Voeding en gezondheid

Objectives:
Clinical trials of vitamin K supplementation have reported conflicting results on its effect on insulin sensitivity. Therefore, this meta-analysis (systematic review) has been conducted.

Does vitamin K supplementation improve insulin sensitivity?

Study design:
This review article included 8 RCTs involving 1,077 participants. A wide variety of participants were enrolled, including older men, postmenopausal women, prediabetic premenopausal women and participants with a history of diabetes, hypertension, or vascular disease.
The number of participants ranged from 42 to 452. The study duration varied from 4 weeks to 3 years.
5 RCTs evaluated vitamin K1 ranging from 500 to 1,000 µg/d. 2 RCTs used vitamin K2 (MK-4) 1.5 and 45 mg/d and 1 RCT assessed vitamin K2 (MK-7) 100 µg/d.

All the studies were regarded as high quality.

Heterogeneity was detected in the meta-analysis.

Results and conclusions:
The investigators found that vitamin K supplementation had no effect on homeostasis model assessment of insulin resistance (HOMA-IR), fasting plasma glucose (FPG) and fasting plasma insulin (FPI). The pooled mean difference = -0.14, [95% CI = -0.35 to 0.07, p = 0.19], 0.02 mmol/L [95% CI = -3.11 to 3.70, p = 0.86] and -0.34 µIU/mL [95% CI = -1.13 to 0.45, p =0.40] for HOMA-IR, FPG and FPI, respectively.

The investigators found that vitamin K supplementation had no effect on leptin [mean difference = 0.77 ng/mL, 95% CI = -1.32 to 2.86].

The investigators found that vitamin K supplementation failed to show a significant effect on IL-6 or CRP levels. The pooled mean differences were 0.14 pg/mL [95% CI = -0.69 to 0.97] and -0.49 mg/L [95% CI = -1.18 to 0.20] for IL-6 and CRP, respectively

The investigators found that vitamin K supplementation had no effect on adiponectin [pooled mean difference = 0.82 µg/mL [95% CI: -0.89 to 2.53].

The investigators concluded that vitamin K supplementation does not improve insulin sensitivity. Given the limited evidence available and the heterogeneity in the study results, further well-designed, large sample size randomized controlled trials are warranted. Different forms and doses of vitamin K should be explored in various populations and other surrogate markers for insulin sensitivity should be measured to better establish any beneficial effects and their clinical relevance.

Original title:
Effect of vitamin K supplementation on insulin sensitivity: a meta-analysis and Suksomboon N, Poolsup N and Darli Ko Ko H.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5422317/

Additional information of El Mondo:
Find more information/studies on vitamin K and diabetes right here.
An improved insulin sensitivity decreases diabetes risk.

Onderzoeksvraag:
Verlaagt het eten van zink of ijzer de kans op het krijgen van een depressie?

Studieopzet:
Dit overzichtsartikel bevatte 9 studies over het eten van zink en 3 studies over het eten van ijzer.

Resultaten en conclusies:
De onderzoekers vonden dat het eten van veel zink vergeleken met weinig, de kans op het krijgen van een depressie significant met 33% [gepoolde RR = 0.67, 95% BI = 0.58-0.76] verlaagde.

De onderzoekers vonden dat het eten van veel ijzer vergeleken met weinig, de kans op het krijgen van een depressie significant met 43% [gepoolde RR = 0.57, 95% BI = 0.34-0.95] verlaagde.

De onderzoekers vonden in zowel cohort studies als cross-sectionele studies dat het eten van veel zink vergeleken met weinig, de kans op het krijgen van een depressie significant verlaagde.

De onderzoekers concludeerden dat het eten van veel zink de kans op het krijgen van een depressie verlaagde.

Oorspronkelijke titel:
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

Extra informatie van El Mondo:
Vind hier meer studies over zink en depressie.

Deze maaltijden bevatten veel zink.