We looked, and the evidence does not back the claim: either it was tested and did not hold up, or nobody has tested it and nothing that was tested supports it.
Researchers took the top 16 testosterone and 16 erection supplements at the most popular US online retailers, pulled out their 37 ingredients and found 105 trials — but “no whole supplement products have published RCT evidence.” And reports of better libido fell 91% once untrustworthy reviews were filtered out.
In healthy men aged 19 to 39 the harmonised normal range is 264 to 916 ng/dL: the man at the top has three and a half times the man at the bottom. One reading under 300 is not a diagnosis; the guidelines ask for two early-morning tests and symptoms. And in 197,883 men, time of day moved the number more than decade of life did.
The US military now screens every service member over 30. The Endocrine Society’s guideline recommends against routine screening of men in the general population, at its strongest grade. And a glucose drink pushed 15% of men with normal testosterone into the hypogonadal range.
Pooled across 15 randomised trials of berberine and barberry, people lost 1.9 lb more than a comparison group. Semaglutide, in the trial that made it famous, beat placebo by 28 lb. Both are measured the same way, from the best evidence available for each.
Partially hydrogenated vegetable oil genuinely harmed people: when 11 New York counties restricted trans fat in eateries, hospital admissions for heart attacks and strokes fell an extra 6.2%. The FDA has since banned it. The fear outlived it and reattached to the oil that's left, which is usually soybean, as the ingredient list will tell you.
Researchers measured urine pH across citrus juices: orange juice alkalised it; lemon, grapefruit and lime didn't. The ritual picked the wrong fruit. For kidney stones, lemon juice is unproven: the one randomised trial of it that counted new stones could not rule out chance, and one in five got heartburn.
Canola is rapeseed bred low in erucic acid — the name literally means Canadian oil, low acid. The FDA ban people cite was against mustard oil, not this. Erucic acid does fatten animal hearts at high doses, which is why it was bred down to trace levels and is capped by law. And in 13 head-to-head trials, canola lowered LDL more than olive oil did.
In a review of human trials, cutting dietary linoleic acid by up to 90% did not move arachidonic acid in the blood, and three of four later studies we read agree, so the route usually blamed for inflammation mostly fails at step one. But two recovered BMJ trials found no mortality benefit, and in one, more men died on the oil. Here is the whole file, including what's wrong with both halves.
The whole scare rests on one 2009 study of 20 rugby players that measured DHT and never looked at anyone's hair. The 56% rise it found moved men from 0.98 to 1.53 nmol/L — the normal range is 0.8 to 3.5. In 2025 a trial finally examined hair directly for 12 weeks and found no difference at all.
On the same day in July 2023, IARC called aspartame 'possibly carcinogenic' — a hazard statement, third of four levels — and JECFA reaffirmed the safe daily intake, noting a 70 kg adult would need 9–14 cans of diet drink a day to exceed it. The press ran the first report. WHO's own nutrition director said safety is not a major concern at normal doses.