17 sources: 14 meta-analyses, 1 other design, 2 systematic reviews
Social · Concept
Quality vs. Quantity of Relationships
Quality of social contacts was more strongly associated with well-being in later life than quantity (Pinquart 2000); contact frequency showed a modest mortality association with null subgroups (Shor 2015); and larger network size a small protective association (Schutter 2022).
Beta content: this dimension's review set is version 0.9-beta and upgrades in place after the Round-2 internal reviews.
Beginner-friendlyAnywhere
Before you start
None, informational
When to seek a professional
- Persistent loneliness or isolation accompanied by low mood, hopelessness, loss of interest, or withdrawal lasting 2+ weeks: encourage contact with a primary care provider or mental health professional
- Thoughts of self-harm or that life is not worth living: direct to crisis line / emergency services immediately
Conceptual, no dose
For most adultsOlder adultsYoung adults
What the evidence says
What the sources say
The sources are meta-analyses of social relationships and mortality, disease and well-being. On quantity versus quality: Pinquart 2000 (meta-analysis) reports the quality of social contacts more strongly associated with subjective well-being in later life than quantity; Shor 2015 (meta-analysis) reports lower social-contact frequency associated with higher mortality (HR 1.13), with no significant relationship for males or for contact with family members, and concludes that contact frequency may not be as beneficial to health as previously thought; Schutter 2022 reports loneliness associated with mortality (HR 1.10) and larger network size protective (HR 0.96), with small effect sizes; Barth 2010 reports low functional social support relevant to coronary heart disease prognosis, with structural support effects unclear. On deficits and mortality or disease: Nakou 2025, Rico-Uribe 2018, Zhou 2023, Harris 2023, Wang 2023, Naito 2023 and Leigh-Hunt 2017 report loneliness and social isolation associated with higher all-cause mortality; Valtorta 2016 reports poor social relationships associated with coronary heart disease and stroke, and Meng 2024 with stroke and post-stroke mortality; Abreu 2024 reports worse social environment associated with cardiometabolic disease; Levis 2025 reports loneliness and low workplace social support associated with type 2 diabetes risk; Morina 2021 reports lack of social connection associated with a wide range of health outcomes; Yu 2023 reports social disconnection linked to higher all-cause mortality.
Common misconceptions
- Myth: more friends is always better. Reality: a small number of trusted ties can be enough.
- Myth: you must choose quality or quantity. Reality: both dimensions contribute independently.
What we won't claim
- Do not prescribe an optimal number of friends for any individual
- Do not imply large networks are inherently unhealthy
17 sources: 14 meta-analyses, 1 other design, 2 systematic reviews
- Agreement
- Direction recorded for 0 of 17 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- No source states a certainty rating.
What each source measured and concluded (17)
other design · 2023
Yu (2023) — Social disconnection and mortality: new evidence for old truths.
- What it measured
- All-cause mortality associated with social isolation and loneliness
- How it was read
- screened only, not extracted
meta-analysis · 2022
Schutter et al. (2022) — Loneliness, social network size and mortality in older adults: a meta-analysis
- What it measured
- Mortality risk associated with loneliness and social network size
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis
- Heterogeneity, as stated
- Loneliness associated with mortality (HR 1.10, 95% CI 1.06-1.14) and larger social network size protective (HR 0.96, 95% CI 0.93-0.99); large heterogeneity
meta-analysis · 2025
Nakou et al. (2025) — Loneliness, social isolation, and living alone: a comprehensive systematic review, meta-analysis, and meta-regression of mortality risks in older adults
- What it measured
- All-cause and cause-specific mortality associated with loneliness, social isolation, and living alone
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review, meta-analysis, and meta-regression
- Studies and participants, as stated
- 86 studies (from 11,964 identified)
- Heterogeneity, as stated
- Loneliness (HR 1.14, 95% CI 1.10-1.18), social isolation (HR 1.35, 95% CI 1.27-1.43), and living alone (HR 1.21, 95% CI 1.13-1.30) increased all-cause mortality; substantial heterogeneity
meta-analysis · 2024
Meng et al. (2024) — The impact of social relationships on the risk of stroke and post-stroke mortality: a systematic review and meta-analysis
- What it measured
- Risk of stroke and post-stroke mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis
- Studies and participants, as stated
- 19 studies; 1,675,707 participants
meta-analysis · 2023
Zhou et al. (2023) — A meta-analysis of the association between loneliness and all-cause mortality in older adults.
- What it measured
- Association between loneliness and all-cause mortality and its moderators
- How it was read
- screened only, not extracted
- What the review says it includes
- Meta-analysis
- Studies and participants, as stated
- 36 studies; 128,927 older adults
meta-analysis · 2018
Rico-Uribe et al. (2018) — Association of loneliness with all-cause mortality: A meta-analysis
- What it measured
- Association of loneliness with all-cause mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis (random effects)
- Studies and participants, as stated
- 35 articles; 77,220 participants
systematic review · 2017
Leigh-Hunt et al. (2017) — An overview of systematic reviews on the public health consequences of social isolation and loneliness.
- What it measured
- Public health consequences of social isolation and loneliness
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic overview (systematic review of systematic reviews)
- Studies and participants, as stated
- 40 systematic reviews
meta-analysis · 2023
Harris (2023) — Meta-analysis: Social Isolation, Loneliness Tied to Higher Mortality.
- What it measured
- Association of social isolation and loneliness with mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Meta-analysis (news/summary report of 90 prospective cohort studies)
- Studies and participants, as stated
- 90 prospective cohort studies; more than 2 million adults
meta-analysis · 2023
Wang et al. (2023) — A systematic review and meta-analysis of 90 cohort studies of social isolation, loneliness and mortality
- What it measured
- Association of social isolation and loneliness with all-cause, CVD, and cancer mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis of prospective cohort studies
- Studies and participants, as stated
- 90 prospective cohort studies; 2,205,199 individuals
meta-analysis · 2023
Naito et al. (2023) — Social isolation as a risk factor for all-cause mortality: Systematic review and meta-analysis of cohort studies
- What it measured
- All-cause mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis of cohort studies (random-effects)
- Studies and participants, as stated
- 1.30 million individuals
- Heterogeneity, as stated
- I²=76%)
meta-analysis · 2024
Abreu et al. (2024) — Associations between dimensions of the social environment and cardiometabolic health outcomes: a systematic review and meta-analysis
- What it measured
- Cardiometabolic disease (type 2 diabetes, CVD) incidence and prevalence
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis
- Studies and participants, as stated
- 281 studies; 1108 associations (384 in vote counting, 180 in 14 meta-analyses)
systematic review · 2021
Morina et al. (2021) — Potential impact of physical distancing on physical and mental health: a rapid narrative umbrella review of meta-analyses on the link between social connection and health
- What it measured
- Physical and mental health outcomes linked to social connection
- How it was read
- screened only, not extracted
- What the review says it includes
- Rapid narrative umbrella review of meta-analyses
- Studies and participants, as stated
- 25 meta-analyses (10 physical health, 15 mental health)
meta-analysis · 2016
Valtorta et al. (2016) — Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies
- What it measured
- Incident coronary heart disease (CHD) and stroke
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis of longitudinal observational studies
- Studies and participants, as stated
- 23 papers (16 datasets); 4628 CHD and 3002 stroke events
meta-analysis · 2000
Pinquart et al. (2000) — Influences of socioeconomic status, social network, and competence on subjective well-being in later life: a meta-analysis.
- What it measured
- Subjective well-being (SWB)
- How it was read
- screened only, not extracted
- What the review says it includes
- Meta-analysis
- Studies and participants, as stated
- 286 empirical studies
meta-analysis · 2010
Barth et al. (2010) — Lack of Social Support in the Etiology and the Prognosis of Coronary Heart Disease: A Systematic Review and Meta-Analysis
- What it measured
- Myocardial infarction (etiologic); cardiovascular and all-cause mortality (prognostic)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis of prospective studies
- Studies and participants, as stated
- >1700 papers screened (etiologic and prognostic studies)
meta-analysis · 2015
Shor et al. (2015) — Social contact frequency and all-cause mortality: a meta-analysis and meta-regression.
- What it measured
- All-cause mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Meta-analysis and meta-regression
- Studies and participants, as stated
- 187 risk estimates from 91 publications; ~400,000 persons
meta-analysis · 2025
Levis et al. (2025) — Loneliness, Social Isolation, and Social Support and the Development of Type II Diabetes: A Systematic Review and Meta-Analysis
- What it measured
- Incident type 2 diabetes mellitus (T2DM) risk
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis (random-effects)
- Studies and participants, as stated
- 18 studies
Key sources (17)
Every source below is shown with its study design and links to the original study. This is the audit trail.
other designSocial disconnection and mortality: new evidence for old truths.
meta-analysisLoneliness, social network size and mortality in older adults: a meta-analysis
meta-analysisLoneliness, social isolation, and living alone: a comprehensive systematic review, meta-analysis, and meta-regression of mortality risks in older adults
meta-analysisThe impact of social relationships on the risk of stroke and post-stroke mortality: a systematic review and meta-analysis
meta-analysisA meta-analysis of the association between loneliness and all-cause mortality in older adults.
meta-analysisAssociation of loneliness with all-cause mortality: A meta-analysis
systematic reviewAn overview of systematic reviews on the public health consequences of social isolation and loneliness.
meta-analysisMeta-analysis: Social Isolation, Loneliness Tied to Higher Mortality.
meta-analysisA systematic review and meta-analysis of 90 cohort studies of social isolation, loneliness and mortality
meta-analysisSocial isolation as a risk factor for all-cause mortality: Systematic review and meta-analysis of cohort studies
meta-analysisAssociations between dimensions of the social environment and cardiometabolic health outcomes: a systematic review and meta-analysis
systematic reviewPotential impact of physical distancing on physical and mental health: a rapid narrative umbrella review of meta-analyses on the link between social connection and health
meta-analysisLoneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies
meta-analysisInfluences of socioeconomic status, social network, and competence on subjective well-being in later life: a meta-analysis.
meta-analysisLack of Social Support in the Etiology and the Prognosis of Coronary Heart Disease: A Systematic Review and Meta-Analysis
meta-analysisSocial contact frequency and all-cause mortality: a meta-analysis and meta-regression.
meta-analysisLoneliness, Social Isolation, and Social Support and the Development of Type II Diabetes: A Systematic Review and Meta-Analysis
Explore all 367 studies in Social →
The full evidence base this focus area draws on, every study with its design and DOI.What it is for
Deepen my closest relationshipsFeel more connected to peopleUnderstand myself better