Screening tests by age

Screening means testing people without symptoms. It's valuable when catching a disease early actually changes the outcome — which is not true of every disease, and is why "more testing" is not automatically better. Tests that find harmless abnormalities lead to biopsies, anxiety, and treatment of things that would never have caused harm. The recommendations below reflect where the benefit clearly exceeds that cost.

Blood pressure

High blood pressure has no symptoms until it causes a stroke, heart attack, kidney failure, or heart failure. Roughly half of U.S. adults have it and a large share of them either don't know or aren't controlled. It's the highest-yield thing on this page for most people, and treatment is cheap.

Measuring it correctly matters more than people expect. Sit with your back supported and feet flat on the floor, arm resting at heart level, no talking, after five minutes of quiet, and at least 30 minutes after caffeine, exercise, or smoking. Cuff size matters — a cuff that's too small reads high, which is a common source of unnecessary diagnosis. Home monitoring over a week gives a far better picture than one clinic reading.

What lowers it: reducing sodium (most dietary sodium comes from packaged and restaurant food, not the salt shaker), the DASH dietary pattern, regular aerobic exercise, weight loss if applicable, limiting alcohol, and treating sleep apnea. When those aren't enough, generic medications are inexpensive and well tolerated. Needing medication is not a personal failure — blood pressure has a large genetic component.

Physical activity

The evidence here is unusually consistent across large cohort studies: regular physical activity reduces all-cause mortality, cardiovascular disease, type 2 diabetes, several cancers, dementia risk, depression, and falls in older adults. Few interventions touch that many outcomes.

The most important finding for most people is that the curve is steepest at the beginning. Going from sedentary to roughly 20 minutes of walking a day captures a large share of the total available mortality benefit. Going from very active to extremely active adds comparatively little. If the 150-minute target feels out of reach, that's not a reason to do nothing — it's the wrong number to be looking at.

Strength training is the most commonly skipped half. Muscle mass and strength decline with age and predict independence, fall risk, and mortality. Two sessions a week is enough to matter, and bodyweight work counts.

Prolonged sitting carries risk somewhat independent of exercise, though the effect is attenuated in people who meet activity guidelines. Breaking up long sitting periods is a reasonable, low-cost addition.

Diet

Nutrition science is genuinely harder than most fields — people can't be randomized to eat one way for thirty years, self-reported intake is unreliable, and confounding is severe. So the honest summary is that a handful of patterns are well supported and most specific claims about individual foods are not.

What holds up

• Dietary patterns beat individual nutrients. Mediterranean and DASH-style eating — vegetables, fruits, legumes, whole grains, nuts, fish, olive oil, limited red and processed meat — are associated with lower cardiovascular risk, and in the case of the Mediterranean pattern, supported by randomized trial evidence.
• Fiber is under-consumed and consistently beneficial. Higher intake tracks with lower cardiovascular disease, type 2 diabetes, and colorectal cancer risk. Most adults get well under the recommended 25–35 g per day.
• Sodium. Most people consume far more than the ~2,300 mg daily upper limit, and the great majority of it is already in food before it reaches the table.
• Added sugar, especially in liquid form. Sugar-sweetened beverages are the most consistently implicated single item, likely because liquid calories don't produce compensating fullness.
• Processed meat is a group 1 carcinogen for colorectal cancer. The relative risk is modest and the absolute risk increase is small — this is a reason to eat less of it, not to panic about a sandwich.
• Trans fats are the one clear case of a food ingredient with no safe level, now largely removed from the food supply.

What doesn't hold up as well as claimed

• Dietary cholesterol turned out to matter much less than believed for most people; saturated fat intake and overall pattern matter more.
• Most "superfood" claims come from short-term studies of surrogate markers — antioxidant levels, inflammatory markers — rather than health outcomes people care about.
• Detoxes and cleanses have no mechanism. Your liver and kidneys already do this continuously and are not improved by juice.
• Specific meal timing (including most intermittent fasting protocols) shows benefits that largely track with the reduced total calorie intake it tends to produce, rather than the timing itself.

Sleep

Most adults need 7 to 9 hours. Chronic short sleep is associated with cardiovascular disease, hypertension, impaired glucose regulation, weakened immune response, depression, and a sharply elevated accident risk. The subjective sense of having adapted to less sleep is not supported by objective performance testing — people underestimate their own impairment.

Children need substantially more: roughly 10–13 hours for preschoolers, 9–12 for school-age children, and 8–10 for teenagers. Adolescent circadian rhythms genuinely shift later at puberty, which is why early school start times have been repeatedly associated with worse outcomes.

For persistent insomnia, cognitive behavioral therapy for insomnia (CBT-I) is the first-line treatment and outperforms sleep medication over the long term, without dependence or next-day impairment. It's underused mostly because it's less familiar than a prescription, not because it works less well. Several evidence-based digital programs exist.

Screen for sleep apnea if you snore loudly, have witnessed pauses in breathing, or wake unrefreshed despite adequate time in bed. It's common, frequently undiagnosed, and a treatable driver of hypertension and cardiovascular risk.

Tobacco & nicotine

Smoking remains the largest single preventable cause of death in the U.S. The mortality gap between smokers and never-smokers is on the order of a decade of life expectancy.

Quitting works at every age, and the benefit is larger than most people assume. Quitting before 40 avoids nearly all of the excess mortality risk from continued smoking. Even quitting after 60 adds years. Cardiovascular risk begins dropping within months.

What actually helps you quit: the combination of medication plus behavioral support roughly doubles to triples success rates over willpower alone. Varenicline is the most effective single medication; combination nicotine replacement (a patch for baseline plus a short-acting form for cravings) works better than a patch alone. Most people need several attempts — a relapse is data about what to adjust, not evidence that quitting is impossible.

On e-cigarettes, honestly: for an adult who already smokes and has failed other methods, switching completely is very likely less harmful than continuing to smoke, and some randomized evidence supports them as a cessation aid. That is a genuinely different question from whether adolescents should use them, where the answer is clearly no — nicotine affects the developing brain, and youth vaping frequently establishes a dependence that didn't exist before. Both things are true; conflating them has muddied public messaging in both directions.

Alcohol

The evidence here has shifted meaningfully, and it's worth being direct about it. The long-standing claim that moderate drinking protects the heart has largely not survived better study designs. Much of the apparent benefit came from comparing drinkers against an abstainer group that included people who had quit because they were sick. Studies using genetic variants that affect alcohol metabolism — a design far less vulnerable to that confounding — generally find no cardiovascular benefit.

Meanwhile, alcohol is classified as a group 1 carcinogen, with established causal links to cancers of the breast, colon, rectum, liver, esophagus, mouth, throat, and larynx. For breast cancer in particular, risk rises from low levels of consumption, with no clear threshold below which it's absent.

The practical summary: less is better, and none is a reasonable choice. Where upper limits are given they are typically no more than 2 standard drinks a day for men and 1 for women — and these are ceilings not to exceed, not targets to reach. There is no amount established as beneficial. Pregnancy and alcohol don't mix at any amount.

If cutting down is difficult, that's a common and treatable problem. Naltrexone and acamprosate are effective medications for alcohol use disorder and are dramatically underprescribed.

Mental health

Mental health conditions are medical conditions, with measurable biology, effective treatments, and outcomes that improve with care. Depression is among the leading causes of disability worldwide.

What the evidence supports: psychotherapy — particularly CBT and related structured approaches — is effective for depression and anxiety, with effect sizes comparable to medication for mild-to-moderate cases. Medication is effective, more clearly so as severity increases. Combining both generally outperforms either alone for moderate-to-severe depression. Exercise has a real, replicated antidepressant effect, useful as an adjunct though not a replacement for treatment in severe illness.

Practical notes that often go unsaid: antidepressants take 4–6 weeks for full effect, and the first medication tried doesn't work for everyone — that's expected, not failure. Don't stop abruptly; discontinuation symptoms are real and tapering is straightforward when planned.

Supplements

In the U.S., dietary supplements are not reviewed for safety or effectiveness before sale. Independent testing has repeatedly found products that contain less, more, or something other than what the label states. This is a structural regulatory gap, not a fringe concern.

Where supplementation has good support:

• Folic acid — 400 mcg daily for anyone who could become pregnant. Prevents neural tube defects, and must be taken before pregnancy is recognized to work.
• Vitamin D for people with documented deficiency, limited sun exposure, or certain conditions. Routine high-dose supplementation in healthy adults has repeatedly failed to reduce fractures, cancer, or cardiovascular events in large trials.
• Vitamin B12 for people on vegan diets, older adults with reduced absorption, and those on long-term metformin or acid-suppressing medication.
• Iron for diagnosed iron-deficiency anemia — diagnosed, because unnecessary iron is harmful.
• Vitamin K at birth for newborns, which prevents a rare but catastrophic bleeding disorder.

Where it mostly doesn't: multivitamins have not been shown to reduce mortality, cardiovascular disease, or cancer in generally well-nourished adults. Antioxidant supplements have in some trials increased risk — beta-carotene raised lung cancer incidence among smokers, which is a useful reminder that "natural" and "safe" are unrelated. High-dose vitamin C does not prevent colds.

Tell your clinician what you take. Supplements interact with medications — St. John's wort reduces the effectiveness of many drugs including hormonal contraception, and several supplements affect bleeding risk around surgery.

Injury and overdose

For people under 45, injury — not disease — is the leading cause of death. It gets a fraction of the attention, and much of it is preventable.

• Seat belts, correct car seats, helmets. Unglamorous and enormously effective. Car seat installation is done incorrectly a majority of the time; free inspection is widely available.
• Firearm storage. Storing firearms locked, unloaded, and separate from ammunition is associated with lower rates of unintentional injury and youth suicide. This is a safety measure, independent of any position on firearm policy.
• Naloxone. Reverses opioid overdose, is available over the counter in the U.S., is safe to give if you're wrong about what's happening, and works on fentanyl. Worth having if anyone in your household uses opioids — prescribed or not.
• Falls in older adults. A leading cause of injury death over 65. Strength and balance training, a medication review for drugs that cause dizziness, vision checks, and removing home trip hazards all reduce risk measurably.
• Carbon monoxide and smoke alarms. Test them; replace batteries annually.
• Drowning is a leading cause of death in young children and is usually silent and fast. Layered protection — fencing, swim lessons, and constant undistracted supervision — works better than any single measure.

Last reviewed: August 2026. Screening recommendations summarize U.S. Preventive Services Task Force guidance and relevant specialty society recommendations. Recommendations differ somewhat between organizations — particularly for breast and prostate cancer screening — and those differences reflect real judgment calls about weighing benefit against overdiagnosis rather than disagreement about the underlying data. See Evidence & Sources.