regulates · weak evidence

regulates · 51

This page lists the 51 with weak evidence. The 119 with strong evidence → 136 with moderate evidence →

Acne Zincweak · 2 cited
Some people with acne have low blood zinc, and bringing it back into the normal range is what zinc is for in acne; the evidence behind it is limited. Getting back to normal is enough, and taking very large amounts long term does harm.
After birth and breastfeeding Ironweak · 3 cited
Milk iron does not change with the mother's intake, so the iron question after birth is the mother's own: blood lost at delivery drains her stores, while in the first 8 weeks of exclusive breastfeeding periods rarely return, saving the iron that bleeding would take. Where anemia in pregnancy is common, the World Health Organization says iron may be given for 6 to 12 weeks after birth, a recommendation based on low-certainty evidence.
After birth and breastfeeding Depression & Anxietyweak · 2 cited
Progesterone and estrogen fall sharply after birth. In an experiment with only 16 women that simulated high pregnancy hormone levels and then withdrew them, 5 of the 8 women with a history of postnatal depression developed clear depressive symptoms and none of the other 8 did, suggesting that some people are unusually sensitive to hormone withdrawal. The World Health Organization recommends screening for depression and anxiety after birth with a validated questionnaire.
After birth and breastfeeding Training on short sleepweak · 2 cited
In the first months after birth, total sleep each night averages about 7.2 hours, which sounds like plenty, but it is interrupted again and again: the hard part is broken sleep, not short sleep. These months are not the time to force hard training; short, easy activity that you can stop at any moment fits best, and a low mood that has not passed after two weeks may be postnatal depression and calls for a doctor.
Asian Ginseng Type 2 Diabetesweak · 2 cited
Blood glucose is one of the few areas where ginseng has moderate-quality human evidence, but "moderate" and "small" belong together: pooled randomized trials show fasting glucose does fall a little, to a statistically significant degree, while HbA1c, fasting insulin and insulin resistance do not improve. Because it really does lower glucose a little, adding it on top of diabetes medication carries a risk of low blood sugar.
Autonomic Nervous System · HRV Heartweak · 1 cited
In population statistics, chronically low heart rate variability (HRV) goes along with a cluster of cardiovascular risk factors. That is the autonomic-imbalance hypothesis: low HRV may be the shadow of a vagal brake that has been off its post for a long time. But this is a statistical association, the direction may run the other way, and how strong it is has long been debated, so your HRV today cannot tell you whether you have heart disease.
Biotin Hair Lossweak · 2 cited
Biotin is a cofactor for several carboxylase enzymes, and true deficiency does cause hair loss. In people who are not deficient, extra biotin does not grow hair; it can instead interfere with lab tests and make results such as thyroid function or cardiac troponin falsely high or low.
Caffeine + L-Theanine Palpitationsweak · 2 cited
The link between coffee and palpitations is weaker than people assume. In one randomized trial, coffee days brought no clear rise in atrial premature beats, about half again as many ventricular ones, and 36 fewer minutes of sleep; another study of 1388 older adults found habitual coffee and tea unrelated to premature beats. If you suspect coffee, test it by alternating days rather than cutting it out wholesale.
Calf & Lower Leg Sedentary office bodyweak · 2 cited
One cost of long sitting is that muscles stop contracting for hours and stop taking fat and glucose out of the blood. The soleus is the fatigue-resistant slow muscle of the calf; in a short lab study in sedentary people, driving it with a seated, repeated heel raise made the rise in blood sugar and insulin after a meal smaller. This is a mechanistic signal, not a proven daily therapy, and it is no substitute for real exercise.
Celiac disease Mouth ulcersweak · 2 cited
Coeliac disease is a gluten-triggered immune disease of the gut that often impairs absorption of iron, folate and B12, all of which are linked to mouth ulcers. Pooling 22 observational studies, people with coeliac disease have about 2.45 times the usual risk of recurrent mouth ulcers. This is an association, not proof; and the mouth signs of coeliac disease can appear years before gut symptoms, so recurring ulcers are worth asking a doctor about testing for it even without diarrhea.
Curcumin Heartweak · 2 cited
Curcumin looks like it treats almost everything in the test tube, largely because it interferes with the assays themselves, and very little of it reaches the blood when taken by mouth. A medicinal chemistry review notes that no double-blind, placebo-controlled trial has shown it works. It cannot carry an anti-inflammatory plan for the heart.
DIM / I3C Endocrineweak · 2 cited
DIM affects how the liver processes estrogen that has already been used: it shifts the mix of estrogen breakdown products toward the milder 2-hydroxyestrone. In a 12-month trial in women taking tamoxifen, that ratio did rise, but breast density did not change; and the active metabolites of tamoxifen were lower in the DIM group, and whether that weakens the drug is not known.
Eating in later life Vitamin Dweak · 2 cited
The skin's raw material for vitamin D declines with age: in skin samples removed during surgery, skin from people in their late 70s and early 80s made less than half as much vitamin D precursor under the same ultraviolet light as skin from children and young people. Older people also go out less and show less skin, so they run short more easily.
GERD Chronic coughweak · 2 cited
Refluxed stomach contents (not only acid but also gas and non-acid fluid) may irritate vagal nerve endings in the throat and airway and turn the cough reflex up, and an esophagus that moves poorly is common in chronic cough. But this route is often overrated: in a multicenter survey in China, reflux-related cough made up only 4.6%, and without acid reflux, acid-suppressing drugs do no better than placebo.
Growing taller Youth & adolescent trainingweak · 2 cited
Children grow taller at the growth plates near the ends of the bones, the same still-growing cartilage that youth training has to respect. In controlled strength-training trials in children, growth in height was not affected; the claim that lifting stunts growth is not supported by the trials so far.
Immune Aging & Inflammaging Vitamin Dweak · 2 cited
Keep two things apart: filling a gap back to normal is worthwhile, mainly for bone, though the latest pooling of trials no longer shows that vitamin D prevents respiratory infections; topping up someone who already has enough adds nothing. Immunity is not better the higher it goes; a supplement can bring you back to normal, not push you beyond it.
Insomnia Ashwagandhaweak · 2 cited
The third thread of insomnia is the stress axis (HPA): cortisol that stays high makes it hard to fall asleep and keeps sleep light. Ashwagandha is sold to calm exactly this axis, but it is only an aid. A problem in any of the three threads, sleep pressure, the body clock or the stress axis, can cause insomnia, so first work out which one it is.
Interference effect Health and performanceweak · 2 cited
Long endurance training and heavy strength training send muscle down two different molecular paths, one building more mitochondria and the other more contractile protein. When you try to push performance up in both at once, a large amount of endurance work slows strength and muscle gains somewhat, more with running than with cycling; the drag matters mainly to people chasing their limits.
Iron-Deficiency Anemia Palpitationsweak · 2 cited
Iron-deficiency anaemia is one of the body-wide causes of palpitations: with fewer oxygen-carrying red cells, the heart beats faster to make up. If palpitations come with tiredness or heavy periods, a blood count gets to the answer more directly than trying a supplement.
Lion's Mane Nervousweak · 3 cited
Lion's mane has a respectable mechanistic starting point: in a dish, several of its small molecules make cells produce more nerve growth factor (NGF), which prompts neurons to grow new branches. The chain breaks between the dish and the brain: NGF itself cannot cross the blood-brain barrier, and there is no human evidence on how much of these small molecules reaches the brain after you swallow them, or whether they boost NGF signaling there.
Lutein + Zeaxanthin Eyes · Myopia · Screensweak · 2 cited
Lutein and zeaxanthin concentrate in the macula, the center of the retina, and the people with trial evidence for an eye-health formula are those who already have intermediate macular degeneration. Myopia means the eyeball has grown too long, and no supplement can shorten it, so protecting the macula and preventing myopia are separate problems.
Microplastics IBSweak · 2 cited
This pathway gets mentioned a lot, but the evidence is still early: in cell and animal studies, plastic particles may reduce the tight-junction proteins between gut lining cells, loosening the gut barrier, and shift the makeup of gut bacteria. Its link to irritable bowel syndrome is so far only an association, not established cause and effect.
Milk Thistle Glutathioneweak · 2 cited
In cell and animal studies, silybin partly restores depleted glutathione; but after it is swallowed, very little reaches the blood, and most of what does is in conjugated form, so whether this step can happen in a person is an open question.
Nasal Breathing & Mouth Taping Respiratoryweak · 2 cited
The paranasal sinuses continuously produce a little nitric oxide (NO), which travels down into the lungs with each breath in and slightly widens only the small vessels beside the alveoli that have just received fresh air, so air and blood flow are matched more closely. In the small experiments of Lundberg 1996, healthy people had higher blood oxygen tension breathing through the nose than through the mouth, and arterial oxygen rose in intubated patients when air from their own noses was fed back in; how much this contributes in everyday breathing is still unsettled, and mouth breathing bypasses this nitric oxide altogether.
Palpitations Strokeweak · 2 cited
One kind of palpitation is atrial fibrillation, a beat that is irregular with no pattern, and it raises the risk of stroke. In a smartwatch study of 419,000 people, 34% of those who got an irregular-pulse alert and later wore an ECG patch had atrial fibrillation. So a watch alert is worth an ECG, and a newly irregular heartbeat with no pattern that you feel yourself means seeing a doctor the same day.
Picky eating Ironweak · 2 cited
Picky eaters eat little meat, so iron and zinc are easy to run short of: in the UK ALSPAC cohort, persistently picky children ate about 40% less carcass meat and had lower iron and zinc intakes. Toddlers grow fast and need plenty of iron, and after age 1 cow's milk should stay under 500 mL a day. Only a blood test shows whether a child is short of iron; whether to supplement is for a pediatrician to decide.
Power and jumping Knee Painweak · 3 cited
Pain between the kneecap and the shin is often linked to repeated running and jumping, and is commonly called jumper's knee. In a cohort of young volleyball players, the more hours they trained, the higher their risk of jumper's knee, an observed association; stiff landings raise the impact, and teaching people to bend the hips and knees together and land on the front of the foot clearly lowers it.
Power and jumping Youth & adolescent trainingweak · 1 cited
Children can do jump training too. A systematic review of 7 studies found that children aged 5 to 14 clearly improved their running and jumping after jump training, and that it was safe when parents consented, the children agreed to take part and safety rules were built in; the studies, though, were all of low quality.
Pregnancy + exercise Training on short sleepweak · 2 cited
In the months after birth when you get up at night to feed, sleep is broken into pieces, and exercise then helps more than the body alone. The American College of Obstetricians and Gynecologists writes that physical activity can be an important factor in preventing postpartum depression, and in a meta-analysis of 12 controlled trials, exercise during pregnancy and after birth lowered postpartum depressive symptoms, more so in mothers who already had them. Returning to training after birth follows the postnatal check and starts again from the lightest level.
Quercetin Hallmarks of Agingweak · 1 cited
Quercetin's most interesting modern direction is clearing senescent cells (as a senolytic): damaged cells that did not finish dying get stuck in a state where they neither divide nor die, and keep releasing inflammatory factors that add to chronic inflammation throughout the body. Dasatinib plus quercetin (D+Q) is one of the few such approaches to reach human trials, and a preliminary trial in people with diabetic kidney disease saw fewer senescent cells; it remains an experimental treatment.
Rhodiola rosea Burnout Syndromeweak · 1 cited
In one of the few randomized trials in burnout (Olsson 2009), 60 people with fatigue from long-term stress took a standardized extract for 4 weeks and improved more than placebo on a burnout scale and several attention measures, though both groups improved markedly on placebo and the trial was small and single-center. At most it is an add-on; it cannot replace changes to workload and recovery, which are what actually work.
Running form + shoes Running for beginnersweak · 2 cited
The evidence that changing your running form or shoes prevents injury is weak. For a beginner, injury prevention rests on building up volume gradually and adding strength training, which gives tendons and bone time to adapt; putting all your attention on shoes crowds out what matters more.
Sedentary office body Varicose veinsweak · 2 cited
Standing still, pressure in the foot veins can reach 80 to 90 mmHg, and sitting still leaves the calf muscle pump just as switched off; once you walk, the calf muscles squeeze blood upward and, with working valves, bring it below 30 mmHg. That is why long periods of standing or sitting are listed as a risk factor for varicose veins, and getting up to walk a few steps, or raising your feet when you sit, is the usual advice.
Sleep Architecture & Sleep Debt Growing tallerweak · 2 cited
Growth hormone's largest daily release follows deep sleep after falling asleep: in two small studies in young adults, delaying sleep delayed the peak, and reversing sleep and waking by 12 hours moved the peak with sleep. Growth hormone drives the growth plates, but the step from sleep to a child's final height has not been measured directly.
Starting from zero Sedentary office bodyweak · 2 cited
People who sit all day can slip movement into the sitting itself, not only into a short stretch after work. In a small randomized crossover trial, overweight adults who got up and walked for 2 minutes every 20 minutes of sitting had about a 24% smaller blood-sugar response after a meal, and the American College of Sports Medicine says that breaking up sitting with frequent short bouts of standing and activity brings health benefits, even for people who already exercise.
Starting from zero Neck Painweak · 1 cited
A neck and shoulders stiff from long sitting will not be fixed by a few more steps. For chronic mechanical neck pain, strength training for the neck, shoulder blades and upper limbs, combined with stretching, brings a moderate reduction in pain that holds at longer follow-up, and these exercises need no gym equipment.
Starting from zero DOMS sorenessweak · 3 cited
When you are just starting or try a new movement, muscles that get sore a day or two later and recover within a few days are normal delayed-onset muscle soreness. A few cases are not: unaccustomed exercise done too hard all at once can trigger rhabdomyolysis, and pain and swelling far out of proportion to the training, weak muscles or dark urine mean going to the emergency department immediately.
Starting from zero Training injuriesweak · 2 cited
When you add load from zero, no percentage holds for everyone: in a randomized trial of 532 novice runners, a plan built on adding no more than 10% a week did not reduce injuries. What survives is the principle of adjusting to your habitual activity and your response to exercise and raising intensity and volume gradually, which the American College of Sports Medicine says may reduce the risks of exercise.
Starting solids Picky eatingweak · 3 cited
The tastes and textures a baby practices when starting solids carry on into the toddler years. After 10 tries of the same vegetable, babies were all eating more of it; in an English cohort, children first given lumpy food after 9 months ate less fruit and vegetables at 7 and had more feeding problems, an observational finding. A review likewise lists lumpy foods introduced late and pressure to eat among the causes of picky eating.
Taurine · anti-aging?Hallmarks of Agingweak · 3 cited
A 2023 study found that blood taurine falls with age in mice, monkeys and humans, and restoring it in middle-aged mice extended median lifespan by about 10–12%. But working in mice is not the same as working in people: the human data are only correlations, and a 2025 study of 137 men found no link between taurine levels and age.
Tongkat Ali Testosterone & Agingweak · 3 cited
Tongkat ali is thought to affect testosterone in two ways: by boosting testosterone production in the testes and inhibiting its conversion to estrogen, and by lowering cortisol a little. These mechanisms come mostly from cell and animal studies. In people, a meta-analysis of 5 randomized trials reported higher total testosterone, most firmly in men whose testosterone was low; the often-quoted Tambi 2012 study had no control group.
Training injuries Warm-up & cool-downweak · 2 cited
The part of a warm-up worth doing is raising body temperature and rehearsing the movements, which makes the session better. What actually prevents injury is something else: in a meta-analysis of randomized trials, strength training cut sports injuries by about two thirds, while stretching showed no effect. You also have to keep the pace of increasing your training in check.
Training on short sleep Starting from zeroweak · 2 cited
The talk test and perceived effort read how the body is responding right now, not a fixed pace or weight, so on short sleep they scale the intensity down on their own. In one experiment, 11 men ran for 30 minutes at their own pace after 30 hours awake; their perceived effort was about the same as after normal sleep, yet they covered less distance. If you can still talk in full sentences fairly comfortably, you are below the ventilatory threshold.
Training on short sleep Training injuriesweak · 2 cited
On short sleep, reaction and skill decline first, which makes mistakes in contact and complex movements more likely; that is the reason to drop contact, technical work and heavy sets close to failure first on a short-sleep day. In a retrospective study of 112 adolescent athletes, those who slept less than 8 hours a night on average were 1.7 times as likely to have had an injury; that is an observed association and cannot show that short sleep caused it.
Vestibular System Vitamin Dweak · 3 cited
A Korean multicenter randomized trial (Jeong 2020) gave vitamin D and calcium only to people with BPPV whose repositioning had worked and whose blood vitamin D was low (25(OH)D below 20 ng/mL, that is, 50 nmol/L), and recurrence over a year fell from 46.7% to 37.8%. The trial did not test whether people who are not short of vitamin D benefit; repositioning is still the treatment itself, and the result does not carry over to falls or fractures.
Vitamin A Respiratoryweak · 2 cited
Vitamins C and E and the carotenoids together form the lung's antioxidant network, but the benefit from the diet as a whole is modest. A single nutrient at a high dose backfired: in the ATBC trial, beta-carotene supplements raised lung cancer in smokers by 18%.
Vitamin B6 Menstrual Cycleweak · 2 cited
Vitamin B6 has some evidence for easing premenstrual symptoms, but it is limited. It is also one of the few water-soluble vitamins that harms when overdone: taking more than 100 mg a day long term can cause peripheral neuropathy, meaning numbness and tingling in the hands and feet. Keep both the benefit and the risk in mind.
Vitamin C Cold, Flu & Allergyweak · 1 cited
Vitamin C against colds is a widely repeated claim, but in the trials pooled by a Cochrane systematic review, long-term supplements did not reduce colds in the general population; regular supplements shortened colds in adults by only about 8%, and starting once symptoms appear did essentially nothing.
Vitamin E Heartweak · 2 cited
After vitamin E stops a free radical in a cell membrane, it becomes a tocopheroxyl radical itself and needs vitamin C to restore it. Large trials of vitamin E supplements found no cardiovascular benefit; one explanation from test-tube work is that high-dose vitamin E on its own lets these radicals build up, but that has not been measured directly in people.
Water & Electrolytes Migraineweak · 2 cited
Dehydration may trigger migraine in some people, but migraine itself is a neurovascular disorder in which a signaling molecule called CGRP is a key link, and a newer class of drugs for preventing and treating attacks is designed to target it. Relying on drinking more water alone misses the treatments that actually work.
Zinc Cold, Flu & Allergyweak · 1 cited
Zinc lozenges may shorten a cold by about two days, but a Cochrane systematic review rated the certainty of that evidence as low, with results varying widely between studies, and side effects such as nausea and a bad taste in the mouth are common; for preventing colds, zinc does almost nothing.

regulates · 51

Acne Zincweak · 2 cited

Some people with acne have low blood zinc, and bringing it back into the normal range is what zinc is for in acne; the evidence behind it is limited. Getting back to normal is enough, and taking very large amounts long term does harm.

After birth and breastfeeding Ironweak · 3 cited

Milk iron does not change with the mother's intake, so the iron question after birth is the mother's own: blood lost at delivery drains her stores, while in the first 8 weeks of exclusive breastfeeding periods rarely return, saving the iron that bleeding would take. Where anemia in pregnancy is common, the World Health Organization says iron may be given for 6 to 12 weeks after birth, a recommendation based on low-certainty evidence.

After birth and breastfeeding Depression & Anxietyweak · 2 cited

Progesterone and estrogen fall sharply after birth. In an experiment with only 16 women that simulated high pregnancy hormone levels and then withdrew them, 5 of the 8 women with a history of postnatal depression developed clear depressive symptoms and none of the other 8 did, suggesting that some people are unusually sensitive to hormone withdrawal. The World Health Organization recommends screening for depression and anxiety after birth with a validated questionnaire.

After birth and breastfeeding Training on short sleepweak · 2 cited

In the first months after birth, total sleep each night averages about 7.2 hours, which sounds like plenty, but it is interrupted again and again: the hard part is broken sleep, not short sleep. These months are not the time to force hard training; short, easy activity that you can stop at any moment fits best, and a low mood that has not passed after two weeks may be postnatal depression and calls for a doctor.

Asian Ginseng Type 2 Diabetesweak · 2 cited

Blood glucose is one of the few areas where ginseng has moderate-quality human evidence, but "moderate" and "small" belong together: pooled randomized trials show fasting glucose does fall a little, to a statistically significant degree, while HbA1c, fasting insulin and insulin resistance do not improve. Because it really does lower glucose a little, adding it on top of diabetes medication carries a risk of low blood sugar.

Autonomic Nervous System · HRV Heartweak · 1 cited

In population statistics, chronically low heart rate variability (HRV) goes along with a cluster of cardiovascular risk factors. That is the autonomic-imbalance hypothesis: low HRV may be the shadow of a vagal brake that has been off its post for a long time. But this is a statistical association, the direction may run the other way, and how strong it is has long been debated, so your HRV today cannot tell you whether you have heart disease.

Biotin Hair Lossweak · 2 cited

Biotin is a cofactor for several carboxylase enzymes, and true deficiency does cause hair loss. In people who are not deficient, extra biotin does not grow hair; it can instead interfere with lab tests and make results such as thyroid function or cardiac troponin falsely high or low.

Caffeine + L-Theanine Palpitationsweak · 2 cited

The link between coffee and palpitations is weaker than people assume. In one randomized trial, coffee days brought no clear rise in atrial premature beats, about half again as many ventricular ones, and 36 fewer minutes of sleep; another study of 1388 older adults found habitual coffee and tea unrelated to premature beats. If you suspect coffee, test it by alternating days rather than cutting it out wholesale.

Calf & Lower Leg Sedentary office bodyweak · 2 cited

One cost of long sitting is that muscles stop contracting for hours and stop taking fat and glucose out of the blood. The soleus is the fatigue-resistant slow muscle of the calf; in a short lab study in sedentary people, driving it with a seated, repeated heel raise made the rise in blood sugar and insulin after a meal smaller. This is a mechanistic signal, not a proven daily therapy, and it is no substitute for real exercise.

Celiac disease Mouth ulcersweak · 2 cited

Coeliac disease is a gluten-triggered immune disease of the gut that often impairs absorption of iron, folate and B12, all of which are linked to mouth ulcers. Pooling 22 observational studies, people with coeliac disease have about 2.45 times the usual risk of recurrent mouth ulcers. This is an association, not proof; and the mouth signs of coeliac disease can appear years before gut symptoms, so recurring ulcers are worth asking a doctor about testing for it even without diarrhea.

Curcumin Heartweak · 2 cited

Curcumin looks like it treats almost everything in the test tube, largely because it interferes with the assays themselves, and very little of it reaches the blood when taken by mouth. A medicinal chemistry review notes that no double-blind, placebo-controlled trial has shown it works. It cannot carry an anti-inflammatory plan for the heart.

DIM / I3C Endocrineweak · 2 cited

DIM affects how the liver processes estrogen that has already been used: it shifts the mix of estrogen breakdown products toward the milder 2-hydroxyestrone. In a 12-month trial in women taking tamoxifen, that ratio did rise, but breast density did not change; and the active metabolites of tamoxifen were lower in the DIM group, and whether that weakens the drug is not known.

Eating in later life Vitamin Dweak · 2 cited

The skin's raw material for vitamin D declines with age: in skin samples removed during surgery, skin from people in their late 70s and early 80s made less than half as much vitamin D precursor under the same ultraviolet light as skin from children and young people. Older people also go out less and show less skin, so they run short more easily.

GERD Chronic coughweak · 2 cited

Refluxed stomach contents (not only acid but also gas and non-acid fluid) may irritate vagal nerve endings in the throat and airway and turn the cough reflex up, and an esophagus that moves poorly is common in chronic cough. But this route is often overrated: in a multicenter survey in China, reflux-related cough made up only 4.6%, and without acid reflux, acid-suppressing drugs do no better than placebo.

Growing taller Youth & adolescent trainingweak · 2 cited

Children grow taller at the growth plates near the ends of the bones, the same still-growing cartilage that youth training has to respect. In controlled strength-training trials in children, growth in height was not affected; the claim that lifting stunts growth is not supported by the trials so far.

Immune Aging & Inflammaging Vitamin Dweak · 2 cited

Keep two things apart: filling a gap back to normal is worthwhile, mainly for bone, though the latest pooling of trials no longer shows that vitamin D prevents respiratory infections; topping up someone who already has enough adds nothing. Immunity is not better the higher it goes; a supplement can bring you back to normal, not push you beyond it.

Insomnia Ashwagandhaweak · 2 cited

The third thread of insomnia is the stress axis (HPA): cortisol that stays high makes it hard to fall asleep and keeps sleep light. Ashwagandha is sold to calm exactly this axis, but it is only an aid. A problem in any of the three threads, sleep pressure, the body clock or the stress axis, can cause insomnia, so first work out which one it is.

Interference effect Health and performanceweak · 2 cited

Long endurance training and heavy strength training send muscle down two different molecular paths, one building more mitochondria and the other more contractile protein. When you try to push performance up in both at once, a large amount of endurance work slows strength and muscle gains somewhat, more with running than with cycling; the drag matters mainly to people chasing their limits.

Iron-Deficiency Anemia Palpitationsweak · 2 cited

Iron-deficiency anaemia is one of the body-wide causes of palpitations: with fewer oxygen-carrying red cells, the heart beats faster to make up. If palpitations come with tiredness or heavy periods, a blood count gets to the answer more directly than trying a supplement.

Lion's Mane Nervousweak · 3 cited

Lion's mane has a respectable mechanistic starting point: in a dish, several of its small molecules make cells produce more nerve growth factor (NGF), which prompts neurons to grow new branches. The chain breaks between the dish and the brain: NGF itself cannot cross the blood-brain barrier, and there is no human evidence on how much of these small molecules reaches the brain after you swallow them, or whether they boost NGF signaling there.

Lutein + Zeaxanthin Eyes · Myopia · Screensweak · 2 cited

Lutein and zeaxanthin concentrate in the macula, the center of the retina, and the people with trial evidence for an eye-health formula are those who already have intermediate macular degeneration. Myopia means the eyeball has grown too long, and no supplement can shorten it, so protecting the macula and preventing myopia are separate problems.

Microplastics IBSweak · 2 cited

This pathway gets mentioned a lot, but the evidence is still early: in cell and animal studies, plastic particles may reduce the tight-junction proteins between gut lining cells, loosening the gut barrier, and shift the makeup of gut bacteria. Its link to irritable bowel syndrome is so far only an association, not established cause and effect.

Milk Thistle Glutathioneweak · 2 cited

In cell and animal studies, silybin partly restores depleted glutathione; but after it is swallowed, very little reaches the blood, and most of what does is in conjugated form, so whether this step can happen in a person is an open question.

Nasal Breathing & Mouth Taping Respiratoryweak · 2 cited

The paranasal sinuses continuously produce a little nitric oxide (NO), which travels down into the lungs with each breath in and slightly widens only the small vessels beside the alveoli that have just received fresh air, so air and blood flow are matched more closely. In the small experiments of Lundberg 1996, healthy people had higher blood oxygen tension breathing through the nose than through the mouth, and arterial oxygen rose in intubated patients when air from their own noses was fed back in; how much this contributes in everyday breathing is still unsettled, and mouth breathing bypasses this nitric oxide altogether.

Palpitations Strokeweak · 2 cited

One kind of palpitation is atrial fibrillation, a beat that is irregular with no pattern, and it raises the risk of stroke. In a smartwatch study of 419,000 people, 34% of those who got an irregular-pulse alert and later wore an ECG patch had atrial fibrillation. So a watch alert is worth an ECG, and a newly irregular heartbeat with no pattern that you feel yourself means seeing a doctor the same day.

Picky eating Ironweak · 2 cited

Picky eaters eat little meat, so iron and zinc are easy to run short of: in the UK ALSPAC cohort, persistently picky children ate about 40% less carcass meat and had lower iron and zinc intakes. Toddlers grow fast and need plenty of iron, and after age 1 cow's milk should stay under 500 mL a day. Only a blood test shows whether a child is short of iron; whether to supplement is for a pediatrician to decide.

Power and jumping Knee Painweak · 3 cited

Pain between the kneecap and the shin is often linked to repeated running and jumping, and is commonly called jumper's knee. In a cohort of young volleyball players, the more hours they trained, the higher their risk of jumper's knee, an observed association; stiff landings raise the impact, and teaching people to bend the hips and knees together and land on the front of the foot clearly lowers it.

Power and jumping Youth & adolescent trainingweak · 1 cited

Children can do jump training too. A systematic review of 7 studies found that children aged 5 to 14 clearly improved their running and jumping after jump training, and that it was safe when parents consented, the children agreed to take part and safety rules were built in; the studies, though, were all of low quality.

Pregnancy + exercise Training on short sleepweak · 2 cited

In the months after birth when you get up at night to feed, sleep is broken into pieces, and exercise then helps more than the body alone. The American College of Obstetricians and Gynecologists writes that physical activity can be an important factor in preventing postpartum depression, and in a meta-analysis of 12 controlled trials, exercise during pregnancy and after birth lowered postpartum depressive symptoms, more so in mothers who already had them. Returning to training after birth follows the postnatal check and starts again from the lightest level.

Quercetin Hallmarks of Agingweak · 1 cited

Quercetin's most interesting modern direction is clearing senescent cells (as a senolytic): damaged cells that did not finish dying get stuck in a state where they neither divide nor die, and keep releasing inflammatory factors that add to chronic inflammation throughout the body. Dasatinib plus quercetin (D+Q) is one of the few such approaches to reach human trials, and a preliminary trial in people with diabetic kidney disease saw fewer senescent cells; it remains an experimental treatment.

Rhodiola rosea Burnout Syndromeweak · 1 cited

In one of the few randomized trials in burnout (Olsson 2009), 60 people with fatigue from long-term stress took a standardized extract for 4 weeks and improved more than placebo on a burnout scale and several attention measures, though both groups improved markedly on placebo and the trial was small and single-center. At most it is an add-on; it cannot replace changes to workload and recovery, which are what actually work.

Running form + shoes Running for beginnersweak · 2 cited

The evidence that changing your running form or shoes prevents injury is weak. For a beginner, injury prevention rests on building up volume gradually and adding strength training, which gives tendons and bone time to adapt; putting all your attention on shoes crowds out what matters more.

Sedentary office body Varicose veinsweak · 2 cited

Standing still, pressure in the foot veins can reach 80 to 90 mmHg, and sitting still leaves the calf muscle pump just as switched off; once you walk, the calf muscles squeeze blood upward and, with working valves, bring it below 30 mmHg. That is why long periods of standing or sitting are listed as a risk factor for varicose veins, and getting up to walk a few steps, or raising your feet when you sit, is the usual advice.

Sleep Architecture & Sleep Debt Growing tallerweak · 2 cited

Growth hormone's largest daily release follows deep sleep after falling asleep: in two small studies in young adults, delaying sleep delayed the peak, and reversing sleep and waking by 12 hours moved the peak with sleep. Growth hormone drives the growth plates, but the step from sleep to a child's final height has not been measured directly.

Starting from zero Sedentary office bodyweak · 2 cited

People who sit all day can slip movement into the sitting itself, not only into a short stretch after work. In a small randomized crossover trial, overweight adults who got up and walked for 2 minutes every 20 minutes of sitting had about a 24% smaller blood-sugar response after a meal, and the American College of Sports Medicine says that breaking up sitting with frequent short bouts of standing and activity brings health benefits, even for people who already exercise.

Starting from zero Neck Painweak · 1 cited

A neck and shoulders stiff from long sitting will not be fixed by a few more steps. For chronic mechanical neck pain, strength training for the neck, shoulder blades and upper limbs, combined with stretching, brings a moderate reduction in pain that holds at longer follow-up, and these exercises need no gym equipment.

Starting from zero DOMS sorenessweak · 3 cited

When you are just starting or try a new movement, muscles that get sore a day or two later and recover within a few days are normal delayed-onset muscle soreness. A few cases are not: unaccustomed exercise done too hard all at once can trigger rhabdomyolysis, and pain and swelling far out of proportion to the training, weak muscles or dark urine mean going to the emergency department immediately.

Starting from zero Training injuriesweak · 2 cited

When you add load from zero, no percentage holds for everyone: in a randomized trial of 532 novice runners, a plan built on adding no more than 10% a week did not reduce injuries. What survives is the principle of adjusting to your habitual activity and your response to exercise and raising intensity and volume gradually, which the American College of Sports Medicine says may reduce the risks of exercise.

Starting solids Picky eatingweak · 3 cited

The tastes and textures a baby practices when starting solids carry on into the toddler years. After 10 tries of the same vegetable, babies were all eating more of it; in an English cohort, children first given lumpy food after 9 months ate less fruit and vegetables at 7 and had more feeding problems, an observational finding. A review likewise lists lumpy foods introduced late and pressure to eat among the causes of picky eating.

Taurine · anti-aging?Hallmarks of Agingweak · 3 cited

A 2023 study found that blood taurine falls with age in mice, monkeys and humans, and restoring it in middle-aged mice extended median lifespan by about 10–12%. But working in mice is not the same as working in people: the human data are only correlations, and a 2025 study of 137 men found no link between taurine levels and age.

Tongkat Ali Testosterone & Agingweak · 3 cited

Tongkat ali is thought to affect testosterone in two ways: by boosting testosterone production in the testes and inhibiting its conversion to estrogen, and by lowering cortisol a little. These mechanisms come mostly from cell and animal studies. In people, a meta-analysis of 5 randomized trials reported higher total testosterone, most firmly in men whose testosterone was low; the often-quoted Tambi 2012 study had no control group.

Training injuries Warm-up & cool-downweak · 2 cited

The part of a warm-up worth doing is raising body temperature and rehearsing the movements, which makes the session better. What actually prevents injury is something else: in a meta-analysis of randomized trials, strength training cut sports injuries by about two thirds, while stretching showed no effect. You also have to keep the pace of increasing your training in check.

Training on short sleep Starting from zeroweak · 2 cited

The talk test and perceived effort read how the body is responding right now, not a fixed pace or weight, so on short sleep they scale the intensity down on their own. In one experiment, 11 men ran for 30 minutes at their own pace after 30 hours awake; their perceived effort was about the same as after normal sleep, yet they covered less distance. If you can still talk in full sentences fairly comfortably, you are below the ventilatory threshold.

Training on short sleep Training injuriesweak · 2 cited

On short sleep, reaction and skill decline first, which makes mistakes in contact and complex movements more likely; that is the reason to drop contact, technical work and heavy sets close to failure first on a short-sleep day. In a retrospective study of 112 adolescent athletes, those who slept less than 8 hours a night on average were 1.7 times as likely to have had an injury; that is an observed association and cannot show that short sleep caused it.

Vestibular System Vitamin Dweak · 3 cited

A Korean multicenter randomized trial (Jeong 2020) gave vitamin D and calcium only to people with BPPV whose repositioning had worked and whose blood vitamin D was low (25(OH)D below 20 ng/mL, that is, 50 nmol/L), and recurrence over a year fell from 46.7% to 37.8%. The trial did not test whether people who are not short of vitamin D benefit; repositioning is still the treatment itself, and the result does not carry over to falls or fractures.

Vitamin A Respiratoryweak · 2 cited

Vitamins C and E and the carotenoids together form the lung's antioxidant network, but the benefit from the diet as a whole is modest. A single nutrient at a high dose backfired: in the ATBC trial, beta-carotene supplements raised lung cancer in smokers by 18%.

Vitamin B6 Menstrual Cycleweak · 2 cited

Vitamin B6 has some evidence for easing premenstrual symptoms, but it is limited. It is also one of the few water-soluble vitamins that harms when overdone: taking more than 100 mg a day long term can cause peripheral neuropathy, meaning numbness and tingling in the hands and feet. Keep both the benefit and the risk in mind.

Vitamin C Cold, Flu & Allergyweak · 1 cited

Vitamin C against colds is a widely repeated claim, but in the trials pooled by a Cochrane systematic review, long-term supplements did not reduce colds in the general population; regular supplements shortened colds in adults by only about 8%, and starting once symptoms appear did essentially nothing.

Vitamin E Heartweak · 2 cited

After vitamin E stops a free radical in a cell membrane, it becomes a tocopheroxyl radical itself and needs vitamin C to restore it. Large trials of vitamin E supplements found no cardiovascular benefit; one explanation from test-tube work is that high-dose vitamin E on its own lets these radicals build up, but that has not been measured directly in people.

Water & Electrolytes Migraineweak · 2 cited

Dehydration may trigger migraine in some people, but migraine itself is a neurovascular disorder in which a signaling molecule called CGRP is a key link, and a newer class of drugs for preventing and treating attacks is designed to target it. Relying on drinking more water alone misses the treatments that actually work.

Zinc Cold, Flu & Allergyweak · 1 cited

Zinc lozenges may shorten a cold by about two days, but a Cochrane systematic review rated the certainty of that evidence as low, with results varying widely between studies, and side effects such as nausea and a bad taste in the mouth are common; for preventing colds, zinc does almost nothing.