Nutrition and health

Objectives:
Previous studies have suggested that selenium as a trace element is involved in bone health, but findings related to the specific effect of selenium on bone health remain inconclusive. Therefore, this review article has been conducted.

Do both high dietary selenium intake and high serum selenium levels increase bone density?

Study design:
This review article included 8 cross-sectional studies, 7 case-control studies and 3 prospective cohort studies and 1 RCT with a total of 69,672 subjects.

The number of participants ranged from 60 to 21,939, while the mean age varied from 39.4 to 75.8 years, with mean selenium intake ranging from 41.2 to 154.4 μg/d or mean serum selenium level ranging from 66.7 to 131.1 μg/L.
All the observational studies had a NOS score ≥ 4, namely moderate- to high-quality scores.
There was no publication bias.

Results and conclusions:
The investigators found a significantly positive association between dietary selenium intake [β = 0.04, 95% CI = 0.00 to 0.07, p = 0.029, I2 = 95.91%] as well as serum selenium [β = 0.13, 95% CI = 0.00 to 0.26, p = 0.046, I2 = 86.60%] and bone mineral density.

The investigators found high dietary selenium intake significantly reduced risk of hip fracture with 56% [OR = 0.44, 95% CI = 0.37 to 0.52, p 0.001, I2 = 65.2%].

The investigators found osteoporosis patients had lower serum selenium level than healthy controls [WMD = -2.01, 95% CI = -3.91 to -0.12, p = 0.037, I2 = 0%].

The investigators concluded persons with higher dietary selenium intake and higher serum selenium have higher bone mineral density. Furthermore, high selenium dietary intake reduces hip fracture.

Original title:
The association between selenium and bone health: a meta-analysis by Xie H, Wang N, […], Wang Y.

Link:
https://boneandjoint.org.uk/article/10.1302/2046-3758.127.BJR-2022-0420.R1

Additional information of El Mondo:
Find more information/studies on selenium and preventing fractures right here.

Circulating concentration of selenium in blood (serum selenium level) can be increased by eating foods that are high in selenium and/or taking selenium supplements.

Objectives:
Does orange juice consumption causally improve lipid profile?

Study design:
This review article included 9 RCTs with a total of 386 participants.
The mean age of the participants ranged from 36 to 56 years.
All the RCTs used a parallel study design.
The dosage of orange juice ranged from 250 to 1000 mL/d.
The duration of interventions ranged from 3 to 12 weeks.

Results and conclusions:
The investigators found orange juice consumption significantly reduced LDL cholesterol (bad cholesterol) levels [WMD  = -8.35 mg/dL, 95% CI = -15.43 to 1.26, p = 0.021, I2 = 45.8%, p = 0.055].

The investigators found in subgroup analysis based on the administered dosage, LDL cholesterol levels significantly decreased following the consumption of >500 mL/d orange juice [WMD = -9.85 mg/dL, 95% CI = -18.18 to -1.52, p = 0.02].
Moreover, the subgroup analyses based on the duration of intervention revealed that the effect of orange juice supplementation on LDL cholesterol levels was significantly greater in trials lasting ≤8 weeks [WMD = -7.91 mg/dL, 95% CI = -15.91 to -36, p = 0·04].
Also, studies conducted on both genders were observed to be significantly more likely to reduce blood LDL-C levels [WMD = -12.61 mg/dL, 95% CI = -21.19 to -4.04, p = 0.004].

The investigators concluded that  at least 500 mL/d orange juice consumption causally reduce LDL cholesterol (bad cholesterol) levels.

Original title:
Orange juice intake and lipid profile: a systematic review and meta-analysis of randomised controlled trials by Amini MR, Sheikhhossein F, […], Askarpour M.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10052563/

Additional information of El Mondo:
Find more information/studies on orange juice consumption, cholesterol and cardiovasculair disease right here.
 

Objectives:
Although relationships between the intake of whole grains and refined grains and the incidence of cardiovascular disease (CVD) events and all-cause mortality have been investigated, the conclusions have been inconclusive. Therefore, this review article has been conducted.

Does consumption of whole grains reduce risk of stroke, coronary heart disease, heart  failure, cardiovascular disease and all-cause mortality?

Study design:
This review article included 68 prospective cohort studies (46 for whole grains and 22 for refined grains) with 1,624,407 participants.

The included studies had follow-up periods between 5.4 y and 26 y, with sample sizes varying from 535 to 461,047 participants.

Based on NOS, the mean score of the included studies was 7.74 for whole grains and 7.45 for refined grains.

Egger’s test and funnel plot did not indicate any publication bias for the relationships between 30g/d increases in whole grain consumption and the risk of stroke [p = 0.481], cardiovascular disease [p= 0.144] or all-cause mortality [p = 0.409].

The quality of meta-evidence for the association between whole grain consumption and risks of stroke, coronary heart disease, heart failure, cardiovascular disease and all-cause mortality was moderate, moderate, low, high and high, respectively.
The quality of evidence for refined grain was low.

Results and conclusions:
The investigators found a significantly reduced risk of 3% for stroke per 30-g increase in daily whole grain consumption [RR = 0.97, 95% CI = 0.96 to 0.99, I2 = 0%].

The investigators found a significantly reduced risk of 6% for coronary heart disease (CHD) per 30-g increase in daily whole grain consumption [RR = 0.94, 95% CI = 0.92 to 0.97, I2 = 54.4%].
Sensitivity analyses indicated that the result was stable.

The investigators found a significantly reduced risk of 8% for cardiovascular disease (CVD) per 30-g increase in daily whole grain consumption [RR = 0.92, 95% CI = 0.88 to 0.96, I2 = 82.9%].
Sensitivity analyses indicated that the result was stable.

The investigators found a significantly reduced risk of 6% for all-cause mortality per 30-g increase in daily whole grain consumption [RR = 0.94, 95% CI = 0.92 to 0.97, I2 = 89.8%].
Sensitivity analyses indicated that the result was stable.

The investigators found whole grain consumption was linearly associated with coronary heart disease [p nonlinearity = 0.231] and nonlinearly associated with cardiovascular disease [p nonlinearity = 0.002] and all-cause mortality [p nonlinearity = 0.001].

The investigators concluded that consumption of at least 30g/d whole grains reduce stroke, coronary heart disease, cardiovascular disease and all-cause mortality.

Original title:
Consumption of whole grains and refined grains and associated risk of cardiovascular disease events and all-cause mortality: a systematic review and dose-response meta-analysis of prospective cohort studies by Hu H, Zhao Y, […], Hu D.

Link:
https://www.sciencedirect.com/science/article/pii/S0002916522105186?via%3Dihub

Additional information of El Mondo:
Find more information/studies on whole grain consumption, cardiovasculair disease and stroke right here.

Objectives:
Prospective cohorts are inconsistent regarding the association between dietary calcium intake and the risk of stroke. Therefore, this review article has been conducted.

Does dietary intake of calcium reduce risk of stroke?

Study design:
This review article included 18 prospective cohort studies witth19,557 stroke cases (persons) among 882,181 participants.

Results and conclusions:
The investigators found a nonlinear association between calcium intake and risk of stroke [p nonlinearity 0.003].

The investigators found compared with the lowest value of zero assumed as the reference, dietary intake of 200 mg/day calcium significantly reduced stroke risk with 5% [95% CI = 0.92 to 0.98].
This protective effect was only found in Asian countries.

The investigators found compared with the lowest value of zero assumed as the reference, dietary intake of 300 mg/day calcium significantly reduced stroke risk with 6% [95% CI = 0.90 to 0.98].
This protective effect was only found in Asian countries.

The investigators found compared with the lowest value of zero assumed as the reference, dietary intake of 500 mg/day calcium significantly reduced stroke risk with 5% [95% CI = 0.90 to 0.99].
This protective effect was only found in Asian countries.

The investigators found no protective effect for stroke at dietary intake of 700 mg/day calcium or higher.

The investigators concluded dietary intake of 200-700 mg/day calcium reduces stroke risk among Asians.

Original title:
Dietary calcium intake and the risk of stroke: Meta-analysis of cohort studies by Wang ZM, Bu XX, […], Nie ZL.

Link:
https://pubmed.ncbi.nlm.nih.gov/36958976/

Additional information of El Mondo:
Find more information/studies on calcium and stroke right here.

Objectives:
Magnesium, an essential cation for numerous cellular processes, is a major component of bone. However, its relationship with the risk of fractures is still uncertain. Therefore, this review article has been conducted.

Do lower serum magnesium concentrations increase risk of incident fractures?

Study design:
This review article included 3 prospective cohort studies and 1 retrospective cohort study with a total of 119,755 participants and a mean follow-up duration of 79 months.
The mean age was 62 years, with a mean percentage of 33% women.
The analyses were adjusted for a mean of 15 potential confounders.
All 4 studies included in the meta-analysis were of high quality (Newcastle-Ottawa Scale of 9 for all).

Results and conclusions:
The investigators found lower serum magnesium concentrations were associated with a significantly higher risk of 58% for incident fractures [RR = 1.579, 95% CI = 1.216 to 2.051, p = 0.001, I2 = 46.9%].
The results were not affected by any heterogeneity [I2 = 31.2%, p = 0.201] nor publication bias [Egger’s test = 0.94 ± 0.43, p = 0.10]. After trimming, the recalculated effect size was only slightly reduced [RR = 1.25, 95% CI = 1.09 to 1.43].
Significant because RR of 1 was not found in the 95% CI of 1.09 to 1.43. RR of 1 means no risk/association.

The investigators concluded lower serum magnesium concentrations increase risk of incident fractures.

Original title:
Association between Serum Magnesium and Fractures: A Systematic Review and Meta-Analysis of Observational Studies by Dominguez LJ, Rodas-Regalado S, […], Barbagallo M.

Link:
https://www.mdpi.com/2072-6643/15/6/1304

Additional information of El Mondo:
Find more information/studies on magnesium and preventing fractures right here.

Circulating concentration of magnesium in blood can be increased by eating foods that are high in magnesium and/or taking magnesium supplements.

Objectives:
Given their potent antioxidation properties, carotenoids play a role in delaying and preventing dementia and mild cognitive impairment (MCI). However, observational studies have found inconsistent results regarding the associations between blood carotenoid levels and the risk of dementia and MCI. Therefore, this review article has been conducted.

Is a lower blood carotenoid level (like lycopene, zeaxanthin, lutein) a risk factor for dementia or mild cognitive impairment?

Study design:
This review article included 23 studies with 1,422 patients with dementia, 435 patients with mild cognitive impairment and 4,753 controls (persons without dementia or mild cognitive impairment).

Results and conclusions:
The investigators found meta-analysis showed that patients with dementia had lower blood lycopene [SMD = -0.521, 95% CI = -0.74 to -0.301], α-carotene [SMD = -0.489, 95% CI = -0.697 to -0.281] β-carotene [SMD = -0.476, 95% CI = -0.784 to -0.168], lutein [SMD = -0.516, 95% CI = -0.753 to -0.279], zeaxanthin [SMD = -0.571, 95% CI = -0.910 to -0.232] and β-cryptoxanthin [SMD = -0.617, 95% CI = -0.953 to -0.281] than the controls.

The investigators found owing to insufficient data, no similar and stable relationship between blood carotenoid levels and mild cognitive impairment was observed.

The investigators concluded lower blood carotenoid level is a risk factor for dementia.

Original title:
Low blood carotenoid status in dementia and mild cognitive impairment: A systematic review and meta-analysis by Wang L, Zhao T, […], Jiang Q.

Link:
https://pubmed.ncbi.nlm.nih.gov/36997905/

Additional information of El Mondo:
Find more information/studies on carotenoids and Alzheimer 's disease right here.

Circulating concentration of lycopene in blood can be increased by eating foods that are high in lycopene and/or taking lycopene supplements.

Objectives:
Does a high antioxidant dietary intake reduce risk of Alzheimer's disease and dementia?

Study design:
This review article included 17 cohort studies with 98,264 participants, of which 7,425 had dementia after 3-23 years of follow-up.

Results and conclusions:
The investigators found a high antioxidant dietary intake significantly reduced the incidence of Alzheimer's disease with 15% [RR = 0.85, 95% CI= 0.79 to 0.92, I2 = 45.5%].
However, this reduced risk was not significant for dementia [RR = 0.84, 95% CI = 0.77 to 1.19, I2 = 54.6%].
Significant because RR of 1 was not found in the 95% CI of 0.79 to 0.92. RR of 1 means no risk/association.

The investigators concluded that a high antioxidant dietary intake reduces Alzheimer's disease.

Original title:
Association of Dietary and Supplement Intake of Antioxidants with Risk of Dementia: A Meta-Analysis of Cohort Studies by Zhao R, Han X, […], You H.

Link:
https://pubmed.ncbi.nlm.nih.gov/36846999/

Additional information of El Mondo:
Find more information/studies on antioxidant and Alzheimer 's disease right here.

Objectives:
Is there a causal relationship between drinking green tea and improving risk factors of cardiovascular disease, like cholesterol, fasting blood sugar, blood pressure, HbA1c, HOMA-IR?

Study design:
This review article included 55 RCTs with 63 effect sizes with 2,487 participants in the green tea group and 2,387 in the placebo group (group without green tea).

The participants’ mean age ranged between 18 and 68.7 years and the period of intervention ranged between 2 to 48 weeks.
Some of the studies enrolled only males or females and some of them included both genders.

TC, LDL, HDL, FBS, HbA1c and DBP-related evidence had moderate quality due to the serious inconsistency reasons. Additionally, it was shown that evidence regarding TG, fasting insulin, SBP and CRP had low quality due to serious imprecision and inconsistency reasons. The evidence relating to HOMA-IR was also downgraded to very low quality because of the serious inconsistency, imprecision and publication bias.

Results and conclusions:
The investigators found green tea supplementation significantly reduced total cholesterol levels (TC) [WMD = -7.62, 95% CI = -10.51 to -4.73, p ≤ 0.001, I2 = 90.9%].
This significantly reduced effect was also found if females or both males and females were included, the dosage of supplementation was less than 1,000 mg/d, the baseline BMI was between 25-29.9 kg/m² and the baseline value of TC was more than 200 mg/dL.

The investigators found green tea supplementation significantly reduced LDL cholesterol levels (LDL-C) [WMD = -5.80, 95% CI = -8.30 to -3.30, p ≤ 0.001, I2 = 90.5%].
This significantly reduced effect was also found if males or both males and females were included, the baseline BMI was between 25-29.9 kg/m² and participants were not affected by T2DM.

The investigators found green tea supplementation significantly reduced fasting blood sugar levels (FBS) [WMD = -1.67, 95% CI = -2.58 to -0.75, p ≤ 0.001, I2 = 72.2%].

This significantly reduced effect was also found when the baseline BMI of participants was between 25-29.9 kg/m², female or both male and female were included, the duration of intervention was more than 12 weeks, the dosage of supplementation was less than 1,000 mg/d and baseline values of FBS were less than 100 mg/dL.

The investigators found green tea supplementation significantly reduced HbA1c levels [WMD = -0.15, 95% CI = -0.26 to -0.04, p = 0.008, I2 = 71.3%].
This significantly reduced effect was also found if the duration of intervention was ≤ 12 weeks, the dosage of supplementation was ≥ 1,000 mg/d, baseline values of HbA1c were less than 6.5%, male or both genders were involved and the baseline value of BMI was ≥ 30 kg/m².

The investigators found green tea supplementation significantly reduced diastolic blood pressure (DBP) [WMD = -0.87, 95% CI = -1.45 to -0.29, p = 0.003, I2 = 92.4%].
This significantly reduced effect was also found if the duration of intervention was ≤ 12 weeks, the dosage of supplementation was less than 1,000 mg/d, baseline values of DBP were more than 80 mmHg and the baseline value of BMI was ≥ 30 kg/m².

The investigators found green tea supplementation significantly increased HDL cholesterol levels (HDL-C) [WMD = 1.85, 95% CI = 0.87 to 2.84, p = 0.010, I2 = 94.4%].
This significantly increased effect was also found if females were included, the baseline BMI was lower more than 30 kg/m², there was no past medical history of T2DM, the duration of intervention was more than 12 weeks, the dosage of supplementation was less than 1,000 mg/d and baseline values of HDL were more than 50 mg/dL.

The investigators found sensitivity analysis showed no significant difference in results with removing one single study for all considered cardiovascular risk factors including lipid profiles, glycemic indices, SBP and DBP and CRP.

The investigators concluded drinking ≤1,000 mg/d green tea may causally improve risk factors of cardiovascular disease. May improve because the RCTs are of low quality.

Original title:
The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis by Zamani M, Kelishadi MR, […], Asbaghi O.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9871939/

Additional information of El Mondo:
Find more information/studies on green tea, lowering blood pressure and cardiovascular diseases right here.

Objectives:
Is there a causal relationship between drinking green tea and lowering blood pressure in healthy individuals?

Study design:
This review article included 9 RCTs with 345 healty individuals in the intervention group (group with green tea) and 335 healthy individuals in the control group (group without green tea).

The mean age of the individuals in the intervention group was 35.89 ± 8.52, while the mean age of the control group was 36.48 ± 7.68.
All studies clearly described allocation randomization, none had incomplete outcome data, and all used appropriate statistical analysis.
The completion rate of the consumption of green tea ranged from 85-100%.
No publication bias was observed in the studies.

Results and conclusions:
The investigators found combined results of the studies showed that green tea was effective in lowering systolic blood pressure in healthy individuals [MD = -2.99, 95% CI = -3.77 to -2.22, p 0.00001, I2 = 0%].

The investigators found combined results of the studies showed that green tea was effective in lowering diastolic blood pressure in healthy individuals [MD= -0.95, 95% CI = -1.62 to -0.27, p = 0.006, I2 = 0%]. 

The investigators concluded in healthy individuals, green tea supplementation reduces systolic blood pressure by 2.99 mmHg and diastolic blood pressure by 0.95 mmHg.

Original title:
Effect of Green Tea on Blood Pressure in Healthy Individuals: A Meta-Analysis by Ayaz EY, Dincer B and Mesci B.

Link:
https://pubmed.ncbi.nlm.nih.gov/36689359/

Additional information of El Mondo:
Find more information/studies on green tea, lowering blood pressure and cardiovascular diseases right here.