Explore each chapter to understand the effort, benefits and context.
This chapter covers things that look inexpensive and effective, but whose benefits turn out to be negligible, nonexistent, or sometimes negative when you read the original research. The order reflects how much people spend on them and how strong the evidence is. Start by dropping the items near the top. Prices in this chapter refer to China and are in RMB.
Around 14,000 male doctors took multivitamins for eleven years. Serious cardiovascular events and deaths were no less common than among those taking a placebo. Combining nine trials involving over 50,000 people also showed no association with mortality. Skipping the supplements saves RMB 200–700 a year. This does not apply to diagnosed deficiencies or folic acid during pregnancy.
Two large trials enrolled roughly 26,000 people and 15,000 people with diabetes. Taking 1 gram of fish oil daily did not produce a clear reduction in serious cardiovascular events or deaths. Evidence that eating fish is beneficial does not automatically establish that fish-oil capsules are beneficial. Skipping them saves RMB 400–1,000 a year.
Supplementing for five years did not clearly reduce cancer, cardiovascular disease, or deaths in trials that did not specifically recruit vitamin-D-deficient people. Confirmed deficiency, osteoporosis, and prolonged lack of sunlight are different situations; follow medical advice.
These supplements can do more than fail to help. Across 78 trials involving almost 300,000 people, some analyses found slightly higher mortality. Two large trials in smokers or people exposed to asbestos found 18%–28% more lung cancer and 8%–17% higher mortality with the tested beta-carotene regimens. Smokers and people exposed to asbestos should be especially cautious.
After 24 weeks, six out of ten people taking a placebo reported less knee pain. Glucosamine or chondroitin improved on that by only around four or five percentage points, differences small enough to be explained by chance. Spending RMB 700–1,800 a year did not establish a benefit beyond the substantial improvement also seen with a placebo.
Taking vitamin C every day does little to prevent colds in the general population. Starting it after a cold begins has inconsistent effects. Regular use can shorten an adult cold by about 8%, roughly half a day; decide whether that is worth several hundred RMB a year. Marathon runners and soldiers exercising in cold environments are exceptions: their cold incidence was approximately halved.
More testing does not automatically mean fewer cancer deaths. Screening people without symptoms can find abnormalities that are harmless, while setting off expensive and sometimes harmful investigations. Use screening tests with demonstrated benefit for your age and risk.
A tracker does not supply the behavior change for you. In one two-year trial, people given a wearable lost less weight than people receiving the same lifestyle program without one.
There is no strong evidence that organic food is more nutritious. Only three studies in the cited review directly examined health outcomes after people ate it, and none found a difference. Organic produce was 30 percentage points less likely to have detectable pesticide residues, but detecting a residue does not mean a safety limit was exceeded. Eating more fruit and vegetables can be beneficial whether or not they are organic.
Chinese health-food labels must state that the product is not a medicine and cannot replace medicines for treating disease. The first six entries examine familiar ingredients such as multivitamins, fish oil, and vitamin D and do not establish the broad wellness benefits used to market them. Many of these purchases are gifts for parents or hosts. The intention to show care is valuable, but it does not give an expensive tonic a medical benefit.
A review of 45 trials in healthy adults found no lasting change to the gut microbiome from routine probiotics: changes generally faded after supplementation stopped, and blood lipids did not improve. Specific uses, such as preventing antibiotic-associated diarrhea, have a separate evidence base and are outside this entry.
In a trial of 3,018 people, cold showers reduced sickness absence by 29%, but did not reduce days of illness; that does not establish that people became ill less often. A 2025 review of 11 trials found temporarily increased inflammatory markers after cold exposure and no clear change in immune measures. Enjoyment is a different reason to take cold showers from treating them as a proven health investment; the notes address safety limits.
The detox industry is large, but supporting clinical evidence is sparse, and the cited review found no rigorous trials of commercially sold detox diets. A separate review of dietary acid or alkali, alkaline water, and cancer found only one eligible study, which did not demonstrate an association.
A review tracing the origin of “eight glasses a day” found no scientific study supporting that exact rule. Food and other drinks already supply a substantial amount of water. For most people, thirst and urine color are useful guides. Working in heat, vigorous exercise, a history of kidney stones, and reduced thirst in older age call for more deliberate attention to drinking.
In a classic classroom experiment, students received supposedly personalized personality descriptions that were actually identical, yet generally considered them accurate. That helps explain why readings can feel so convincing. Losses can also go far beyond a small entertainment fee: a fortune-telling fraud ring in Xixian, Henan, charged for incense offerings and “support packages” costing up to RMB 3,888, and its ringleader received an eleven-year prison sentence.
Blue-light-filtering lenses have not shown a meaningful advantage over ordinary lenses for eye strain or visual clarity, and there is no evidence here that they protect the macula. Screen-related soreness and dryness can improve; working at a screen for a few months does not automatically ruin your eyes. Welding arcs, ultraviolet light, lasers, and an acute glaucoma attack are different hazards that can cause serious injury.
Claims that donation detoxifies the body, lowers blood lipids, or prevents heart attacks are not supported by randomized trials. People able to keep donating are healthier to begin with. Accounting for that reduced an apparent mortality benefit per extra annual donation from nearly 20% to 7.5%. A randomized trial of iron reduction found no clear mortality difference. Frequent donation can, however, cause iron deficiency, fatigue, and feeling cold.
People offered generic health checks did not have lower overall, cardiovascular, or cancer mortality in the reviewed trials. Focus on the particular screenings with supporting evidence. In China, the national basic public-health program provides an annual free blood-pressure measurement from age 35 and an annual free health examination from age 65.
For high uric acid without a previous gout attack or tophi, the American College of Rheumatology conditionally recommends against starting urate-lowering medicine. Treating 24 people for three years would prevent one gout flare. Trials of using allopurinol to protect kidneys also found no slowing of kidney-function decline. An actual gout diagnosis changes the decision.
Most people with symptom-free gallbladder stones remain symptom-free over the periods studied. In Italy, 78% of 580 people had no symptoms over nearly nine years. In a US group of 135 people followed for about four years, only 7% underwent surgery. UK guidance says that incidentally discovered stones in an otherwise normal gallbladder and biliary tree do not need treatment unless symptoms develop.
People with calcium-oxalate stones are often told to eat less calcium, but a trial found the opposite dietary approach worked better. Men with recurrent stones who ate normal amounts of calcium while reducing animal protein and salt had about half as many recurrences over five years as those on a low-calcium diet. UK guidance also advises against restricting dietary calcium.
Claims that an object changes your fortune, attracts wealth, or improves health lack verifiable support. Like fortune-telling, vague promises invite you to fit your own experience to them. Medical claims can amount to false advertising; Chinese regulators took action against a livestream seller for such claims in 2026. Buying something because you like it as jewelry is a separate choice.
People who place greater importance on money and possessions tend to report lower well-being, but the association is weak and its direction is unclear. Other research suggests that buying experiences can bring more happiness than buying objects. An outing or a meal with someone may therefore be more useful than a full shopping cart when you feel low.
Among people with similar incomes, those with richer neighbors reported lower well-being. The association was concentrated among neighbors with similar educational backgrounds and more social contact. Paying extra to move somewhere everyone is wealthier can leave you feeling further behind. However, when both personal and neighborhood incomes rise together, well-being still improves: absolute living standards matter too.
A popular theory says exerting self-control on one task leaves less for the next, so willpower must be rationed. A coordinated replication across 23 laboratories and 2,141 participants found an effect close to zero. Avoid treating “I used up today’s willpower” as an established explanation, or paying for courses built around stockpiling it.
The claim that skipping breakfast inevitably causes overeating later was not supported by the trials: breakfast skippers ate over 200 fewer kilocalories daily and weighed slightly less. Over a year, adding time-restricted eating to calorie restriction did not clearly improve weight loss. Habitual breakfast skipping is associated with about 17% more cardiovascular disease, but the cited long-term study did not establish a difference in overall mortality.