Not supportedUp to 44% of people carry an MTHFR gene variant that stops them using folic acid properly, linked to problems such as anxiety and depression, so a gene test plus methylated vitamins is worthwhile.
MTHFR variants are common, but medical geneticists conclude there is no good evidence that testing for them helps people's health; folate, B12 or homocysteine blood tests are used when a problem is suspected.
American College of Medical Genetics and Genomics practice guideline (Hickey et al., Genetics in Medicine, 2013; addendum 2020)
UnprovenHydrogen water is a powerful antioxidant that boosts energy and can lengthen telomeres.
Studies are small and early; the telomere result came from a small pilot trial part-funded by a seller, and a 2023 review suggests tablets dissolved in water may deliver only low doses.
Jonathan Jarry, McGill Office for Science and Society, 2025; Zanini et al., 2021; Johnsen et al., Molecules, 2023
Not supportedWalking barefoot on the earth (grounding) changes the body's electrical charge and improves blood flow and oxygen uptake.
Evidence for these effects comes from small, weak studies; time outdoors and gentle movement are fine, but the electrical explanation is not established.
Jonathan Jarry, McGill Office for Science and Society, 2025
Partly supportedWim Hof-style breathing with breath holds improves circulation and resets the nervous system.
A lab study showed it can change the immune response, but a systematic review of eight small trials found mixed results apart from effects on inflammation. Hyperventilation and breath holds can cause fainting, so it must never be done in or near water or while driving.
Kox et al., PNAS, 2014; Almahayni & Hammond, PLOS ONE, 2024
Partly supportedA few minutes of cold water a day lowers stress and strengthens the body.
A review of 11 trials found possible benefits for stress, sleep and quality of life, but the studies were few and small. Sudden cold can strain the heart, which matters for older adults.
Cain et al., PLOS ONE, 2025
SupportedMorning sunlight soon after waking helps set the body clock and improves energy and sleep.
Bright daytime light, especially in the morning, supports circadian rhythm and sleep; his mitochondria explanation is less established than the body-clock effect.
Brown et al., PLOS Biology, 2022