Nutritional advice

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:
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 relationship between serum 25(OH)D (vitamin D blood level) and mortality risk in the general population?

Study design:
This review article included 14 prospective cohort studies that involved 5562 deaths out of 62548 individuals.
In the parametric model, which is based on 11 studies and 59231 individuals, the lowest quantile as the reference category has been used.

Evidence of heterogeneity for the RR was apparent when highest were compared with lowest categories [p = 0.008, I2 = 58%].

There was no evidence of publication bias.

Results and conclusions:
The investigators found for “highest compared with lowest” categories of 25(OH)D, a significant reduced risk of 29% for mortality [RR = 0.71, 95% CI = 0.50-0.91].

The investigators found in the parametric model, the estimated summary RRs of mortality were 0.86 [95% CI = 0.82-0.91], 0.77 [95% CI = 0.70-0.84] and 0.69 [95% CI = 0.60-0.78] for individuals with an increase of 12.5, 25 and 50 nmol 25(OH)D serum values/L, respectively, from a median reference category of ∼27.5 nmol/L.
However, no significant decrease in mortality was found above ∼87.5 nmol/L.

The investigators concluded there is a nonlinear decrease in mortality risk as circulating 25(OH)D increases, with optimal concentrations ∼75-87.5 nmol/L. Because many adults do not achieve these 25(OH)D values, large prospective randomized trials are urgently needed to investigate whether vitamin D supplementation is able to reduce mortality risk in the general population.

Original title:
Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies by Zittermann A, Iodice S, [...], Gandini S.

Link:
http://ajcn.nutrition.org/content/95/1/91.full

Additional information of El Mondo:
Find more information/studies on vitamin D right here. 

Objectives:
Does soy isoflavone reduce the frequency and severity of hot flashes?

Study design:
This review article included 19 trials (13 included hot flash frequency, of which 10 for severity and 3 for composite scores).
17 trials were selected for meta-analyses to clarify the effect of soybean isoflavones on hot flash frequency (13 trials) and severity (9 trials).

Results and conclusions:
The investigators found intake of soy isoflavones (median = 54 mg aglycone equivalents) for 6 weeks to 12 months significantly reduced the frequency (combined fixed-effect and random effects model) of hot flashes by 20.6% [95% CI = -28.38 to -12.86, p 0.00001] compared with placebo [p heterogeneity = 0.0003, I2 = 67% for random effects model].

The investigators also found isoflavones significantly reduced hot flash severity by 26.2% [95% CI = -42.23 to -10.15, p = 0.001] compared with placebo [p heterogeneity 0.00001, I2 = 86% for random effects model].

The investigators found isoflavone supplements providing more than 18.8 mg of genistein (the median for all studies) were more than twice as potent at reducing hot flash frequency than lower genistein supplements.

The investigators concluded soy isoflavone supplements (54 mg per day for 6 weeks to 12 months), derived by extraction or chemical synthesis, are significantly more effective than placebo in reducing the frequency and severity of hot flashes. Additional studies are needed to further address the complex array of factors that may affect efficacy, such as dose, isoflavone form, baseline hot flash frequency and treatment duration.

Original title:
Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials by Taku K, Melby MK, […], Messina M.

Link:
http://journals.lww.com/menopausejournal/Abstract/2012/07000/Extracted_or_synthesized_soybean_isoflavones.11.aspx

Additional information of El Mondo:
Find more studies/information on elderly and isoflavones right here.
 

Objectives:
In view of the vital role of oxidative stress in the pathogenesis of Alzheimer's disease (AD), the potential of antioxidant supplements to prevent AD have gained much interest, while there are conflicting results on this topic in recent years. Therefore, this review article has been conducted.

Does dietary intake of vitamin C and E and β-carotene decrease risk of Alzheimer's disease?

Study design:
This review article included 7 articles (dietary intake, but no supplements).

Results and conclusions:
The investigators found a significant decreased risk for Alzheimer disease of 24% [pooled relative risk = 0.76 95% CI = 0.67-0.84] for dietary intake of vitamin E and of 17% [pooled relative risk = 0.83, 95% CI = 0.72-0.94] for dietary intake of vitamin C.

However, the investigators found a non-significant decreased risk of 12% [pooled relative risk = 0.88, 95% CI = 0.73-1.03] for dietary intake of β-carotene.

The investigators concluded dietary intakes of vitamin C and E lower the risk of Alzheimer's disease, with vitamin E exhibiting the most pronounced protective effects. The findings will be of significance to the prevention and interventional treatment of Alzheimer's disease.

Original title:
Dietary intakes of vitamin E, vitamin C, and β-carotene and risk of Alzheimer's disease: a meta-analysis by Li FJ, Shen L and Ji HF.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/22543848

Additional information of El Mondo:
Find more information/studies on vitamin C and E and carotenoids right here.