Does shilajit actually work as a supplement?
Shilajit has shown positive results for specific purposes, such as testosterone in men aged 45 to 55 and bone healing, but it does not work for everyone or for everything. Do not use it during pregnancy.
Shilajit has its strongest evidence base in the area of testosterone in older men. In a double-blind placebo-controlled study in healthy men aged 45 to 55, total testosterone, free testosterone, and the adrenal hormone DHEAS rose significantly after 250 mg twice daily for 90 days. Gonadotropic hormones remained stable, suggesting the mechanism does not run through the brain. A review of 52 studies on 27 testosterone boosters puts this in perspective: most supplements fail. Purified shilajit extract is described in that review as 'possibly effective', but specifically for men with late-onset testosterone deficiency, not for healthy young men.
In the area of recovery and connective tissue, there are two findings. In 160 people with a shinbone fracture, the bone healed in an average of 129 days with shilajit versus 153 days with placebo, a statistically significant difference. In a study of recreationally trained young men, shilajit (500 or 1000 mg per day for 8 weeks) increased a blood marker indicating the production of type 1 collagen. Whether that actually results in stronger bones or tendons has not yet been demonstrated.
For energy, fatigue, and sperm production, there are indications from animal and smaller human studies, but the evidence is still too thin for firm conclusions. Laboratory research shows antiviral activity against a number of viruses, but whether that has any effect in humans has not been investigated.
On the topic of safety, there is good news for healthy adults: no serious side effects have been demonstrated with normal use. However, there is one reported case of a 37-year-old pregnant woman who developed severe high blood pressure and low potassium levels after using shilajit. She recovered after stopping. Use during pregnancy therefore appears to carry risks; if so, be sure to discuss it with your doctor.
The testosterone effect rests on one double-blind placebo-controlled study and a review of 52 studies on testosterone boosters. Bone healing was investigated in 160 people in a double-blind placebo-controlled study. The collagen finding and the combination study for metabolic syndrome are also controlled but smaller in design. The claims about energy and fertility come from one review article that summarises animal and human studies, without further specification of the individual studies. The safety concern in pregnancy is based on a single case, which limits certainty but does make the signal worth taking seriously.
Is spermidine from food just as good as a supplement?
There is no evidence that a spermidine supplement does the same thing as spermidine from food; supplements may be neutralised by the body and the effective dose in humans is unknown. If you want to increase your spermidine intake, opt for spermidine-rich foods.
Does ashwagandha really work against stress?
Ashwagandha demonstrably lowers the stress hormone cortisol, but whether it also makes you actually feel less stressed has not been convincingly proven in independent research. Short-term use of up to around 12 weeks appears safe, but too little is known about long-term use to be certain.
Is taking a stack of supplements at the same time smart or actually dangerous?
Whether a supplement stack is smart or dangerous depends on which substances you combine and whether you also use medications. Always tell your doctor or pharmacist what you are taking, and be especially cautious with St. John's wort and goldenseal.
Is colostrum (beestings) a worthwhile supplement?
For now, colostrum has the strongest indications as an aid against respiratory tract infections in athletes; for most other claims the evidence is too thin or too contradictory to recommend anything.
Do functional mushrooms like reishi and cordyceps actually work?
Medicinal mushrooms such as reishi show promising effects in the laboratory, but convincing evidence in humans is still lacking. Also check the species: cordyceps of the species Cordyceps militaris (the form most supplements use) is not authorised in the EU and may not be sold — the Dutch NVWA removed these products from the market in 2025. If you use medications, always consult your doctor first.
Does ergothioneine work as a longevity supplement?
Ergothioneine shows a positive signal in a small study of older adults with memory complaints, but it is too early for firm recommendations. Eating mushrooms is a risk-free way to obtain the compound; a supplement is worth considering only once larger studies provide greater clarity.