A 2015 meta-analysis by researchers at Brigham Young University confirms that loneliness is indeed as deadly a risk factor as obesity, smoking or a sedentary lifestyle.

Source: https://www.salon.com/2023/04/01/loneliness-isnt-just-for-your-mental-health--it-can-compromise-your-immune-system/

A meta-analysis of studies on loneliness done at BYU found that loneliness increases the odds of an earlier death by 45%, the same impact as smoking 15 cigarettes a day.

Source: https://www.deseret.com/opinion/2023/3/20/23645047/religion-belonging-gen-z-mental-health

A network meta-analysis on the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus.

Source: https://www.healthcanal.com/nutrition/keto-diet-meal-plan

Effects of β-alanine supplementation on exercise performance: a meta-analysis.

Source: https://www.healthcanal.com/life-style-fitness/exercise/best-pre-workout-for-crossfit

January’s NIH meta-analysis shows that taking it “results in a decreased risk of death and ICU admission.”

Source: https://pjmedia.com/vodkapundit/2023/02/03/want-to-avoid-the-icu-for-covid-just-take-this-one-little-pill-n1667558

The closest we can come is a 2010 meta-analysis by the Dutch academic Prof Renske Keiser, which suggested that only 10% of childless women actively chose not to become mothers.

Source: https://pjmedia.com/culture/benbartee/2023/02/23/study-a-shocking-percentage-of-childless-women-actually-wanted-kids-n1673115

The role of probiotics in the treatment of adult atopic dermatitis: a meta-analysis of randomized controlled trials.

Source: https://www.healthcanal.com/health/digestion/seed-probiotics-review