Nutritional advice

Objectives:
The associations between dietary zinc and iron intake and risk of depression remain controversial. Therefore, this meta-analysis (systematic review) has been conducted.

Do dietary zink and iron intake decrease risk of depression?

Study design:
This review article included a total of 9 studies for dietary zinc intake and 3 studies for dietary iron intake. 

Results and conclusions:
The investigators found for the highest versus lowest dietary zinc a significant reduced risk of 33% [pooled RR = 0.67, 95% CI = 0.58-0.76] for depression.

The investigators found for the highest versus lowest dietary iron a significant reduced risk of 43% [pooled RR = 0.57, 95% CI = 0.34-0.95] for depression.

The investigators found in subgroup analysis by study design, the inverse association between dietary zinc intake and risk of depression remained significant in cohort studies and cross-sectional studies.

The investigators found the pooled RRs (95% CIs) for depression did not substantially change in the influence analysis and subgroup analysis by adjustment for body mass index (BMI).

The investigators concluded dietary zinc intake reduces risk of depression.

Original title:
Dietary zinc and iron intake and risk of depression: A meta-analysis by Li Z, Li B, [...], Zhang D.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28189077

Additional information of El Mondo:
Find here more information/studies about zinc and review article/95% CI.

Objectives:
Arthritis patients often take fish oil supplements to alleviate symptoms, but limited evidence exists regarding their efficacy. Therefore, this meta-analysis (systematic review) has been conducted.

Do taking marine oil supplements alleviate pain in arthritis patients?

Study design:
This review article included 42 randomized trials; 30 trials reported complete data on pain.

The trials used treatment durations from 2 weeks to 18 months, with doses of EPA from 0.013 to 4.050 g/day and doses of DHA from 0.010 to 2.700 g/day.
Most trials used marine oil from whole fish, but some used cod liver oil, mussel extracts, seal oil and krill oil.

The trials included 2751 patients with a mean age of 53.8 years (range of mean age of 10-68 years) and the mean disease duration was 9.7 years (range 2.3-19.0 years).

Results and conclusions:
The investigators found a favorable effect [SMD = -0.24, 95% CI = -0.42 to -0.07, I2 = 63%] for using marine oil supplements.

The investigators found in 22 trials a significant effect in patients with rheumatoid arthritis [SMD = -0.21, 95% CI = -0.42 to -0.004] for using marine oil supplements.

The investigators also found in 3 trials a significant effect for other or mixed diagnoses [SMD = -0.63, 95% CI = -1.20 to -0.06] for using marine oil supplements, but no significant effect was found in osteoarthritis patients [5 trials: SMD = -0.17, 95% CI = -0.57 to 0.24].

The investigators found a significant, beneficial effect on pain for marine oil with an EPA/DHA ratio >1.5.

The investigators found a significant positive association between SMD and total dose of EPA and DHA [slope β, 0.13 (g/day), 95% CI = 0.04 to 0.22, p = 0.006], indicating less effect at higher dose, but there was no duration-response relationship [p = 0.568].

The investigators concluded using marine oil supplements (with an EPA/DHA ratio >1.5) alleviates pain in rheumatoid arthritis patients.

Original title:
Marine Oil Supplements for Arthritis Pain: A Systematic Review and Meta-Analysis of Randomized Trials by Senftleber NK, Nielsen SM, […], Christensen R.

Link:
http://www.mdpi.com/2072-6643/9/1/42/htm

Additional information of El Mondo:
Find here more information/studies about EPA&DHA and chronic diseases.

Objectives:
The role of vitamin D status in the etiology of allergic diseases is uncertain. Therefore, this meta-analysis (systematic review) has been conducted.

Study design:
This review article included a total of 21 observational studies.

Results and conclusions:
The investigators found children with serum 25(OH)D ≥75 nmol/L had significantly reduced odds of aeroallergen sensitization, but neither vitamin D intake during pregnancy nor vitamin D supplementation in infancy were associated with risk of allergic rhinitis.

The investigators found compared to those with serum 25(OH)D 50 nmol/L, individuals with serum 25(OH)D ≥75 nmol/L had a significant decreased risk of 29% [OR = 0.71, 95% CI = 0.56-0.89, p = 0.04] for allergic rhinitis.
However, this association was mainly observed in adult men; prevalence of allergic rhinitis (AR) was lower in men with serum 25(OH)D ≥75 nmol/L compared to men with serum 25(OH)D 50 nmol/L, while this association was not observed in women.

The investigators concluded serum 25(OH)D ≥75 nmol/L reduced odds of aeroallergen sensitization in children and risk of allergic rhinitis in men.

Original title:
Vitamin D status, aeroallergen sensitization, and allergic rhinitis: A systematic review and meta-analysis by Aryan Z, Rezaei N and Camargo CA Jr.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28102718

Additional information of El Mondo:
Find here more information/studies about vitamin D and chronic diseases.