Study archive · page 23

A sweep of 158 studies compiled for the International Menopause Society found moderate-certainty evidence that black cohosh eases hot flushes and menopausal symptoms, Chinese herbal medicine helps menopausal symptoms, sleep and blood pressure, and vitamin D reduces fracture risk. Most other complementary therapies for menopause rest on low or very low certainty evidence.

⚠What it shows: A serious map of the evidence rather than proof any remedy works: it pooled 158 studies to guide international menopause recommendations, but most of the underlying trials were low quality. The few therapies that reached moderate certainty could still shrink under better trials.Systematic review · Climacteric

Women who tested positive for thyroid peroxidase antibodies around pregnancy had a 52% higher risk of perinatal depression, in results pooled from 11 studies of 10,559 women.

⚠What it shows: Strong enough to take seriously, but it shows a link, not a cause: results pooled from 11 studies of 10,559 women, and the studies disagreed with each other to a moderate degree. Nobody has yet tested whether the antibody itself drives the depression risk or is simply a marker of something else.Study · J Perinat Med

In pooled data from 59 trials of 4,225 postmenopausal women, aerobic training was linked to lower blood pressure, resting heart rate, waist size, body fat and LDL cholesterol. Unexpectedly, light intensity, not moderate or vigorous, showed benefits for blood glucose and triglycerides.

⚠What it shows: Treat gently: although results were pooled from 59 trials in 4,225 women, the reviewers rated the certainty of the evidence as very low for every outcome, and the intensity findings come from subgroup comparisons that still need direct testing.Meta-analysis · Womens Health (Lond)

A meta-analysis of 8 studies covering 325 women found that oral contraceptive pill use had no significant effect on gains in muscle size, strength or power from resistance training.

⚠What it shows: A solid null as far as it goes: results pooled from 8 studies and 325 women all point the same way, but every study looked at oral pills only, so it says nothing about implants, injections or hormonal coils.Meta-analysis · Sports Med

Resistance training improved bone mineral density at the lumbar spine, femoral neck and total hip in a pooled analysis of 17 trials with 690 postmenopausal women. Training at 70% of one-rep max or heavier, three times a week, sustained for 48 weeks or more, looked like the most effective pattern.

⚠What it shows: Encouraging but not the final word: results pooled from 17 trials that assigned 690 postmenopausal women at random showed clear gains at the spine and hip, but the trials disagreed with each other considerably at those sites. The ideal mix of intensity and frequency comes from smaller subgroup comparisons, so hold that part loosely.Meta-analysis · J Orthop Surg Res

Across 106 trials in 8,642 adults with overweight or obesity, long-term exercise of any structured mode lowered circulating inflammatory markers including CRP, IL-6, TNF-α and leptin. The benefit tracked with improvements in VO2max, and spontaneous physical activity alone was not effective.

⚠What it shows: A strong signal: results pooled from 106 trials in 8,642 adults with overweight or obesity, though the trials varied widely in design and length. The fitness link comes from statistical analysis across studies rather than a direct head-to-head test.Meta-analysis · Obes Rev

A meta-analysis of 25 trials in 1257 people with type 2 diabetes found exercise training raised adiponectin and lowered inflammatory markers, fasting insulin and insulin resistance, yet lipid profiles did not improve.

⚠What it shows: Encouraging but not final: results pooled from 25 trials in 1257 people with type 2 diabetes pointed the same way, but the studies disagreed with each other considerably and the authors want more trials before calling it settled.Meta-analysis · Biol Res Nurs

Pooled results from six randomised trials in 6266 adults with overweight or obesity found once-weekly tirzepatide beat both placebo and GLP-1 drugs for weight loss at every dose tested, with high-certainty evidence for achieving at least 15% weight loss. Gut side effects matched the GLP-1 drugs but were significantly more common than with placebo.

⚠What it shows: About as solid as weight-loss drug evidence gets: results pooled from six trials covering 6266 adults, rated high certainty for reaching at least 15% weight loss. The open questions are how much lean tissue goes with the fat and how well people tolerate the gut side effects long term.Meta-analysis · J Obes

In adults with type 2 diabetes, structured exercise training was associated with a 0.67% drop in HbA1c versus control, and programmes over 150 minutes per week were linked to a 0.89% reduction against 0.36% for shorter ones. Advice to be active was only associated with lower HbA1c when paired with dietary advice.

⚠What it shows: Strong by weight of numbers: results pooled from 47 trials with 8538 people with type 2 diabetes, all lasting at least 12 weeks. The trials varied a great deal in design and populations, so the percentage drops are averages across very different programmes rather than a guarantee for any one person.Meta-analysis · JAMA

A pooled analysis of 28 randomised trials in 1833 adults found intermittent fasting reliably reduced body weight and BMI at every age, but fat-free mass fell in younger and older adults and LDL cholesterol rose. The authors rate the certainty of evidence low to very low and call the age-specific patterns hypothesis-generating.

⚠What it shows: Treat this as a set of leads rather than verdicts: results pooled from 28 trials covering 1833 adults, yet the authors themselves rate the certainty low to very low. The age-by-age patterns, including the LDL rise, are flagged as hypothesis-generating and need larger trials.Meta-analysis · Nutrients

Time-restricted eating on its own cut body weight by 1.59 kg and fat mass by 0.93 kg versus no restriction across 20 randomised trials, but adding deliberate calorie restriction on top delivered no extra weight loss. Both approaches also trimmed around half a kilogram of fat-free mass.

⚠What it shows: Solid pooled evidence: results pooled from 20 trials in 1242 adults all pointed the same way. The catch is the average extra loss was 1.59 kg, and some of it was fat-free mass rather than fat.Meta-analysis · Int J Behav Nutr Phys Act

Pooled studies found time-restricted eating produced a 2.32% weight loss in overweight and obese adults, but the loss came mainly from lean mass rather than fat mass, and LDL cholesterol rose in the fasting groups.

⚠What it shows: Worth taking seriously but not as settled: results pooled from randomised trials and some studies that did not assign people at random, in overweight and obese adults. The authors themselves urge caution for anyone with high cholesterol or already low muscle mass.Meta-analysis · Crit Rev Food Sci Nutr

Across 28 randomised trials in 3,460 middle-aged and older adults, aerobic exercise ranked as the most effective exercise type for improving overall sleep quality scores, while yoga ranked best for sleep efficiency, sleep duration and daytime function.

⚠What it shows: A credible ranking rather than a race result: it pools 28 trials in 3,460 middle-aged and older adults, but many comparisons between exercise types are indirect, so which one wins is a probability estimate rather than a head-to-head verdict.Meta-analysis · J Clin Sleep Med

Across 16 randomised trials in adults with overweight or obesity, alternate-day fasting, time-restricted eating and the 5:2 diet left overall sleep quality scores no different from ordinary dieting or a usual diet, with only slight delays in falling asleep on some measures.

⚠What it shows: Reassuring but thin: 16 trials pooled together, most of them small and run on different fasting schedules, so the slight delays in falling asleep could easily wash out with better data. The authors themselves call for more careful studies.Meta-analysis · Nutr Metab Cardiovasc Dis

Pooled results from 24 randomised trials in 1594 people suggest pycnogenol, a supplement, may modestly improve several cardiometabolic markers, lowering fasting blood glucose, blood pressure, BMI and LDL cholesterol while raising HDL cholesterol.

⚠What it shows: Promising but not settled: results pooled from 24 trials in 1594 people all pointed the same modest way, yet the authors themselves say longer, better-designed trials are needed to confirm the effects and pin down dose and duration.Meta-analysis · Pharmacol Res

L-theanine, an amino acid found in tea, modestly improved self-reported sleep quality, sleep onset and next-day function in a meta-analysis pooling 18 randomised trials with 897 participants, though few trials tested it on its own rather than in blends.

⚠What it shows: Promising but not proven: results pooled from 18 trials in 897 people showed small improvements that were all self-reported, and few trials tested pure L-theanine rather than mixtures, so it is hard to say the amino acid alone deserves the credit.Meta-analysis · Sleep Med Rev

In a meta-analysis of 10 randomised trials with 376 people aged 26 or under with clinically elevated symptoms, resistance training produced large reductions in both depression and anxiety symptoms, with high-certainty evidence for depression.

⚠What it shows: One of the stronger exercise and mood findings: results pooled from 10 trials where 376 young people were assigned at random, rated high certainty for depression, though the size of the benefit varied a lot between trials and none tracked whether it lasted after the programme ended.Meta-analysis · Early Interv Psychiatry

Probiotics and synbiotics modestly reduced anxiety scores across 29 randomised trials involving 2035 people, while prebiotics showed no significant effect. The pooled effect was small, and the authors say it is too early to call them a treatment for anxiety.

⚠What it shows: Broad but modest: results pooled from 29 trials in 2035 people found lower anxiety scores with probiotics and synbiotics, yet the effect was small and nobody agrees on the best strain, dose or length of treatment. Prebiotic and synbiotic trials were also thin on the ground.Meta-analysis · J Affect Disord

Pooled imaging from 14 studies shows the thoracolumbar fascia, the broad connective tissue sheet of the lower back, is thicker, stiffer and more echogenic in people with low back pain than in pain-free controls. Greater fascial thickening also correlated with higher pain ratings.

⚠What it shows: A real and consistent difference, but a snapshot: results pooled from 14 imaging studies comparing people with and without back pain cannot say whether the fascia changes cause the pain or follow from it. The stiffness and density findings also rest on just 3 studies each.Systematic review · Sports Med Open

Exercise therapy meaningfully reduced pain and disability and improved both physical and mental quality of life in adults aged 60 and over with chronic low back pain, across 18 randomised trials involving 989 people. Effects on mobility were less certain.

⚠What it shows: Strong enough to matter: results pooled from 18 trials in 989 adults aged 60 and over, and the included studies were of relatively high quality. The mobility findings were shakier and the authors say more trials are needed to confirm them.Meta-analysis · J Orthop Surg Res

Strength training is powerful injury prevention: across trials in 7738 athletes aged 12 to 40, structured strength work cut acute and overuse sports injuries to roughly a third of the risk, and every 10% increase in strength training volume trimmed injury risk by more than four percentage points.

⚠What it shows: About as solid as sports science gets: results pooled from six trials that assigned 7738 athletes aged 12 to 40 at random, with consistent findings, high compliance and no sign that negative results were left unpublished. The programmes and sports varied a lot, so no single routine was proven to be the best one.Meta-analysis · Br J Sports Med

A meta-analysis of 160 randomised trials in 7487 adults without cardiovascular disease found exercise training improved cardiorespiratory fitness, lipid profiles and insulin measures, with larger effects in people under 50, men, and those with type 2 diabetes, hypertension, dyslipidaemia or metabolic syndrome.

⚠What it shows: About as broad as exercise evidence gets: results pooled from 160 trials in 7487 adults without heart disease. The programmes varied enormously, so exactly which type or dose of exercise drives each marker cannot be pinned down from this.Meta-analysis · J Am Heart Assoc

In pooled trial data covering 3451 people, those taking probiotics were less likely than those on placebo to catch at least one acute upper respiratory infection, and antibiotic prescriptions for these infections fell too. How long an infection lasted once caught did not change.

⚠What it shows: Reasonably solid: results pooled from 10 trials in 3451 people, with side effects no worse than placebo and mostly minor stomach upsets. Some of the trials disagreed with each other and none covered older adults, so the true size of the benefit is uncertain.Meta-analysis · Cochrane Database Syst Rev

Weight-loss smartphone apps showed no clear benefit in a sweep of 18 trials with 2703 adolescents and adults with overweight or obesity: at 12 months apps made little to no difference to body weight or BMI compared with minimal support, and results at 24 months looked no better.

⚠What it shows: A thorough sweep of all the studies, 18 trials and 2703 people, found no convincing benefit, though certainty ranged from moderate down to very low because the apps varied enormously in features and content. With 34 more trials under way, the verdict could still shift within a couple of years.Meta-analysis · Cochrane Database Syst Rev