Nutrition and health

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. 

Objectives:
Is there an association between serum non-ceruloplasmin copper and Alzheimer's disease risk?

Study design:
This review article included studies carried out from 1996 until March 2013.

Ten studies were analyzed in the meta-analysis for Non-Cp copper and % Non-Cp copper reaching a pooled total of 599 Alzheimer's disease subjects and 867 controls.
For Adj-Cp copper, 14 studies were analyzed with a pooled total of 879 Alzheimer's disease subjects and 1712 controls.
27 studies were considered for systemic total copper meta-analysis, with a pooled total of 1393 Alzheimer's disease subjects and 2159 controls.

Results and conclusions:
The investigators found all copper indices analyzed were significantly higher in Alzheimer's disease subjects compared to healthy controls.

The investigators concluded serum non-ceruloplasmin copper is higher in Alzheimer's disease.

Original title:
Meta-analysis of serum non-ceruloplasmin copper in Alzheimer's disease by Squitti R, Simonelli I, […], Bush AI.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/24072069

Additional information of El Mondo:
Find more studies/information on elderly and copper.

Objectives:
Does DHA, alone or combined with EPA, contribute to improved memory function in older adults with mild memory complaints?

Study design:
This review article included 15 intervention trials and 13 observational studies. Most intervention trials were conducted with subjects ≥ 45 years of age (n = 11). The majority of studies were conducted in subjects without cognitive complaints (n = 9) and ranged from 28-730 days in duration, averaging 4-6 months.

Results and conclusions:
The investigators found episodic memory of subjects with mild memory complaints significantly improved in response to DHA supplementation, alone or in combination with EPA [p 0.004].

The investigators found regardless of cognitive status at baseline, >1 g/day DHA/EPA significantly improved episodic memory of subjects with mild memory complaints [p 0.04].

The investigators found there was a trend for episodic memory improvement in response to supplementation in subjects 45 years or older [p 0.058].

The investigators found DHA intake above the mean DHA level studied (580 mg/day) significantly improved episodic memory in all subjects [p 0.009] and in subjects with mild memory complaints [p 0.019]. Significant means that there is an association with a 95% confidence.

The investigators found observational studies supported a beneficial association between intake/blood levels of DHA/EPA and memory function in older adults.

The investigators concluded DHA (>580 mg/day), alone or combined with EPA (>1 g/day DHA/EPA), contributes to improved memory function in older adults (45 years or older) with mild memory complaints.

Original title:
Docosahexaenoic Acid and Adult Memory: A Systematic Review and Meta-Analysis by Yurko-Mauro K, Alexander DD and Van Elswyk ME.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364972/

Additional information of El Mondo:
Find more studies/information on elderly and EPA&DHA.

This meal provides at least 580 mg DHA.
1 g/day DHA/EPA corresponds to meals providing 4 days of DHA&EPA.

Episodic memory is the type of long-term, declarative memory in which we store memories of personal experiences that are tied to particular times and places.
Some examples of episodic memory:

• Your skiing vacation last winter;
• The first time you traveled by airplane;
• Your first high school day.