Part 4: The Body that Defends

Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

• Introduce peanut and well-cooked egg early, and keep them in the diet

  Under the 2017 US guidance, babies with severe eczema, egg allergy or both start peanut-containing food "as early as 4 to 6 months of age," after a clinician has considered...

  Topic 18

• Take antibiotics when needed, not just in case

  About 30% of US outpatient antibiotic prescriptions are likely inappropriate. Never refuse or stop a prescribed antibiotic without a clinician's advice (Chapter 20).

  Topic 18

• Keep washing your hands, with plain soap

  Handwashing prevents diarrheal illness. In 2016 the US Food and Drug Administration barred triclosan and 18 other antibacterial ingredients from consumer washes.

  Topic 18

• Skip raw milk, worms and immune-training supplements

  In the study that linked farm milk to less asthma, boiled farm milk showed no such link. Raw milk can carry Listeria, E.

  Topic 18

• For long exposure, use shade, clothing and a hat, then sunscreen

  When the UV index is 3 or above, Cancer Council Australia advises SPF 50 or 50+, broad-spectrum and water resistant, as "the last line of defence." Use it to prevent burning, not...

  Topic 19

• Wash as often as suits you, and wash your hands always

  Plain soap is enough. With eczema, seal each bath with moisturizer straight away: in a small trial in children, twice-daily baths sealed this way beat twice-weekly ones (●●○).

  Topic 19

• Treat the person, not the thermometer

  Use paracetamol (acetaminophen) or ibuprofen when fever makes you or your child miserable, not to hit a number. For children, give one drug at a time, not both together.

  Topic 20

• Know the red flags, and call a clinician when in doubt

  Get prompt medical help for a baby under 3 months with 38°C (100.4°F) or more, or 3 to 6 months with 39°C (102.2°F) or more.

  Topic 20

• Vaccinate on schedule

  Follow your national schedule for children and adults; if you are pregnant or have a weakened immune system, ask about live vaccines.

  Topic 20

• When your back first hurts, keep going

  Stay as active as pain allows. Bed rest slowed recovery, and most acute back pain settles within weeks, with or without paracetamol (acetaminophen).

  Topic 21

• Skip the routine scan

  Without warning signs, imaging does not improve outcomes, and "abnormal" findings are common in pain-free people of every age.

  Topic 21

• Move as treatment

  Choose exercise you will keep doing. In people recently recovered from back pain, a walking and education program that built up over three months to at least 30 minutes, five...

  Topic 21

• Retrain the alarm

  Learning how pain works does little for pain on its own. Structured treatment does more: eight weekly two-hour group sessions of CBT or mindfulness, or pain reprocessing therapy,...

  Topic 21

• Use medicines safely

  The World Health Organization advises against opioids as routine care for chronic primary low back pain.

  Topic 21

• Don't smoke; quit at any age

  Smoking causes about one US cancer in five and more than a quarter of cancer deaths.

  Topic 22

• Drink less

  "It is best not to drink alcohol," says the American Cancer Society. For those who do: "no more than 1 drink per day for women or 2 drinks per day for men."

  Topic 22

• Limit adult weight gain

  Stay in a healthy range and avoid gaining through adult life. Skip crash diets, get clinical support if you have an eating disorder, and treat weight-loss drugs as a decision for...

  Topic 22

• Breastfeed if you can and want to

  Each 12 months of breastfeeding, over a lifetime, lowers the relative risk of breast cancer by about 4.3%.

  Topic 22

• Vaccinate against HPV

  Swedish girls vaccinated against HPV (human papillomavirus) before 17 had 88% less invasive cervical cancer.

  Topic 22

• Screen on time

  In the US, colorectal screening starts at 45 and mammography every two years from 40 to 74; elsewhere, follow your national program.

  Topic 22

• Hormone medicines

  Weigh contraception and menopausal hormone therapy with a clinician; never stop a prescribed medicine without advice.

  Topic 22

Good observational evidence with a plausible mechanism, or small or few trials.

• Let young children live with animals and play outdoors

  A dog or farm animals in the first year are linked to less asthma at school age. A small Finnish pilot, not randomized, laid forest floor in daycare yards.

  Topic 18

• Get short, regular, unburnt sun

  When the UV index is 3 or above, a few minutes outdoors on most days keeps most people's vitamin D adequate; when it falls below 3, as in a southern Australian winter, spend time...

  Topic 19

• Never burn, and protect children and teenagers most

  Topic 19

• Skip sunbeds

  First use before 35 is associated with 87% higher melanoma risk.

  Topic 19

• Take vitamin D when the sun cannot supply it

  Britain's National Health Service (NHS) suggests 10 micrograms (400 IU) a day in autumn and winter, all year with dark skin or little time outdoors, and no more than 100...

  Topic 19

• Test with a reason

  The Endocrine Society found no trial evidence for routine screening, even for people with dark skin, and suggests against it.

  Topic 19

• Rest, drink and stay home while feverish

  Rest and fluids are standard self-care, and staying home protects others. No trial shows that rest shortens a fever.

  Topic 20

• Skip fever reducers "just in case" at vaccination

  They blunt the antibody response. Treat a distressed child afterwards as for any fever.

  Topic 20

• Use antibiotics well

  Do not ask for them for colds or flu, and never take leftover or borrowed pills.

  Topic 20

• Protect sleep

  One sleepless night lowered pain thresholds in 25 healthy adults, and in people with both insomnia and chronic pain, CBT for insomnia improves sleep substantially and pain...

  Topic 21

• Move

  Aim for 150 to 300 minutes of moderate activity a week, or 75 to 150 of vigorous. The most active adults had lower risk of 13 cancers.

  Topic 22

• Heed warning signs at any age

  Rectal bleeding, iron deficiency anemia or abdominal pain deserve a doctor's visit. Three in four colorectal cancers under 50 are found late.

  Topic 22

Early, small, animal-only, or actively contested.

• Keep people close

  Laughing with friends released opioids in the brains of 12 men, and holding a husband's hand damped the brain's threat response in 16 women (Chapter 42).

  Topic 21

• Night-shift workers: no proven protective step

  Don't count on melatonin; in one test of 31 supplements, contents ranged from 83% below to 478% above the label.

  Topic 22