Nutrition and health

Objectives:
Zinc is an essential trace element for living organisms and their biological processes. Zinc plays a key role in more than 300 enzymes and it is involved in cell communication, proliferation, differentiation and survival. Zinc also plays a role in regulating the immune system with implications in pathologies where zinc deficiency and inflammation are observed. Therefore, this meta-analysis (systematic review) has been conducted.

Do zinc deficiency increase risk of autoimmune disorders?

Study design:
This review article included 62 case-control studies.

The manner of collecting and investigating zinc samples was very heterogeneous.

Results and conclusions:
The investigators found in fixed model that serum zinc concentration of autoimmune disease patients was significantly lower than in controls [mean effect = -1.19, 95% CI = -1.26 to -1.11].

The investigators found in fixed model that plasma zinc concentration of autoimmune disease patients was significantly lower than in controls [mean effect = -3.97, 95% CI = -4.08 to -3.87].

The investigators concluded that a deficiency of zinc in serum and plasma increases risk of autoimmune disorders in humans.

Original title:
Zinc Status and Autoimmunity: A Systematic Review and Meta-Analysis by Sanna A, Firinu D, […], Valera P.

Link:
http://www.mdpi.com/2072-6643/10/1/68/htm

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

An autoimmune disease is a condition in which your immune system mistakenly attacks your body. These are the most common autoimmune diseases:  

1. Addison’s disease: Caused by an adrenal hormone insufficiency. Addison’s disease can lead to muscle weakness and fatigue, nausea, weight loss, irritability, low blood pressure, low blood sugar and depression.
2. Celiac disease (gluten allergy): Celiac disease is a reaction to gluten (found in barley, rye and wheat) that causes damage to the lining of the small intestine.
3. Graves’ disease: Caused by extremely overactive thyroid gland. People who have Graves’ disease may have difficulty sleeping, bulging of the eyes, irritability, brittle hair, unexplained weight loss, sensitivity to heat, muscle weakness, light menstrual periods and shakiness of the hands. On the other hand, some people with Graves’ disease may experience no symptoms at all.
4. Hashimoto’s disease: Caused by inflammation of the thyroid gland. Although sometimes no symptoms occur, Hashimoto’s thyroiditis often results in a goiter (enlargement of the thyroid gland, which may be visible as a bulge in the neck), weight gain, fatigue, muscle weakness, depression, cold sensitivity, dry hair and skin, and constipation.
5. Inflammatory bowel disease: This disease refers to a group of inflammatory diseases of the colon and small intestine.
6. Multiple Sclerosis or MS: This disease affects the brain and spinal cord. People who have MS may experience weakness, trouble with balance and coordination, problems speaking and walking, tremors, paralysis and numbness in the extremities.
7. Psoriasis: This is a skin condition that causes redness and irritation as well as thick, flaky, silver-white patches.
8. Pernicious anemia: Caused by the inability to absorb vitamin B12 leading to a decrease in red blood cells.
9. Reactive arthritis: Caused by inflammation of joints, the urethra and eyes.
10. Raynaud’s phenomenon: People with Raynaud’s have a problem with blood flow, resulting in numbness, tingling of the fingers, discoloration, toes and tip of the nose with exposure to cold temperatures.
11. Rheumatoid arthritis: In rheumatoid arthritis, autoimmunity causes the immune system to attack tissues in the joints. It typically affects the small joints in your hands and feet causing painful swelling, stiffness and loss of movement in the joints that can eventually result in bone erosion and joint deformity.
12. Scleroderma: Scleroderma is a connective tissue disease that causes changes in skin, muscles, blood vessels and internal organs.
13. Sjögren’s syndrome: Caused by destruction of the glands that produce tears and saliva causing dry eyes and mouth.
14. Systemic lupus erythematosus: In lupus, antibodies made by the immune system attack the body. Systemic lupus erythematosus can affect skin, kidneys, joints and brain.
15. Type 1 diabetes: In type 1 diabetes, the immune system attacks cells in the pancreas that produce insulin. When your insulin levels are insufficient, your body cannot control your blood glucose level, which can lead to a number of problems, including kidney failure, stroke, vision loss, circulation problems and heart disease.

Objectives:
Anemia is a worldwide public health problem that can be related to many causes, including vitamin A deficiency. Therefore, this review article (meta-analysis) has been conducted.

The aim of this review article is to examine the effect of vitamin A supplementation (VAS) on iron status biomarkers and anemia in humans.

Study design:
This review article included 21 clinical trials and 2 cohort studies, with children, teenagers, pregnant or lactating women.

Results and conclusions:
The investigators found clinical trials showed that vitamin A supplementation significantly reduced risk of anemia by 26% and raised hemoglobin levels, compared to non-treated group, independent of the life stage.

The investigators found clinical trials showed that vitamin A supplementation did not alter the prevalence of iron deficiency among children and teenagers [RR = 0.82, 95% CI = 0.60 to 1.12, p = 0.204].
However, a significant increase in serum ferritin levels was observed in trials conducted among pregnant and lactating women [WMD = 6.61 μg/L, 95% CI = 6.00 to 7.21 μg/L, p 0.001]. Significant because the found p value of 0.001 was lower than p value of 0.05.

The investigators concluded that vitamin A supplementation alone reduces risk of anemia, by improving hemoglobin and ferritin levels in individuals with low serum retinol levels.

Original title:
Effect of vitamin A supplementation on iron status in humans: a systematic review and meta-analysis by da Cunha MS, Campos Hankins NA and Arruda SF.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29336593

Additional information of El Mondo:
Find more information/studies on food fortification/malnutrition, vitamin A and study design/meta-analysis/significant right here.

Objectives:
Does exercise training delay the decline in cognitive function among individuals who are at risk of/or have Alzheimer's disease?  

Study design:
This review article included 19 controlled studies with 23 interventions including 1,145 subjects with a mean age of 77.0 ± 7.5.
The studies included an exercise-only intervention and a nondiet, nonexercise control group and reported pre- and post-intervention cognitive function measurements.

Most subjects were at risk of Alzheimer's disease because they had mild cognitive impairment (64%) or a parent diagnosed with Alzheimer's disease (1%) and 35% presented with Alzheimer's disease.

Exercise interventions were performed 3.4 ± 1.4 days per week at moderate intensity (3.7 ± 0.6 metabolic equivalents) for 45.2 ± 17.0 minutes per session for 18.6 ± 10.0 weeks and consisted primarily of aerobic exercise (65%).

Results and conclusions:
The investigators found overall, there was a modest favourable effect of exercise on cognitive function [d+ = 0.47, 95% CI = 0.26 to 0.68].

The investigators found within-group analyses revealed that exercise improved cognitive function [d+w = 0.20, 95% CI = 0.11 to 0.28], whereas cognitive function declined in the control group [d+w = -0.18, 95% CI = -0.36 to 0.00].

The investigators found within-group analyses revealed that aerobic exercise had a moderate favourable effect on cognitive function [d+w = 0.65, 95% CI = 0.35 to 0.95), but other exercise types did not [d+w = 0.19, 95% CI = -0.06 to 0.43].

The investigators concluded that exercise training (3.4 days per week at moderate intensity for 45.2 minutes per session during 18.6 weeks) delays the decline in cognitive function that occurs in individuals who are at risk of/or have Alzheimer's disease, with aerobic exercise having the most favourable effect. Additional randomized controlled clinical trials that include objective measurements of cognitive function are needed to confirm these findings.

Original title:
Can Exercise Improve Cognitive Symptoms of Alzheimer's Disease? A Meta-Analysis by Panza GA, Taylor BA, […], Pescatello LS.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29363108

Additional information of El Mondo:
Find here more information/studies about elderly and sport nutrition.

Metabolic Equivalents (METs) are commonly used to express the intensity of physical activities.
MET is the ratio of a person's working metabolic rate relative to their resting metabolic rate.
One MET is defined as the energy cost of sitting quietly and is equivalent to a caloric consumption of 1 kcal/kg/hour.

Objectives:
There are some indications of regional differences in the association between fish consumption and clinical outcomes. Therefore, this review article (meta-analysis) has been conducted.  

Are there regional differences in the association between fish consumption and risk of all-cause mortality and cardiovascular (CVD) mortality?

Study design:
This review article included 14 prospective cohort studies (10 publications) with 911,348 participants, of which 75,451 incident deaths.

Results and conclusions:
The investigators found dose-response meta-analysis showed a 20 g/d increment in fish consumption significantly reduced risk of cardiovascular mortality with 4% [relative risk = 0.96, 95% CI = 0.94-0.98, I2 = 0%, n = 8]. However, subgroup analysis resulted in a significant association only in Asian studies and not in Western studies.

The investigators found dose-response meta-analysis showed a 20 g/d increment in fish consumption significantly reduced risk of all-cause mortality with 2% [relative risk = 0.98, 95% CI = 0.97-1.00, I2 = 81.9%, n = 14]. However, subgroup analysis resulted in a significant association only in Asian studies and not in Western studies.

The investigators found analysis of Western studies suggested a nearly U-shaped association, with a nadir at fish consumption of 20 g/d in analysis of both outcomes. Meanwhile, the associations appeared to be linear in Asian studies.

The investigators concluded that fish consumption, particularly 20 g/d reduces boh risk of cardiovascular mortality and all-cause mortality. Furthermore, there is potential evidence of regional differences in the association between fish consumption and mortality. Therefore, it may be helpful to examine the associations by considering types of fish consumed and methods of fish preparation.

Original title:
Fish consumption and risk of all-cause and cardiovascular mortality: a dose-response meta-analysis of prospective observational studies by Jayedi A, Shab-Bidar S, […], Djafarian K.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29317009

Additional information of El Mondo:
Find more information/studies on cardiovascular disease and fish consumption right here.