega-doses; getting vitamin C from food during illness, through citrus fruits, bell peppers, strawberries, or kiwi, is sufficient for most people.
Zinc has a different mechanism. Zinc ions can bind to the same receptor sites on cells that rhinoviruses use to gain entry, physically blocking the virus from attaching and replicating.8PubMed Central. Efficacy of Zinc Against Common Cold Viruses: An Overview This is why zinc lozenges need to dissolve slowly in the mouth to be effective. They work locally, bathing the throat in zinc ions. Swallowing a zinc pill does not accomplish the same thing. The evidence on zinc lozenges is mixed across trials, partly because the formulation matters: some binding agents in lozenges can neutralize the zinc ions before they do anything useful.
Elderberry has shown antiviral properties in lab settings. Flavonoids from elderberry extract bind directly to influenza virions and block them from entering host cells.9PubMed. Elderberry flavonoids bind to and prevent H1N1 infection in vitro The catch with lab findings like these is that blocking a virus in a petri dish is far easier than doing so inside a living person. Some small clinical trials have shown elderberry syrup shortens flu duration by a day or two, but the evidence base is still thin. It’s a reasonable supplement to try during flu season, but not something to rely on as a primary treatment.
Why You Lose Your Appetite When Sick
Loss of appetite during illness feels like a bug, but it is almost certainly a feature. Sickness-related appetite loss shows up across species, from insects to mammals, suggesting it has been conserved through evolution because it serves a purpose. Research indicates this appetite suppression may trigger a cellular recycling process called autophagy, where cells break down damaged components and repurpose them, a process that ramps up immune function.10PubMed Central. Sickness-Associated Anorexia: Mother Nature’s Idea of Immunonutrition?
This does not mean you should refuse all food when sick. It means that if you genuinely cannot eat, your body may be doing something deliberate, and forcing down a full meal is not always helpful. The practical takeaway: listen to your appetite. Sip broth, nibble on crackers or toast if you can, and do not guilt yourself into eating a large meal when the thought of food makes you feel worse. Your body’s appetite signals during illness are not random, they are part of the immune response.
Does “Feed a Cold, Starve a Fever” Have Any Basis?
This folk advice turns out to be a crude approximation of something real, at least in animal research. A study published in Cell found that in mice with bacterial infections, fasting was protective while feeding glucose worsened outcomes. The opposite was true for viral infections like influenza, where glucose intake was protective and blocking glucose utilization was lethal.11PubMed Central. Opposing Effects of Fasting Metabolism on Tissue Tolerance in Bacterial and Viral Inflammation These effects were largely independent of how many bacteria or viruses were in the animals’ bodies. Instead, the difference came down to how cells in different organs managed metabolic stress during each type of inflammation.
A 2024 review of the evidence noted that these findings remain mostly derived from animal studies, and translating them to human dietary advice requires caution.12PubMed. “Feed a Cold, Starve a Fever?” A Review of Nutritional Strategies in the Setting of Bacterial Versus Viral Infections Nobody is suggesting you should fast during a bacterial infection, and the mouse models used severe sepsis, not the kind of mild bacterial infection most people experience. Still, the underlying biology is fascinating: the body’s metabolic needs genuinely differ depending on whether the threat is bacterial or viral, and the old folk saying may have accidentally captured a real pattern that people noticed over centuries without understanding why.
For practical purposes, most colds and flus are viral, and the evidence leans toward eating when you can during viral illness. If you have a fever from a bacterial infection and genuinely have no appetite, the mouse data at least suggests your body might know what it’s doing. But staying hydrated remains non-negotiable in either case.
What to Avoid When You Feel Awful
Some foods make symptoms actively worse. Fatty and greasy foods are the most common offenders. Research on people with sensitive stomachs shows that dietary fat increases feelings of fullness, bloating, and nausea, with long-chain fats being worse than medium-chain fats.13PubMed Central. Dietary fat intake and functional dyspepsia When your stomach is already unsettled from illness, adding a heavy, oily meal is a reliable way to feel worse. Stick with low-fat, bland foods when your gut is irritated.
Dairy gets a mixed reputation during illness. Many people avoid milk when they have a cold because they believe it increases mucus production, but this is largely a myth. The thickened sensation in the mouth after drinking milk is an emulsion effect, not actual increased mucus. However, dairy is worth avoiding for a different reason during stomach illness. Viral gastroenteritis can temporarily damage the lining of the small intestine, reducing its ability to digest lactose. This means milk and ice cream that you normally tolerate fine may cause cramping and diarrhea during and shortly after a stomach bug.14PubMed Central. Lactose intolerance and gastrointestinal cow’s milk allergy in infants and children – common misconceptions revisited This temporary lactose intolerance resolves as the gut heals, usually within a few weeks.
Alcohol and spicy food are also best set aside. Alcohol suppresses immune function and worsens dehydration. Spicy food can irritate an already raw throat and upset stomach, though if you have pure nasal congestion and can handle the heat, capsaicin does temporarily open the airways.
Your Body Needs Extra Energy to Fight Infection
Fever alone raises your metabolic rate, meaning your body burns more calories just maintaining a higher temperature.15PubMed. The metabolic cost of fever On top of that, the immune system is an energy-hungry operation. Your liver ramps up production of specialized proteins, immune cells multiply rapidly, and all of this requires amino acids pulled from either your diet or your own muscle tissue. This is why you can lose weight and feel weak after even a moderate illness lasting several days.
Protein becomes particularly important during recovery. Even small amounts of protein from eggs, yogurt, chicken, or legumes can provide the building blocks your immune system is demanding. You do not need to eat large portions. Frequent small meals or snacks with some protein are easier to tolerate than three full meals, especially when your appetite is suppressed and your stomach is sensitive.
Fermented Foods During and After Illness
Yogurt, kefir, kimchi, sauerkraut, and other fermented foods contain live microorganisms that can interact with and influence the gut microbiome in both the short and long term.16PubMed Central. Fermented Foods, Health and the Gut Microbiome This matters during illness for two reasons. First, if you have taken antibiotics, they do not just kill the bacteria making you sick. They also disrupt the microbial community in your gut, which can cause diarrhea and digestive discomfort. Fermented foods can help repopulate the gut with beneficial organisms. Second, even without antibiotics, illness and reduced food intake shift the gut microbiome’s composition, and reintroducing fermented foods during recovery may help restore balance faster.
Plain yogurt in particular is a useful food during illness because it is soft, cold (soothing on a sore throat), provides protein and some calories, and delivers live cultures. Avoid yogurts loaded with added sugar, which can worsen diarrhea and feed less-desirable gut bacteria. If dairy bothers you during a stomach illness, as discussed above, non-dairy fermented options like kombucha, water kefir, or miso broth are alternatives that skip the lactose issue entirely.
A Practical Sick-Day Eating Guide
Pulling the evidence together, your eating strategy when sick depends on what symptoms you’re dealing with.
- Cold or flu with congestion: Hot chicken soup, hot tea with honey, citrus fruits, and zinc lozenges dissolved slowly in the mouth. Warm fluids help clear mucus, honey soothes coughs, and vitamin C may reduce symptom severity.
- Stomach bug with vomiting or diarrhea: Fluids with a little salt and sugar first, then bland foods like plain rice, toast, bananas, and applesauce as tolerated. Avoid dairy, fatty food, and heavy meals until your gut settles. Ginger tea or ginger chews for nausea.
- Fever and body aches: Stay hydrated above all. Small amounts of protein-containing food when your appetite allows. Do not force large meals. Broth-based soups are ideal because they cover hydration, electrolytes, and some nutrition in one package.
- Sore throat: Cold or room-temperature soft foods like yogurt, smoothies, and applesauce. Warm broth. Honey in tea. Avoid acidic foods like tomato soup or orange juice if they sting.
The common thread across all of these is that the “best” food when you’re sick is whatever provides fluids, a few key nutrients, and does not make your specific symptoms worse. Elaborate meals are unnecessary. Simple, familiar foods your body can process without a fight are the goal, and letting your appetite guide portion size is backed by real biology rather than laziness.