Nutrition and health

Objectives:
Lifestyle interventions are an important and viable approach for preventing cognitive deficits. However, the results of studies on alcohol, coffee and tea consumption in relation to cognitive decline have been divergent, likely due to confounds from dose-response effects. Therefore, this review article (meta-analysis) has been conducted.

Does alcohol, coffee or tea consumption reduce the risk of cognitive deficits (such as dementia or Alzheimer's disease)?

Study design:
This review article included 29 prospective cohort studies from America, Japan, China and some European countries (131,777 participants for alcohol, 333,843 participants for coffee and 20,411 participants for tea).

The NOS score was 8.

Results and conclusions:
The investigators found dose-response relationships showed that compared to non-drinkers, low consumption (11 g/day) of alcohol significantly reduced the risk of cognitive deficits or only dementias, but there was no significant effect of heavier drinking (>11 g/day).

The investigators found dose-response relationships showed that compared to non-drinkers, low consumption of coffee significantly reduced the risk of any cognitive deficit (2.8 cups/day) or dementia (2.3 cups/day).
However, coffee drinking was not a significant protective factor for cognitive deficits in groups of average age 60 years.

The investigators found dose-response relationships showed that compared to non-drinkers, every cup of green tea per day significantly reduced risk of cognitive deficits with 6% [relative risk = 0.94, 95% CI = 0.92 to 0.97].  

The investigators concluded that light consumption of alcohol (11 g/day) and coffee (2.8 cups/day) reduces risk of cognitive deficits. Cognitive benefits of green tea consumption increases with the daily consumption.

Original title:
Alcohol, coffee and tea intake and the risk of cognitive deficits: a dose-response meta-analysis by Ran LS, Liu WH, […], Wang W.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8061189/

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Objectives:
Does tart cherry (TC) supplementation improve recovery following strenuous exercise?

Study design:
This review article included 14 studies.

Results and conclusions:
The investigators found tart cherry supplementation had a small significant beneficial effect in reducing muscle soreness [effect size (ES) = -0.44, 95% CI = -0.87 to -0.02].

The investigators found a moderate significant beneficial effect was observed for recovery of muscular strength [ES = -0.78, 95% CI = -1.11 to -0.46] for tart cherry supplementation.

The investigators found a moderate significant effect was observed for muscular power [ES = -0.53, 95% CI = -0.77 to -0.29] for tart cherry supplementation.
A further subgroup analysis on this variable indicated a large significant effect of tart cherry supplementation on recovery of jump height [ES = -0.82, 95% CI = -1.18 to -0.45] and a small significant effect of tart cherry supplementation on sprint time [ES = -0.32, 95% CI = -0.60 to -0.04]. 

The investigators found a small significant effect was observed for both C-reactive protein [ES = -0.46, 95% CI = -0.93 to -0.00] and Interleukin-6 [ES = -0.35, 95% CI = -0.68 to -0.02] for tart cherry supplementation.

The investigators found no significant effects were observed for creatine kinase and tumor necrosis factor alpha (TNF-α) for tart cherry supplementation. 

The investigators concluded that tart cherry supplementation improves aspects of recovery from strenuous exercise.

Original title:
Tart Cherry Supplementation and Recovery From Strenuous Exercise: A Systematic Review and Meta-Analysis by Hill JA, Keane KM, […], Howatson G.

Link:
https://pubmed.ncbi.nlm.nih.gov/33440334/

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Objectives:
Do magnesium intakes reduce risk of all-cause, cancer and cardiovascular disease (CVD) mortality?

Study design:
This review article included 19 prospective cohort studies with a total of 1,168,756 participants (52,378 deaths from all causes (all-cause mortality), 23,478 from cardiovascular disease (CVD) and 11,408 from cancer).
The follow-up period was 3.5 to 32 years.

Results and conclusions:
The investigators found dietary magnesium intake was significantly associated with a lower risk of 13% for all-cause mortality [pooled effect size (ES) = 0.87, 95% CI = 0.79 to 0.97, p = 0.009, I2 = 70.7%, p 0.001].

The investigators found dietary magnesium intake was significantly associated with a lower risk of 20% for cancer mortality [pooled ES = 0.80, 95% CI = 0.67 to 0.97, p = 0.023, I2 = 55.7%, p = 0.027].

The investigators found for supplemental and total magnesium intakes, no significant associations with risks of all-cause, cardiovascular disease and cancer mortality.

The investigators found, however, linear dose-response meta-analysis indicated that each additional intake of 100 mg/d of dietary magnesium was significantly associated with a 6% and 5% reduced risk of all-cause and cancer mortality, respectively.

The investigators concluded that higher intake of dietary magnesium (at least 100 mg/d of dietary magnesium) is associated with a reduced risk of all-cause and cancer mortality, but not cardiovascular disease mortality. Supplemental and total magnesium intakes are not associated with the risk of all-cause, cardiovascular disease and cancer mortality. These findings indicate that consumption of magnesium from dietary sources may be beneficial in reducing all-cause and cancer mortality and thus have practical importance for public health.  

Original title:
Total, Dietary, and Supplemental Magnesium Intakes and Risk of All-Cause, Cardiovascular, and Cancer Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies by Bagheri A, Naghshi S, […], Esmaillzadeh A.

Link:
https://pubmed.ncbi.nlm.nih.gov/33684200/

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Objectives:
Previous population studies on the associations between dietary fatty acids (FAs), plasma FAs levels and the risk of age-related macular degeneration (AMD) have yielded inconclusive results. Therefore, this review article (meta-analysis) has been conducted.

Do higher dietary fatty acids (EPA and DHA) intakes or higher plasma fatty acids levels reduce risk of age-related macular degeneration?

Study design:
This review article included 11 prospective cohort studies with 167,581 participants. During the follow-up periods (ranging from 3 to 28 years), 6,318 cases of age-related macular degeneration were recorded.

Results and conclusions:
The investigators found that each 1 g/day increment of dietary intake of docosahexaenoic acid (DHA) and eicosatetraenoic acid (EPA) combined significantly reduced risk of early age-related macular degeneration with 33% [RR = 0.67, 95% CI = 0.51 to 0.88].
Significantly means that there is an association with a 95% confidence.

The investigators found that each 1 g/day increment of dietary intake of docosahexaenoic acid (DHA) significantly reduced risk of early age-related macular degeneration with 50% [RR = 0.50, 95% CI = 0.32 to 0.78].
Significantly means it can be said with a 95% confidence that each 1 g/day increment of dietary intake of docosahexaenoic acid (DHA) really reduces risk of early age-related macular degeneration with 50%.

The investigators found that each 1 g/day increment of dietary intake of eicosatetraenoic acid (EPA) significantly reduced risk of early age-related macular degeneration with 60% [RR = 0.40, 95% CI = 0.18 to 0.87].
Significantly because RR of 1 was not found in the 95% CI of 0.18 to 0.87. RR of 1 means no risk/association.

The investigators found that higher plasma docosahexaenoic acid (DHA) levels significantly reduced risk of advanced age-related macular degeneration with 28% [RR = 0.72, 95% CI = 0.55 to 0.95].

The investigators found that higher plasma eicosatetraenoic acid (EPA) levels significantly reduced risk of advanced age-related macular degeneration with 43% [RR = 0.57, 95% CI = 0.40 to 0.81].

The investigators concluded that 1 g/day of dietary intake DHA and 1 g/day of dietary intake EPA and higher plasma DHA and EPA levels are associated with a reduced risk of age-related macular degeneration.

Original title:
Dietary fatty acid intake, plasma fatty acid levels, and the risk of age-related macular degeneration (AMD): a dose-response meta-analysis of prospective cohort studies by Zhong Y, Wang K, [...], Yao K.

Link:
https://pubmed.ncbi.nlm.nih.gov/33469697/

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A high plasma EPA and DHA content can be obtained by eating a lot of oily fish and/or by taking EPA and DHA supplements (fish oil supplements).
Oily fish contains more EPA and DHA than non-oily fish.

Early age-related macular degeneration: most people do not experience adverse symptoms or vision loss in the early stage of age-related macular degeneration, but night vision problems are often reported. Though no pigmentary abnormalities are apparent upon examination, medium-sized drusen (>63 μm and ≤125 μm) are present.

Objectives:
Previous studies on the association between alcohol intake and risk of fracture have reached conflicting findings. Therefore, this review article has been conducted.

Does alcohol consumption increase risk of fractures?

Study design:
This review article included 38 prospective cohort studies with a total sample size of 5,053,117 participants and 169,560 cases of fracture.

Results and conclusions:
The investigators found in a random-effects meta-analysis, that alcohol consumption significantly increased risk of total fractures with 35% [RR = 1.35, 95% CI = 1.01 to 1.81] and any fractures with 24% [RR= 1.24, 95% CI = 1.11 to 1.38].
Significant because RR of 1 was not found in the 95% CI of 1.01 to 1.81. RR of 1 means no risk/association.

The investigators found, however, no significant association between alcohol intake and risk of hip fractures [RR = 1.19, 95% CI = 0.96 to 1.48], osteoporotic fractures [RR = 2.01, 95% CI = 0.76 to 5.34], vertebral fractures [RR = 0.98, 95% CI = 0.68 to 1.40] and wrist fractures [RR = 0.99, 95% CI = 0.85 to 1.16].
No significant because RR of 1 was found in the 95% CI of 0.85 to 1.06. RR of 1 means no risk/association.

The investigators concluded that alcohol consumption is positively associated with risk of total fractures and any fractures.

Original title:
A systematic review and meta-analysis of prospective cohort studies on the association between alcohol intake and risk of fracture by Asoudeh F, Salari-Moghaddam A, […], Esmaillzadeh A.

Link:
https://pubmed.ncbi.nlm.nih.gov/33596741/

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Objectives:
Visceral adipose tissue (VAT) are deleterious fat deposits in the human body and can be effectively reduced by exercise intervention. Despite well-established exercise prescriptions are available, the effective dosage of exercise for reducing VAT requires verification. Therefore, this review article has been conducted.

What is the most effective exercise dosage (modality, intensity, duration and amount) for decreasing visceral adipose tissue (VAT)?

Study design:
This review article included 32 RCTs with a total of 1,900 participants.

Results and conclusions:
The investigators found that 30-60 min of high-intensity interval training, 3 times per week for 12 to 16 weeks [SMD = -0.39, 95% CI = -0.60 to -0.18] and 30-60 min of aerobic exercise of at least moderate intensity, 3 times per week for 12 to 16 weeks [SMD = -0.26, 95% CI = -0.38 to -0.13] were beneficial for reducing visceral adipose tissue.

The investigators found, by contrast, resistance exercise, aerobic exercise combined with resistance exercise and sprint interval training had no significant effects on reducing visceral adipose tissue.

The investigators found no difference in visceral adipose tissue reduction was observed between exercising more or less than 150 minutes per week.

The investigators found meta-regression revealed that the effect of visceral adipose tissue reduction was not significantly influenced by an increase in the duration of or amount of exercise in an exercise program.

The investigators concluded that 30-60 min of high-intensity interval training, 3 times per week for 12 to 16 weeks and 30-60 min of aerobic exercise of at least moderate intensity, 3 times per week for 12 to 16 weeks causally reduce visceral adipose tissue.

Original title:
Effect of exercise intervention dosage on reducing visceral adipose tissue: a systematic review and network meta-analysis of randomized controlled trials by Chang YH, Yang HY and Shun SC.

Link:
https://pubmed.ncbi.nlm.nih.gov/33558643/

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A causal relationship can be found in RCTs.

High intensity interval trainings are:
-using a stationary bike, pedal as hard and fast as possible for 30 seconds.
-after jogging to warm up, sprint as fast as you can for 15 seconds.
-perform squat jumps as quickly as possible for 30 to 90 seconds.

Objectives:
Recent evidence suggests that diet can modify the risk of future cognitive impairment and dementia. A biologically plausible rationale and initial clinical data indicate that the antioxidant activities of dietary carotenoids may assist the preservation of cognitive function. Therefore, this review article has been conducted.

Does carotenoid supplementation improve cognitive performance among healthy adults?

Study design:
This review article included 9 RCTs, involving 2,228 subjects in the treated group (group with carotenoid supplementation) and 2,174 subjects in control group (group without carotenoid supplementation).
The age of all participants varied from 45 to 78 years.
The majority of clinical trials assessed the effect of xanthophylls such as lutein, zeaxanthin, and astaxanthin, whereas only 1 study determined the effects of β-carotene.
The duration of carotenoid supplementation ranged from 2 weeks to 12 months.
The dosage of carotenoids administered in the studies ranged from 0.5 mg/d to 50 mg/d.
There was no evidence of publication bias.

Results and conclusions:
The investigators found results of the pooled meta-analysis showed a significant effect of carotenoid intervention on cognitive outcomes [Hedge's g = 0.14, 95% CI = 0.08 to 0.20, p 0.0001, I2 = 0.00%].
The sensitivity analysis did not change the overall findings obtained from the primary analysis.

The investigators concluded that these results highlight the potential role of carotenoids (0.5 mg/d to 50 mg/d) in the protection of mental functions even in subjects (healthy participants aged 45-78 years) without cognitive impairment. This is particularly important because the population is aging and preservation of cognitive function is crucial for individual autonomy and quality of life, even in non-demented subjects. Further well-powered and long-term trials are required to determine treatment duration, type of carotenoid and optimal dosage.

Original title:
Carotenoids and Cognitive Outcomes: A Meta-Analysis of Randomized Intervention Trials by Davinelli S, Ali S, […], Corbi G.

Link:
https://www.mdpi.com/2076-3921/10/2/223/htm

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Objectives:
Increasing macular pigment optical density (MPOD) as a result of increased macular concentration of lutein and zeaxanthin may reduce the risk of age-related macular degeneration (AMD). Therefore, this review article has been conducted.

Have daily egg consumption beneficial effects on macular pigment optical density and serum lutein levels?

Study design:
This review article included 5 RCTs with a total of 296 participants.
There was no heterogeneity between studies.

Results and conclusions:
The investigators found that egg consumption significantly increased macular pigment optical density [WMD = +0.037, 95% CI = 0.004 to 0.069, p = 0.027] and serum lutein levels [WMD = +0.150 μmol/L, 95% CI = 0.037 to 0.263, p = 0.009].

The investigators found subgroup analyses showed that egg consumption had a larger effect on macular pigment optical density in studies with a parallel design and increased serum lutein levels to a greater extent in a healthy population.

The investigators concluded daily egg consumption have beneficial effects on macular pigment optical density and serum lutein level is inversely associated with reduced age-related macular degeneration progression. Further clinical trials are required to confirm the results of this review article.

Original title:
A positive effect of egg consumption on macular pigment and healthy vision: a systematic review and meta-analysis of clinical trials by Sikaroudi MK, Saraf-Bank S, […], Soltani S.

Link:
https://pubmed.ncbi.nlm.nih.gov/33491232/

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Objectives:
Does a high dietary intake of β-cryptoxanthin reduce the risk of osteoporosis and hip fracture?

Study design:
This review article included 7 cohort studies, 4 case-control studies and 4 cross-sectional studies with a total of 100,496 individuals.
The methodological qualities of all studies were rated as “fair” to “good”.
The number of populations in each study ranged from 59 to 25,566.

Results and conclusions:
The investigators found that a high dietary intake of β-cryptoxanthin significantly reduced risk of osteoporosis with 24% [OR = 0.76, 95% CI = 0.66 to 0.88, p = 0.0002, I2 = 36%, p = 0.11].

The investigators found in subgroup analysis that a high dietary intake of β-cryptoxanthin significantly reduced risk of osteoporosis with 28% [OR = 0.72, 95% CI = 0.58 to 0.91, p = 0.005, I2 = 59%] among women.

The investigators found in subgroup analysis that a high dietary intake of β-cryptoxanthin significantly reduced risk of osteoporosis with 20% [OR = 0.80, 95% CI = 0.65 to 1.00, p = 0.005, I2 = 11%] among men.

The investigators found that a high dietary intake of β-cryptoxanthin significantly reduced risk of hip fracture with 28% [OR = 0.72, 95% CI = 0.60 to 0.87, p = 0.0008, I2 = 55%].

The investigators found in subgroup analysis that a high dietary intake of β-cryptoxanthin significantly reduced risk of hip fracture with 29% [OR = 0.71, 95% CI = 0.54 to 0.94, p = 0.02, I2 = 71%] among women. 

The investigators concluded that a high dietary intake of β-cryptoxanthin reduces the risk of osteoporosis and hip fracture. Further longitudinal studies are needed to validate the causality of current findings.

Original title:
Effects of β-Cryptoxanthin on Improvement in Osteoporosis Risk: A Systematic Review and Meta-Analysis of Observational Studies by Kim SJ, Anh NH, […], Kwon SW.

Link:
https://www.mdpi.com/2304-8158/10/2/296/htm

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Objectives:
Is there a difference between high-load (≥70 of 1RM) and low-load (70 of 1RM) resistance training (RT) on femoral neck and lumbar spine bone mineral density (BMD) in middle-aged and older people?

Study design:
This review article included 6 RCTs.

Results and conclusions:
The investigators found the meta-analysis revealed no difference in femoral neck bone mineral density [MD = 0.00 g/cm², 95% CI = -0.01 to 0.01, p = 0.63, I2 = 47%, p = 0.07] and lumbar spine bone mineral density [MD = 0.01 g/cm², 95% CI = -0.00 to 0.02, p = 0.12, I2 = 59%, p = 0.02] between high-load (≥70 of 1RM) resistance training group and low-load (70 of 1RM) resistance training group. 

The investigators found subgroup analysis revealed a significant effect of high-load resistance training on femoral neck bone mineral density when participants presented normal bone mineral density values [MD = 0.01 g/cm², 95% CI = 0.00 to 0.02, p = 0.04] and on interventions lasting up to 6 months [MD = 0.01 g/cm², 95% CI = 0.00 to 0.02, p = 0.03].

The investigators concluded both high-load (≥70 of 1RM) and low-load (70 of 1RM) resistance training (RT) have similar effects on femoral neck and lumbar spine bone mineral density (BMD) in middle-aged and older people.

Original title:
High and Low-Load Resistance Training Produce Similar Effects on Bone Mineral Density of Middle-Aged and Older People: A Systematic Review With Meta-Analysis of Randomized Clinical Trials by Souza D, Barbalho M, […], Gentil P.

Link:
https://www.sciencedirect.com/science/article/abs/pii/S0531556520303211?via%3Dihub

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Objectives:
Do omega-3 fatty acid supplements (EPA and DHA) improve sarcopenia-related performances among the elderly?

Study design:
This review article included 10 RCTs with 552 participants.
The number of study participants ranged from 24 to 126 and the durations of the interventions spanned 10 to 24 weeks.
The doses ranged from 0.16 to 2.6 g/day of EPA and from 0 to 1.8 g/day of DHA.
The mean ages of the participants across the RCTs ranged from 63 to 75 years old.

Results and conclusions:
The investigators found in subgroup analyses that omega-3 fatty acid supplements (EPA and DHA) at more than 2 g/day significantly increased muscle mass among the elderly [SMD = 0.67 kg, 95% CI = 0.16 to 1.18, p 0.05].

The investigators found in subgroup analyses that omega-3 fatty acid supplements (EPA and DHA) during more than 6 months significantly improved walking speed among the elderly [SMD = 1.78 m/sec, 95% CI = 1.38 to 2.17, p 0.05].

The investigators concluded that taking at least 2 grams of omega-3 supplements (EPA and DHA) per day increases muscle mass among the elderly, while taking omega-3 supplements for at least 6 months increases walking speed among the elderly.

Original title:
Effects of Omega-3 Fatty Acids on Muscle Mass, Muscle Strength and Muscle Performance among the Elderly: A Meta-Analysis by Huang YH, Chiu WC, […], Wang YH.

Link:
https://www.mdpi.com/2072-6643/12/12/3739/htm

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EPA and DHA are present in fish.
 

Objectives:
Does calcium combined with vitamin D supplementation reduce risk of osteoporosis in postmenopausal women?

Study design:
This review article included 10 RCTs.

Results and conclusions:
The investigators found calcium combined with vitamin D supplementation significantly increased total bone mineral density [SMD = 0.537, 95% CI = 0.227 to 0.847] in postmenopausal women.

The investigators found calcium combined with vitamin D supplementation significantly increased lumbar spine bone mineral density [SMD = 0.233, 95% CI = 0.073 to 0.392, p 0.001] in postmenopausal women.

The investigators found calcium combined with vitamin D supplementation significantly increased arms bone mineral density [SMD = 0.464, 95% CI = 0.186 to 0.741] in postmenopausal women.

The investigators found calcium combined with vitamin D supplementation significantly increased femoral neck bone mineral density [SMD = 0.187, 95% CI = 0.010 to 0.364] in postmenopausal women.

The investigators found calcium combined with vitamin D supplementation significantly reduced risk of hip fracture with 13.6% [RR = 0.864, 95% CI = 0.763 to 0.979] in postmenopausal women.

The investigators found in subgroup analysis that calcium combined with 400 IU/d (10 mcg/d) vitamin D supplementation significantly increased femoral neck bone mineral density [SMD = 0.335, 95% CI = 0.113 to 0.558] in postmenopausal women.

The investigators found in subgroup analysis that dairy products fortified with calcium and vitamin D significantly increased total bone mineral density [SMD = 0.784, 95% CI = 0.322 to 1.247] in postmenopausal women.

The investigators found in subgroup analysis that dairy products fortified with calcium and vitamin D significantly increased lumbar spine bone mineral density [SMD = 0.320, 95% CI = 0.146 to 0.494] in postmenopausal women.

The investigators concluded that dairy products fortified with calcium and vitamin D have a favourable effect on bone mineral density. Furthermore, calcium combined with vitamin D supplementation could prevent osteoporosis hip fracture in postmenopausal women.

Original title:
Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials by Liu C, Kuang X […], Li D.

Link:
https://pubmed.ncbi.nlm.nih.gov/33237064/

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Objectives:
Isoflavones have a structure similar to 17β-estradiol, so they may be useful to postmenopausal women in preventing bone loss related to estrogen deficiency. Therefore, this review article has been conducted.

Do isoflavone supplements increase bone mineral density (BMD) in postmenopausal women?

Study design:
This review article included 63 RCTs, involving 6,427 postmenopausal women.

Isoflavone interventions were generally safe and well tolerated.

Results and conclusions:
The investigators found statistically significant differences in bone mineral density at the last follow-up visit between the two groups (isoflavones vs. control) at the lumbar spine [MD = 21.34 mg/cm², 95% CI = 8.21 to 34.47 mg/cm², p = 0.001], the femoral neck [MD = 28.88 mg/cm², 95% CI = 15.05 to 42.71 mg/cm², p 0.0001] and the distal radius [MD = 19.27 mg/cm², 95% CI = 5.65 to 32.89 mg/cm², p = 0.006].
This improved bone mineral density was found for genistein 54 mg/day and ipriflavone (a synthetic isoflavone) 600 mg/day.

The investigators concluded isoflavone interventions, genistein (54 mg/day) and ipriflavone (600 mg/day) in particular, have beneficial effects on bone mineral density outcomes and are safe in postmenopausal women. They may be considered as a complementary or alternative option in the prevention and treatment of menopause-related osteoporosis.

Original title:
Effects of Isoflavone Interventions on Bone Mineral Density in Postmenopausal Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Sansai K, Takuathung MN, [...], Koonrungsesomboon N.

Link:
https://pubmed.ncbi.nlm.nih.gov/32524173/

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Objectives:
Has oral supplementation of vitamin B (vitamins B1, B6, B12 and folic acid alone or combined) preventive effect on cognitive decline in cognitively unimpaired individuals?

Study design:
This review article included 20 RCTs, ranging from 23 to 2,919 participants per study, with a total of 12,697 participants.
8 of these 20 RCTs were deemed appropriate for the meta-analysis.

Results and conclusions:
The investigators found meta-analysis did not yield a significant overall effect of supplementation with vitamin B on cognitive function [SMD = 0.02, 95% CI = -0.034 to 0.08]. A sensitivity analysis focusing on specific risk factors did not alter this result.
Some studies reported isolated significant effects of the intervention on secondary outcomes. However, these findings were outnumbered by the number of cognitive tests that did not yield significant effects.

The investigators concluded there is no overall evidence that oral vitamin B supplementation prevent cognitive decline in cognitively unimpaired individuals. The results of this review do not provide evidence that population groups with certain risk factors would profit more from the intervention than others.

Original title:
Vitamin B-Can It Prevent Cognitive Decline? A Systematic Review and Meta-Analysis by Behrens A, Graessel E, [...], Donath C.

Link:
https://systematicreviewsjournal.biomedcentral.com/articles/10.1186/s13643-020-01378-7

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Objectives:
Nitric oxide related ergogenic aids such as arginine (Arg) have shown to impact positively on sport performance through several physiological and metabolic mechanisms. However, research results have shown to be controversial. Therefore, this review article has been conducted.

Do both acute and chronic arginine supplementation increase aerobic (≤VO2max) and anaerobic (>VO2max) performance?

Study design:
This review article included 15 RCTs with 386 males and 8 females.

Arginine supplementation was ingested by participants in both acute and chronic protocols.
Acute arginine protocol was 0.15 g/kg (≈10-11 g) ingested between 60-90 minutes before physical exercises.

Chronic arginine protocol was 1.5-2 g/day during 4-7 weeks or 10-12 g/day during 8 weeks.

Random effects model and pooled standardized mean differences (SMD) were used according to Hedges’ g.

Egger’s analyses did not find publication bias in anaerobic performance [z = 0.786, p = 0.432]. However, funnel plot showed publication bias in aerobic performance data [z = 2.873, p 0.05].

Results and conclusions:
The investigators found both acute and chronic arginine supplementation significantly improved anaerobic performance [SMD = 0.24, 95% CI = 0.05 to 0.43, p = 0.01, I2 = 0%, p = 0.85].

The investigators found both acute and chronic arginine supplementation significantly improved aerobic performance [SMD = 0.84, 95% CI = 0.12 to 1.56, p = 0.02, I2 = 89%, p 0.001].

The investigators concluded both acute and chronic arginine supplementation improve (anaerobic/aerobic) performance.

Original title:
Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis by Viribay A, Burgos J, […], Mielgo-Ayuso J.

Link:
https://www.mdpi.com/2072-6643/12/5/1300/htm

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Objectives:
Does protein supplementation yield beneficial effects on body composition and muscle function (strength and synthesis) in healthy adults, with an emphasis on the timing of protein intake?

Study design:
This review article included 65 RCTs with 2,907 participants (1,514 men and 1,380 women, 13 unknown sex). 26, 8 and 24 studies were used for meta-analysis on lean body mass, handgrip strength and leg press strength, respectively.

Results and conclusions:
The investigators found protein supplementation was effective in improving lean body mass (LBM) in adults [MD = 0.62 kg, 95% CI = 0.36 to 0.88] and older adults [MD = 0.46 kg, 95% CI = 0.23 to 0.70].
Sensitivity analyses removing studies without exercise training had no impact on the outcome.

The investigators found no association between protein supplementation and handgrip strength [older adults: MD = 0.26 kg, 95% CI = -0.51 to 1.04] and leg press strength [adults: MD = 5.80 kg, 95% CI = -0.33 to 11.93 and older adults: MD = 1.97 kg, 95% CI = -2.78 to 6.72].
Sensitivity analyses removing studies without exercise training had no impact on the outcome.

The investigators found data regarding muscle synthesis were scarce and inconclusive.

The investigators found subgroup analyses showed no beneficial effect of a specific timing of protein intake on lean body mass, handgrip strength and leg press strength.

The investigators concluded there is a positive impact of protein supplementation on lean body mass of healthy adults and older adults, independently of intake timing.

Original title:
The Role of Protein Intake and its Timing on Body Composition and Muscle Function in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Wirth J, Hillesheim E and Brennan L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32232404

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The more lean body mass a person has, the higher their resting metabolic rate. Resting metabolic rate is the total number of calories burned when your body is completely at rest. Resting metabolic rate supports breathing, circulating blood, organ functions and basic neurological functions.

Objectives:
Previous studies did not draw a consistent conclusion about the effects of vitamin K combined with vitamin D on human skeletal quality. Therefore, this review article has been conducted.

Does vitamin K combined with vitamin D supplementation increase bone mineral density (BMD)?

Study design:
This review article included 8 RCTs with a total of 971 participants.

Results and conclusions:
The investigators found vitamin K combined with vitamin D supplementation significantly increased total bone mineral density (BMD) [pooled effect size = 0.316, 95% CI = 0.031 to 0.601].

The investigators found vitamin K combined with vitamin D supplementation significantly decreased levels of undercarboxylated osteocalcin [effect size = -0.945, 95% CI = -1.113 to -0.778].

The investigators found simultaneously, subgroup analysis showed that K2 or vitamin K (not specified) supplement less than 500 μg/d, when combined with vitamin D significantly increased total bone mineral density compared with the control group fed a normal diet or the group with no treatment [effect size = 0.479, 95% CI = 0.101 to 0.858 and effect size = 0.570, 95% CI = 0.196 to 0.945, respectively).

The investigators concluded the combination of vitamin K and D supplement increases the total bone mineral density (BMD) and decreases levels of undercarboxylated osteocalcin and a more favorable effect is expected when less than 500 μg/d vitamin K2 is used.

Original title:
The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials by Kuang X, Liu C, […], Li D.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32219282

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Undercarboxylated osteocalcin represents inadequately carboxylated osteocalcin and this fraction increases with vitamin K insufficiency.

Objectives:
Is there a causal relationship between dietary intake of dairy products and a positive effect on bone mineral density (BMD) in healthy postmenopausal women?

Study design:
This review article included 6 RCTs with a total of 618 participants. Milk was the main dairy product used in the trials.

Results and conclusions:
The investigators found there was a significant association between dairy product consumption and bone mineral density of the lumbar spine [SMD = 0.21, 95% CI = 0.05 to 0.37, p = 0.009], femoral neck [SMD = 0.36, 95% CI = 0.19 to 0.53, p  0.001], total hip [SMD = 0.37, 95% CI = 0.20 to 0.55, p  0.001] and total body [SMD = 0.58, 95% CI = 0.39 to 0.77, p  0.001].

The investigators found subgroup analysis showed a positive effect of dairy product consumption on the bone mineral density of the total hip starting from 12 months and the femoral neck starting from 18 months. There was also a positive association with the bone mineral density in the 4 sites in people living in low-calcium intake countries.

The investigators concluded that there is a causal relationship between dietary intake of dairy products, particularly milk during at least 12 months and a positive effect on bone mineral density (BMD) in healthy postmenopausal women. Therefore, dairy product consumption should be considered an effective public health measure to prevent osteoporosis in postmenopausal women.

Original title:
Effects of dairy products on bone mineral density in healthy postmenopausal women: a systematic review and meta-analysis of randomized controlled trials by Shi Y, Zhan Y, [...], Jiang Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32185512

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Menopause is the point when a woman no longer has menstrual periods for at least 12 months. Postmenopause is the stage after menopause.

Objectives:
Does a high LDL cholesterol level (bad cholesterol) increase risk of Alzheimer's disease (AD)?

Study design:
This review article included 26 case-control studies involving 7,033 participants (2,266 Alzheimer's disease patients and 4,767 non-dementia controls).

There was no significant evidence of publication bias according to the results of Egger's test [p = 0.084].

Results and conclusions:
The investigators found results from the meta-analysis of 26 studies revealed higher levels of LDL cholesterol (>121 mg/dL) in Alzheimer's disease than that of non-dementia controls [SMD = 0.35, 95% CI = 0.12 to 0.58, p 0.01], which was consistent with the results of the fixed-effect model [SMD = 0.16, 95% CI = 0.10 to 0.22, p 0.01].
Sensitivity analyses showed that no single study exerted substantial influence on the pooled effect size after sequentially omitting a study.

The investigators found subgroup analysis of age showed LDL cholesterol levels in Alzheimer's disease patients aged 60-70 were higher than that of non-dementia [60 ≤ age 70: SMD = 0.80, 95% CI = 0.23 to 1.37, p 0.01].  

The investigators concluded that elevated concentration of LDL cholesterol (>121 mg/dL) is a risk factor for Alzheimer's disease. This strong association is significant in patients with Alzheimer's disease aged 60-70 years, but vanishes with increasing age. This review article provides a promising strategy for reducing the risk of Alzheimer's disease in patients with hyperlipidemia, which may be achieved by regulating LDL cholesterol concentration between 103.9 and 121 mg/dL with statins. Prospective studies that exclude potential confounders, more scientific design and adequate long-term follow-up are needed to validate this hypothesis.

Original title:
Low-Density Lipoprotein Cholesterol and Alzheimer's Disease: A Systematic Review and Meta-Analysis by Zhou Z, Liang Y, […], Zhao M.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002548/

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Objectives:
Which types of exercise training (whole body vibration training, aerobic training, strength training and combined training) increase lumbar spine and femoral neck bone mineral density (BMD) in older postmenopausal women (PMW)?

Study design:
This review article included 16 RCTs with 1,624 subjects.

Results and conclusions:
The investigators found no significant change in lumbar spine bone mineral density following exercise training [MD = 0.01 g/cm², 95% CI = -0.01 to 0.02].

The investigators found no significant change in femoral neck bone mineral density following exercise training [MD = 0.00 g/cm², 95% CI = -0.01 to 0.01].

The investigators found, however, subgroup analysis by type of exercise training revealed that lumbar spine bone mineral density [MD = 0.01, 95% CI = 0.00 to 0.02] raised significantly when whole-body vibration (WBV) was employed as intervention compared with RCTs that utilized aerobic [MD = -0.01, 95% CI = -0.02 to -0.01], resistance [MD = 0.01, 95% CI = -0.04 to 0.06] or combined training [MD = 0.03, 95% CI = -0.01 to 0.08].

The investigators found, on the other hand, lumbar spine bone mineral density [MD = - 0.01, 95% CI = -0.02 to -0.01] reduced significantly when aerobic exercise training was used as intervention compared with RCTs that utilized resistance training, combined training or whole-body vibration. 

The investigators concluded whole-body vibration is an effective method to improve lumbar spine bone mineral density in older postmenopausal women.

Original title:
The Impact of Different Modes of Exercise Training on Bone Mineral Density in Older Postmenopausal Women: A Systematic Review and Meta-analysis Research by Mohammad Rahimi GR, Smart NA, […], Mohammad Rahimi N.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32055889

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Objectives:
Several epidemiological studies have been performed to evaluate the association of dietary intake of vitamin C-oriented foods (DIVCF) with risk of fracture and bone mineral density (BMD) loss, but the results remain controversial. Therefore, this review article has been conducted.

Does dietary intake of vitamin C-oriented foods decrease risk of fracture and bone mineral density loss?

Study design:
This review article included 4 cohort studies, 11 case-control studies and 2 cross-sectional studies with a total of 19,484 subjects.

The studies received a quality score of ≥5, indicating that the methodological quality of the studies was generally good.

No evidence of publication bias was found in the evaluation of dietary intake of vitamin C-oriented foods and the risk of hip fracture.

Results and conclusions:
The investigators found that the people with a higher dietary intake of vitamin C-oriented foods had a significantly 34% [RR = 0.66, 95% CI = 0.47 to 0.94, I2 = 79.5%, p = 0.000] lower risk of hip fracture.

The investigators found that the people with a higher dietary intake of vitamin C-oriented foods had a significantly 42% [RR = 0.58, 95% CI = 0.38 to 0.89] lower risk of hip fracture in case-control studies.
However, this reduced risk was not significant in cohort studies [RR = 0.92, 95% CI = 0.59 to 1.44]. 

The investigators found that the people with a higher dietary intake of vitamin C-oriented foods had a significantly 34% [RR = 0.66, 95% CI = 0.48 to 0.92] lower risk of osteoporosis.

The investigators found higher dietary intake of vitamin C-oriented foods was negatively associated with the risk of bone mineral density loss at the lumbar spine [pooled r = 0.15, 95% CI = 0.09 to 0.23] and at the femoral neck [pooled r = 0.20, 95% CI = 0.11 to 0.34].

The investigators concluded that higher dietary intake of vitamin C-oriented foods reduces the risk of hip fracture, osteoporosis and bone mineral density loss, suggesting that people should consume more vitamin C to decrease the risk of hip fracture, osteoporosis and bone mineral density loss, particularly lumbar spine and femoral neck.

Original title:
Can Dietary Intake of Vitamin C-Oriented Foods Reduce the Risk of Osteoporosis, Fracture, and BMD Loss? Systematic Review With Meta-Analyses of Recent Studies by Zeng LF, Luo MH, […], Liu J.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7008177/

Additional information of El Mondo:
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Objectives:
Current evidence on associations between intakes of linoleic acid (LA), the predominant n-6 (ω-6) fatty acid and mortality is inconsistent and has not been summarized by a systematic review and meta-analysis. Therefore, this review article has been conducted.

Does higher linoleic acid intake, assessed by dietary surveys or biomarkers decrease mortality from all causes, cardiovascular disease (CVD) and cancer?

Study design:
This review article included 44 prospective cohort studies with 811,069 participants with dietary intake assessment (170,076 all-cause, 50,786 cardiovascular disease and 59,684 cancer deaths) and 65,411 participants with biomarker measurements (9,758 all-cause, 6,492 cardiovascular disease and 1,719 cancer deaths).

Meta-regressions suggested baseline age and dietary assessment methods as potential sources of heterogeneity for the association between linoleic acid and total mortality.

Results and conclusions:
The investigators found when compared with the lowest categories of dietary linoleic acid intake, that the highest categories of dietary linoleic acid intake significantly reduced total mortality risk with 13% [pooled RR = 0.87, 95% CI = 0.81 to 0.94, I2 = 67.9%].

The investigators found when compared with the lowest categories of dietary linoleic acid intake, that the highest categories of dietary linoleic acid intake significantly reduced cardiovascular disease mortality risk with 13% [pooled RR = 0.87, 95% CI = 0.82 to 0.92, I2 = 3.7%].

The investigators found when compared with the lowest categories of dietary linoleic acid intake, that the highest categories of dietary linoleic acid intake significantly reduced cancer mortality risk with 11% [pooled RR = 0.89, 95% CI = 0.85 to 0.93, I2 = 0%].

The investigators found for each standard deviation increment in linoleic acid concentrations in adipose tissue/blood compartments a significantly reduced total mortality risk of 9% [pooled RR = 0.91, 95% CI = 0.87 to 0.95, I2 = 64.1%].

The investigators found for each standard deviation increment in linoleic acid concentrations in adipose tissue/blood compartments a significantly reduced cardiovascular disease mortality risk of 11% [pooled RR = 0.89, 95% CI = 0.85 to 0.94, I2 = 28.9%].

The investigators found for each standard deviation increment in linoleic acid concentrations in adipose tissue/blood compartments a significantly reduced cancer mortality risk of 9% [pooled RR = 0.91, 95% CI = 0.84 to 0.98, I2 = 26.3%].

The investigators concluded higher linoleic acid intake, assessed by dietary surveys or biomarkers, reduces risk of mortality from all causes, cardiovascular disease and cancer. These data support the potential long-term benefits of PUFA intake in lowering the risk of cardiovascular disease and premature death.

Original title:
Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies by Li J, Guasch-Ferré M, […], Hu FB.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32020162

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Linoleic acid is a PUFA.
 

Objectives:
Alzheimer's disease (AD) is a common type of dementia, which has caused heavy global economic and health burden and the using of statins to treat Alzheimer disease has caused widely debated. Therefore, this review article has been conducted.

Does statin use decrease Alzheimer disease?

Study design:
This review article included a total of 9 RCTs containing 1,489 patients. Of them, 742 patients in the statins group, 747 patients in the control group (group without statins).

There were 9 studies used the MMSE scale, 5 studies used the ADAS-Cog scale, 4 studies used the NPI scale and 6 studies used the ADL scale.

Sensitivity analysis and publication bias test were both negative and the results were relatively reliable and stable.

Results and conclusions:
The investigators found meta-analysis of the 9 studies that reported the MMSE scale scores indicated that there was no significant effect of statins as compared with control group [pooled WMD = 1.09, 95% CI = -0.00 to 2.18, p = 0.05, I2 = 87.9%].

The investigators found meta-analysis of the 5 studies that reported the ADAS-Cog scale scores also indicated that there was no significant effect of statins as compared with control group [pooled WMD = -0.16, 95% CI = -2.67 to 2.36, p = 0.90, I2 = 80.1%].

The investigators found meta-analysis of the 4 studies that reported the NPI scale scores indicated that treatment with statins significantly slowed the rise in the NPI scale scores as compared with control group [pooled WMD = -1.16, 95% CI = -1.88 to -0.44, p = 0.002, I2 = 45.4%].

The investigators found meta-analysis of the 6 studies that reported the ADL scale scores indicated that treatment with statins significantly improve patients' daily living ability [pooled WMD = -4.06, 95% CI = -6.88 to -1.24, p = 0.005, I2 = 86.7%].

The investigators found results of subgroup analysis indicated that the use of statins in the short term (≤ 12 months) associated with the change of the MMSE scale scores [pooled WMD = 1.78, 95% CI = 0.53 to 3.04, p = 0.005, I2 = 79.6%].

The investigators concluded statins used in Alzheimer disease patients have beneficial effects on the scores of MMSE scale in the short term (≤ 12 months) and statins slow the deterioration of neuropsychiatric status and improve activities of daily living ability in Alzheimer disease patients.

Original title:
The efficacy of statins in the treatment of Alzheimer's disease: a meta-analysis of randomized controlled trial by Xuan K, Zhao T, […], Sun Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31930449

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Objectives:
Despite growing evidence for the association between other dietary macronutrients and bone health, limited and inconsistent knowledge is available regarding carbohydrate intake. Therefore, this review article has been conducted.

Does a high carbohydrate intake increase risk of fracture?

Study design:
This review article included observational studies.

Results and conclusions:
The investigators found no association between carbohydrate intake and the risk of fracture in high versus low intake meta-analysis [overall relative risk = 1.24, 95% CI = 0.84 to 1.84, p = 0.27, I2 = 57.7%, p = 0.05].

The investigators found, moreover, there was no relationship between carbohydrate intake and the risk of fracture in both linear [overall RR = 1.00, 95% CI = 0.94 to 1.05, p = 0.88, I2 = 68.1%, p = 0.48] and nonlinear [p non-linearity = 0.14] models.

The investigators concluded high carbohydrate intake does not increase risk of fracture.

Original title:
Dietary carbohydrate intake and risk of bone fracture: a systematic review and meta-analysis of observational studies by Mozaffari H, Daneshzad E and Azadbakht L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31982636

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Objectives:
Which factors increase risk of dementia?

Study design:
This review article included 34 prospective cohort studies, among which 24 were eligible for meta-analysis. A total of 159,594 non-demented adults were enrolled at baseline before 65 years and 13,540 people were diagnosed with dementia after follow-up.

Results and conclusions:
The investigators found obesity significantly increased risk of dementia with 78% [RR = 1.78, 95% CI = 1.31-2.41].

The investigators found diabetes mellitus significantly increased risk of dementia with 69% [RR = 1.69, 95% CI = 1.38-2.07].

The investigators found current smoking significantly increased risk of dementia with 61% [RR = 1.61, 95% CI = 1.32-1.95].

The investigators found hypercholesterolemia significantly increased risk of dementia with 57% [RR = 1.57, 95% CI = 1.19-2.07].
However, the sensitivity analyses showed that the result of hypercholesterolemia was not reliable, which need to be confirmed by more high-quality studies.

The investigators found hypertension significantly increased risk of dementia with 41% [RR = 1.41, 95% CI = 1.23-1.62] for borderline blood pressure.

The investigators found hypertension significantly increased risk of dementia with 72% [RR = 1.72, 95% CI = 1.25-2.37] for high systolic blood pressure.
However, the sensitivity analyses showed that the result of high systolic blood pressure was not reliable, which need to be confirmed by more high-quality studies.

The investigators found hyperhomocysteinemia, psychological stress and heavy drinking were also associated with elevated dementia risk.

The investigators found, in addition, physical exercise, a healthy diet and hormone therapy in middle age were associated with the reduction of dementia risk.

The investigators concluded middle-aged people with obesity or diabetes and current smokers in midlife are at higher risk of developing dementia later in life.

Original title:
Midlife Modifiable Risk Factors for Dementia: A Systematic Review and Meta-analysis of 34 Prospective Cohort Studies by Li XY, Zhang M, [...], Tan L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31902364

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