Claims that a single habit can keep people from getting sick often travel farther than the evidence behind them, but doctors say a combination of vaccination, adequate sleep, movement, nutrition and stress management offers the most reliable support for immune health.
A Prevention feature on habits of people who report getting sick infrequently recently resurfaced with attention to an older study about sexual activity and immunoglobulin A, or IgA, an antibody found in saliva and other body fluids. The small study of 112 college students found higher salivary IgA in participants who reported sex once or twice a week than in groups reporting no sex, infrequent sex or more frequent activity.
The finding does not prove that a particular frequency of sex prevents infection. The study was small, relied on self-reported behavior and measured an immune marker rather than rates of colds, flu or other disease. Many factors, including stress, sleep, relationship quality and general health, could help explain the results.
Public-health guidance instead emphasizes interventions supported by larger bodies of evidence. Recommended vaccinations train the immune system to recognize specific pathogens. Handwashing reduces the spread of many respiratory and gastrointestinal infections, and staying home when sick can protect others.
Sleep also matters. In one controlled viral-exposure study cited by Prevention, participants sleeping five to six hours a night were more likely to develop a cold than those sleeping more than seven hours. Chronic sleep loss can alter immune signaling, while consistent sleep supports recovery and the response to vaccines.
Regular moderate physical activity is associated with better cardiovascular and metabolic health and can support normal immune function. Adults are generally advised to work toward at least 150 minutes of moderate aerobic activity each week, with adjustments for health and ability. More exercise is not automatically better; intense training without recovery can leave a person fatigued.
A varied diet supplies protein, vitamins, minerals and fiber needed by immune cells. No food or supplement can guarantee protection from infection. High-dose supplements can cause harm or interact with medicine, so people concerned about a deficiency should ask about testing rather than assuming more is better.
Close relationships and consensual intimacy can support emotional well-being and reduce stress for some adults. Sexual activity also carries pregnancy and infection risks that depend on partners and practices, making consent, communication and appropriate protection central to health.
The practical conclusion is broader than any single headline: People cannot eliminate the chance of illness, but they can reduce risk by keeping vaccines current, sleeping consistently, eating a balanced diet, moving regularly, washing hands and seeking care when symptoms are serious.
Source: Prevention, updated July 20, 2022. The immune-marker study is described as preliminary and does not establish disease prevention.
