Topic
Supplements
Pills, powders and compounds: vitamins and minerals, performance and longevity supplements, herbals, and safety.
Vitamin D at 1,600 or 3,200 IU a day did not cut fractures in older adults, most of whom were not deficient
University of Eastern Finland researchers gave 2,495 older adults a placebo or one of two vitamin D3 doses for five years. The higher dose matched placebo on fractures; the lower one came with an unexplained excess.
Sep 14, 2026
A selenium supplement lowered long-term blood sugar by 1.2 points in eight weeks
That is a drug-sized change from a mineral sold in pharmacies. It came from one small trial in patients with diabetic nerve damage, and the size of the effect is the reason to be careful rather than excited.
Sep 6, 2026
Vitamin K from leafy greens tracked 14% less dementia over 28 years; the other form went the wrong way
Vitamin K comes in two forms and the supplement industry prefers K2. Following 54,968 Danes for up to 28 years, higher K1 intake tracked lower dementia risk while higher K2 tracked higher, which is the opposite of the marketing.
Sep 1, 2026
Zinc cut infections by 38% in young children with sickle cell disease in a Ugandan trial
Zinc is one of the most-bought supplements in the world and one of the least-tested against hard outcomes. A JAMA trial randomized 100 Ugandan children under five and counted every infection for six months.
Sep 1, 2026
Garlic lowered average blood sugar by half a point across 27 trials, but fasting glucose barely moved
27 randomized trials and 1,619 people. Garlic supplements lowered long-term average blood sugar by about half a percentage point, a shift comparable to some drugs. Fasting glucose barely moved, which is hard to square.
Aug 25, 2026
Strawberry leaf extract failed its pre-planned memory test, then reported a win anyway
109 older adults took strawberry leaf extract or a placebo for 12 weeks. The pre-planned analysis found nothing, on memory or anything else. The paper is titled 'Enhanced memory function and reduced perceived stress'.
Aug 24, 2026
Vitamin D missed its target in depressed young people
A trial gave 4,800 IU a day for eight weeks to young people who had both major depression and low vitamin D, the group where it should work best. Depression scores did not separate from placebo. Anxiety did.
Aug 16, 2026
Calcium supplements: uses, evidence, dosing and safety
Calcium is taken for bones, and a 2026 BMJ review found little to no benefit for fractures or falls. Its best evidence is somewhere almost nobody looks: preventing pre-eclampsia in pregnancy.
Aug 6, 2026
Collagen: uses, evidence, dosing and safety
Collagen is sold for skin and works better for joints. A 2025 review found that industry-funded studies showed a skin benefit and independently funded ones did not.
Aug 6, 2026
Inositol: uses, evidence, dosing and safety
Inositol does two things, and it does them better than most of the supplement aisle: it lowers the risk of gestational diabetes, and it improves hormone markers in polycystic ovary syndrome.
Aug 6, 2026
Iron supplements: uses, evidence, dosing and safety
Iron is the one supplement where taking it without a blood test is genuinely unwise. It fixes a diagnosed deficiency well, and the same dose in the wrong person accumulates with nowhere to go.
Aug 6, 2026
Magnesium: uses, evidence, dosing and safety
Magnesium is bought mostly for sleep, which is its weakest evidence. Its real results are elsewhere: blood pressure in people who are short of it, migraine frequency, and heart rhythm after surgery.
Aug 6, 2026
Omega-3 and fish oil: uses, evidence, dosing and safety
Omega-3 has the strongest single result of any supplement on this site, a high-certainty 15% cut in triglycerides. It also has a dose-dependent harm signal that almost nobody selling it mentions.
Aug 6, 2026
Probiotics: uses, evidence, dosing and safety
Probiotics have one strong result, halving antibiotic-related C. difficile diarrhea, and a long list of weaker ones. Cochrane noted probiotic-company funding in 28 of the 47 trials it pooled.
Aug 6, 2026
Vitamin C: uses, evidence, dosing and safety
Vitamin C has been tested against the common cold for sixty years and the answer is still a shrug: it may shorten one slightly, and taking it once a cold has started does almost nothing.
Aug 6, 2026
High-dose vitamin D did not slow advanced bowel cancer
A 455-patient phase 3 trial run through the US National Clinical Trials Network added high-dose vitamin D3 to standard chemotherapy for metastatic colorectal cancer. It did not delay progression.
Aug 6, 2026
Vitamin D: uses, evidence, dosing and safety
Vitamin D is the most-studied supplement there is, and the pattern across thirteen uses is almost always the same: correcting a deficiency helps, and adding more on top of enough does not.
Aug 6, 2026
Vitamin K status did not protect bone in a VITAL analysis
Vitamin K is sold as the partner vitamin D needs for bones. In 771 participants of the VITAL trial, higher vitamin K status did not slow two-year bone loss or improve what vitamin D did.
Aug 6, 2026
Coenzyme Q10: uses, evidence, dosing and safety
CoQ10 has decent evidence for the serious condition almost nobody buys it for, and it fails at the one thing almost everybody buys it for. Statin muscle pain is the claim that does not hold up.
Aug 5, 2026
NAC: uses, evidence, dosing and safety
NAC is a hospital antidote sold as a supplement, and the two are not the same claim. It saves lives in paracetamol overdose. For almost everything it is marketed for, the evidence is thin or uncertain.
Aug 5, 2026
Selenium: uses, evidence, dosing and safety
Selenium is essential, and supplementing it when you are not short of it is the clearest honest-no in the supplement aisle. Cochrane found no cancer benefit at high certainty, plus signals of harm.
Aug 5, 2026
Ashwagandha: uses, evidence, dosing and safety
Ashwagandha has real evidence for stress and sleep, thinner evidence for strength, and a liver problem that arrived in 2017. The list of people who should avoid it is unusually long, and now includes thyroid patients.
Aug 3, 2026
Berberine: uses, evidence, dosing and safety
Berberine is sold as nature's Ozempic, a comparison it does not earn. It genuinely lowers blood sugar and some lipids, on small and limited trials; the weight-loss claim driving the marketing is the weakest part.
Aug 3, 2026
Turmeric and curcumin: uses, evidence, dosing and safety
Curcumin barely absorbs, and the high-absorption forms built to fix that are the ones LiverTox links to liver injury. Knee osteoarthritis is the one solid use; the rest is thinner than the shelf suggests.
Aug 3, 2026
Vitamin B12: uses, evidence, dosing and safety
B12 inverts the usual advice here. Most people do not need it, but vegans, older adults and anyone on long-term metformin do, because untreated deficiency damages nerves in ways that may never reverse.
Aug 3, 2026
Zinc: uses, evidence, dosing and safety
Zinc has three evidence-backed uses: a lozenge for an adult's cold, a high-dose formula for existing macular degeneration, and children in places where deficiency is common. The daily immune capsule is not one of them.
Aug 3, 2026
A vitamin B3 supplement tracked far less glaucoma in at-risk eyes
Among 2,920 matched patients with high eye pressure, those taking nicotinamide developed glaucoma at 3.5% against 9.0%. The design cannot prove the supplement caused it.
Aug 2, 2026
Newborns who skipped vitamin K had triple the brain bleeds
A JAMA Pediatrics study of 2 million Swedish births found infants who did not get the vitamin K injection had higher odds of bleeding, and refusals have more than doubled since 2006.
Jul 28, 2026
Vitamin K2 slowed artery calcium in a two-year trial
A JAMA Cardiology randomized trial gave 180 patients with coronary artery disease vitamin K2 or placebo for two years and found calcium buildup progressed more slowly on the supplement.
Jul 26, 2026
Vitamin A, not D, tracked with better lungs in asthma
A Thorax study of 1,165 children and 1,041 adults with asthma found blood vitamin A levels tracked with better lung function, while vitamin D did nothing measurable in children.
Jul 26, 2026
US supplement use hit 60% as multivitamins fell and ashwagandha rose, across 25 years of data
A JAMA Network Open analysis of 63,442 adults across 25 years of national survey data found supplement use rose from 51% to 60%, with multivitamins falling and ashwagandha, collagen and elderberry rising.
Jul 25, 2026
Creatine: uses, evidence, dosing and safety
Creatine builds strength and lean muscle alongside resistance training, and the evidence is unusually strong and consistent. The kidney and hair-loss fears are not supported. Memory effects are promising but unsettled.
Jul 22, 2026
Fish oil reached the brain but didn't protect it
Researchers gave 365 older adults at higher risk of dementia high-dose fish oil or a placebo for two years. The omega-3 reached their brains, but memory, thinking and brain shrinkage were no different from placebo.
Jul 22, 2026
Phosphatidylcholine: uses, evidence, dosing and safety
Phosphatidylcholine's best-studied use is ulcerative colitis, where early promise did not survive the largest trials. Most other claims are weak, and gut bacteria turn its choline into TMAO, a debated heart concern.
Jul 22, 2026
Calcium and vitamin D did little for fractures or falls
A review of 69 randomized trials and more than 150,000 people found that for healthy older adults, calcium, vitamin D, or both together did little to prevent fractures or falls.
Jul 17, 2026