Table 3.

Human intervention studies on lifestyle/meditation and PBMC telomerase.

Ref	Study design	Predictor	Basal TA	Effects
Lifestyle, diet and nutrition supplementation
(Omish et al., 2008)	24 men with biopsy-diagnosed low-risk prostate cancer	Lifestyle changes, 3 months	TA ↑	TA increased almost 30% during the course of the 3 months intervention. Increases in TA associated with decreases in LDL cholesterol and psychological distress.
(Zhu et al., 2012)	37 overweight African Americans (18 placebo, 19 vitamin D3)	Vitamin D3 2000 IU/day oral, 16 weeks	TA ↑	TA increased by 19.2% from baseline in the vitamin D3 group. No difference in TA in the placebo group.
(Omish et al., 2013)	10 men with biopsy-diagnosed low-risk prostate cancer, 25 controls	Lifestyle changes, 5 years	No difference	No association with lifestyle changes and TA.
(Balcerczyk et al., 2014)	66 healthy women	Supplementation with an antioxidant formula, 12 weeks	TA ↑	TA increased after 12-weeks of supplementation, paralleled by increases in vitamin D level, reductions in oxidative stress levels and increases in the antioxidant potential.
(Pawelczyk et al., 2018)	71 schizophrenia patients	2.2g/day of n-3 PUFA or olive oil placebo, 26 weeks	TA ↑	Higher increases in TA in the intervention group compared to placebo group. Changes in TA were inversely correlated with improvement in depressive symptoms and severity of the illness.
Exercise
(Chilton et al., 2014).	22 healthy males	30 minutes of treadmill running at 80% of peak oxygen uptake	hTERT ↑	hTERT mRNA expression significantly increased from pre- to 60 min post-exercise.
(Zietzer et al., 2016)	26 young healthy participants 14 elderly peripheral artery disease patients	Single session of treadmill running, 30 hrs individual shear rate therapy (ISRT) for 5 weeks	TA ↑ TA ↑	TA increased after a single bout of aerobic exercise. TA increased after a 5-week period of ISRT therapy in elderly patients suffering from peripheral artery disease.
Meditation
(Jacobs et al., 2011)	32 healthy subjects (17 intervention, 25 waitlist controls)	Meditation retreat, 3 months	TA↑	TA activity was significantly higher in intervention group compared to control group, no baseline measured.
(Daubenmier et al., 2012)	47 overweight/obese women (24 intervention, 23 waitlist controls)	Mindfulness intervention on stress-eating, 4 months	TA ↑	18% higher TA increase in intervention group. Changes in TA were negatively correlated to changes in chronic stress, anxiety, dietary restraint, fat intake, cortisol and glucose.
(Ho et al., 2012)	64 chronic fatigue syndrome patients (33 intervention, 31 waitlist controls)	Qigong exercise, 12 weeks	TA ↑	TA increased in the intervention group. TA was higher in the intervention group compared to controls after 4 months.
(Lavretsky et al., 2013)	39 dementia caregivers with mild depressive symptoms	Kirtan Kriya meditation (n = 23) or relaxation music (n = 16), 12 min per day for 8 weeks	TA ↑	TA increased with 43.3% in the meditation group, compared to 3.7% in the relaxation group. Meditation group: correlation between TA and improved mental health score.
(Lengacher et al., 2014)	142 breast cancer survivors (74 intervention, 68 waitlist controls)	Mindfulness-based stress reduction (MBSR), 6 weeks	TA↑	TA increased with 17% over 12 weeks in the MBSR group. No increase in the control group. No difference in TL between both groups.
(Duraimani et al., 2015)	48 hypertensive men and women	Transcendental Meditation + basic health education course (n = 24) or, Extensive health education program (n = 24), 16 weeks	hTERT ↑ hTERC ↑	Both groups showed increased hTERC and hTERT mRNA levels No differences between both groups.
(Epel et al., 2016)	64 non-meditating women, 30 regular meditators	Vacation or meditation retreat, 1 week	TA↑	Baseline TA lower in regular meditators TA increased only in the regular meditation group
(Tolahunase et al., 2017)	96 men and women	Yoga- and meditation-based lifestyle intervention program, 12 weeks	TA↑	TA increased, while levels of 8-OH2dG, ROS, cortisol, and IL-6 decreased after intervention.
(Tolahunase et al., 2018)	58 depressed patients (29 intervention, 29 controls)	Yoga- and meditation-based lifestyle intervention program, 12 weeks	TA ↑	TA increased, while depression severity decreased in intervention compared to control group. In addition, the intervention increased DHEAS and Sirtuin 1 levels, decreased cortisol, IL-6 and DNA damage and balanced oxidative stress.
(Conklin et al., 2018)	28 retreat participants, 34 non-participating controls	Meditation retreat, 3 weeks	No difference	No difference in TA between retreat participants and control group. Pre-assessment TA levels were associated with greater TL increases across both groups. Post-assessment TA levels were negatively correlated with reports of practice diligence and the number of hours of practice time during the retreat.

Abbreviations: DHEAS, Dehydroepiandrosteron sulfate; EEE, exercise energy expenditure; LDL, low-density lipoprotein; 8-OH2dG, 8-Oxo-2'- deoxyguanosine; PUFA, polyunsaturated fatty acid; ROS, Reactive oxygen species; TA, telomerase activity; TL, telomere length.