Nutritional advice

Objectives:
What are the effects of olive oil consumption compared with other plant oils on blood lipids?

Study design:
This review article included 27 RCTs, comprising 1,089 participantes.

Results and conclusions:
The investigators found compared to other plant oils, HDL cholesterol levels (good cholesterol) increased significantly more for olive oil consumption [WMD = 1.37 mg/dL, 95% CI = 0.4 to 2.36].

The investigators found, however, olive oil consumption reduced total cholesterol levels [WMD = 6.27 mg/dL, 95% CI = 2.8 to 10.6], LDL cholesterol levels (bad cholesterol) [WMD = 4.2 mg/dL, 95% CI = 1.4 to 7.01] and triglyceride levels [WMD = 4.31 mg/dL, 95% CI = 0.5 to 8.12] significantly less than other plant oils.

The investigators found that there were no significant effects on Apo lipoprotein A1 and Apo lipoprotein B.

The investigators concluded that olive oil consumption decreases serum total cholesterol, LDL cholesterol and triglyceride levels less but increases HDL cholesterol levels more than other plant oils.

Original title:
Comparison of blood lipid-lowering effects of olive oil and other plant oils: A systematic review and meta-analysis of 27 randomized placebo-controlled clinical trials by Ghobadi S, Hassanzadeh-Rostami Z, […], Faghih S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29420053

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Objectives:
In 2016, the World Health Organization (WHO) recommended point-of-use fortification of complementary foods with iron-containing micronutrient powders to improve iron status and reduce anaemia in children at risk of anaemia. This recommendation continues to be debated. Therefore, this review article (meta-analysis) has been conducted.

Does point-of-use fortification of foods with iron-containing micronutrient powders reduce anaemia in children at risk of anaemia?

Study design:
This review article included trials.

Results and conclusions:
The investigators found in an arbitrarily selected setting and with adherence as obtained under trial conditions, a small increase in haemoglobin concentration in preschool children with point-of-use fortification of foods with iron-containing micronutrient powders, by only 3.9 g/L, with the upper limit of the 95% CI virtually excluding an effect beyond 5.5 g/L. However, the attenuated effect that is likely to be achieved under real-world conditions is even lower.

The investigators found point-of-use fortification with NaFeEDTA improved geometric mean plasma ferritin concentrations by only 4 μg/L [95% CI = 29.7 to 33.7 μg/L].

The investigators concluded point-of-use fortification of foods with micronutrient powders containing iron gives only a small increase in haemoglobin concentration in preschool children. However, attention should be given to the phenomenon that small group differences in the distribution of continuous outcomes (haemoglobin concentration, ferritin concentrations) can give a false impression of relatively large effects on the prevalence of the dichotomised outcomes (anaemia, iron deficiency).

Original title:
Micronutrient powders to combat anaemia in young children: do they work? by Verhoef H, Teshome E and Prentice AM.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5776757/

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Objectives:
Does vegetable and/or fruit consumption reduce metabolic syndrome (MetS)?

Study design:
This review article included 20 cross-sectional studies, 1 case-control study and 5 cohort studies.

Results and conclusions:
The investigators found in 16 studies when comparing the highest versus the lowest category of vegetable consumption a significantly reduced risk of 11% [overall multivariable-adjusted RR = 0.89, 95% CI = 0.85-0.93, p 0.001] for metabolic syndrome.

The investigators found in 16 studies when comparing the highest versus the lowest category of fruit consumption a significantly reduced risk of 19% [overall multivariable-adjusted RR = 0.81, 95% CI = 0.75-0.88, p 0.001] for metabolic syndrome.

The investigators found in 8 studies when comparing the highest versus the lowest category of vegetable and fruit consumption a significantly reduced risk of 25% [overall multivariable-adjusted RR = 0.75, 95% CI = 0.63-0.90, p = 0.002] for metabolic syndrome.

The investigators concluded that vegetable and/or fruit consumption is negatively associated with metabolic syndrome. However, more well-designed prospective cohort studies are needed to elaborate the concerned issues further.

Original title:
Associations of vegetable and fruit consumption with metabolic syndrome. A meta-analysis of observational studies by Zhang Y and Zhang DZ.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29506604

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Objectives:
Is there a dose-response association between serum 25(OH)D (vitamin D level in blood) and risk of dementia and Alzheimer's disease (AD)?

Study design:
This review article included 7 prospective cohort studies and 1 retrospective cohort study involving 1,953 cases of dementia and 1,607 cases of Alzheimer's disease among a total of 28,354 participants.

Results and conclusions:
The investigators found no association between vitamin D insufficiency (10-20 ng/mL) and risk of dementia [pooled HR = 1.09, 95% CI = 0.95 to 1.24].
No association because RR of 1 was found in the 95% CI of 0.95 to 1.24. RR of 1 means no risk/association.

The investigators found no association between vitamin D insufficiency (10-20 ng/mL) and risk of Alzheimer's disease [pooled HR = 1.19, 95% CI = 0.96 to 1.41].

The investigators found vitamin D deficiency (10 ng/mL) significantly increased risk of dementia with 33% [pooled HR = 1.33, 95% CI = 1.08 to 1.58].
Significantly means it can be said with a 95% confidence that vitamin D deficiency really increased the risk of getting dementia with 33%. 

The investigators found vitamin D deficiency (10 ng/mL) non-significantly increased risk of Alzheimer's disease with 31% [pooled HR = 1.31, 95% CI = 0.98 to 1.65].

The investigators found lower risk of dementia was observed at serum 25(OH)D of 25 ng/mL, whereas the risk of Alzheimer's disease decreased continuously along with the increase of serum 25(OH)D up to 35 ng/mL.

The investigators concluded that vitamin D (serum 25(OH)D) levels of 25 to 35 ng/mL decrease risk of dementia and Alzheimer's disease. However, there is no conclusive evidence regarding serum 25(OH)D levels of >35 ng/mL.

Original title:
Vitamin D status and risk of dementia and Alzheimer's disease: A meta-analysis of dose-response by Jayedi A, Rashidy-Pour A and Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29447107

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Objectives:
Individuals with mild cognitive impairment (MCI) are at high risk for developing dementia. Physical exercise is a promising intervention for cognitive decline. Systematic reviews regarding the effects of physical exercise on cognitive and psychological outcomes among MCI patients are limited and a systematic review exploring the effects of exercise modalities on the results has not been conducted. Therefore, this review article has been conducted.

Do individuals with mild cognitive impairment benefit from physical exercise?

Study design:
This review article included 11 studies. The exercise interventions can be classified into 3 types: (a) aerobic exercise, (b) resistance exercise and (c) multi-modal exercise.

Results and conclusions:
The investigators found that physical exercise had beneficial effects for global cognition [SMD = 0.30, 95% CI = 0.10-0.49, p = 0.002].

The investigators found subgroup analysis demonstrated that aerobic exercise programmes were consistently associated with medium effect size [SMD = 0.54-0.58].

The investigators found, however, the effects of physical exercise on domain-specific cognitive function and psychological outcomes in mild cognitive impairment patients remained inconclusive.

The investigators found sensitivity analysis showed that types of control exerted influence on the outcomes.

The investigators concluded that physical exercise, aerobic exercise in particular, benefits global cognition in mild cognitive impairment patients. The evidence of physical exercise on domain-specific cognitive function and psychological outcomes remains unclear, more trials with rigorous study design are necessary to provide the evidence.

Original title:
The effectiveness of physical exercise on cognitive and psychological outcomes in individuals with mild cognitive impairment: A systematic review and meta-analysis by Song D, Yu DSF, […], Lei Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29334638

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Objectives:
Plasmodium vivax (P. vivax) is the most geographically widespread species among human malaria parasites. Immunopathological studies have shown that platelets are an important component of the host innate immune response against malaria infections. Therefore, this review article (meta-analysis) has been conducted.

The aim of this review article is to quantify thrombocytopaenia in plasmodium vivax malaria patients and to determine the associated risks of severe thrombocytopaenia in patients with plasmodium vivax malaria compared to patients with plasmodium falciparum malaria.

Study design:
This review article included 58 observational studies (5,536 patients had thrombocytopaenia among a total of 29,664 patients investigated) across 12 endemic countries.  
29 of 58 studies were prospective studies. Of them, the vast majority of participants infected with P. vivax (66%, 19 552/29664) were from a single large study conducted in Indonesia. Half of the studies were conducted in India (50%) and the study period covered the years 1988-2015. Only 25% of the included studies had PCR confirmation of parasite species.

Not all studies included in this review used the same methods for platelet “labelling”.

Results and conclusions:
The investigators found pooled analysis showed that 18.7% [95% CI = 17.0-20.2%] of patients with P. vivax malaria had platelet counts  150 000/mm³. Of these, 10.1% [95% CI = 9.0-10.8%] of the patients infected with P. vivax had either severe thrombocytopaenia (9%) or very severe thrombocytopaenia (13%).
There was an absence of statistical heterogeneity [I2 = 0%], suggesting a high level of homogeneity between studies in each gradient of thrombocytopaenia.

The investigators found a meta-analysis of 11 observational studies showed an equal risk of developing severe/very severe thrombocytopaenia between the patients with P. vivax malaria and those with P. falciparum malaria [OR = 1.98, 95% CI = 0.92-4.25], indicating that thrombocytopaenia is as equally a common manifestation in P. vivax and P. falciparum malaria patients.
In a subgroup of 3 studies, a pooled analysis showed patients with severe P. vivax malaria and those with severe P. falciparum malaria had an equal risk of developing severe/very severe thrombocytopaenia.
Further stratification by age groups showed children with severe P. vivax malaria (60/278) had a higher risk of developing very severe thrombocytopaenia than in those with severe P. falciparum malaria (13/145) [OR = 2.80, 95% CI = 1.48-5.29]. However an equal risk was observed for adult severe cases with P. vivax malaria and those with P. falciparum malaria [45/186 vs 70/207, OR = 1.19, 95% CI = 0.51-2.77, p = 0.22].

The investigators found in a subset of 4 studies a decreased platelet counts in patients with P. vivax malaria compared to the healthy controls [p  0.001 in all four studies].

The investigators found a pooled analysis of 4 studies showed that 15% [95% CI = 9-21%] of P. vivax malaria patients with thrombocytopaenia developed minor bleeding episodes. These bleeding manifestations were epistaxis, haematemesis, petechiae and purpura.

The investigators found a pooled analysis of 2 studies with PCR confirmed parasite species showed an equal risk of mortality with severe thrombocytopaenia in P. vivax malaria patients (10.2%, 5/49) and P. falciparum malaria patients (14%, 8/57) [OR = 1.16, 95% CI = 0.30-4.60, p = 0.87].

The investigators concluded there is some evidence of the clinical relevance of severe thrombocytopaenia in P. vivax malaria patients. However, due to the low number of studies with small sample sizes within the subset of studies that provided clinically relevant information, the confidence in the estimates is limited. Therefore, there is a need for future well designed, large-scale, prospective studies among patients infected with P. vivax from different countries and epidemiological settings with various age and gender groups represented to substantiate these findings.

Original title:
Severe thrombocytopaenia in patients with vivax malaria compared to falciparum malaria: a systematic review and meta-analysis by Naing C and Whittaker MA.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5808388/

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Objectives:
Does poultry intake reduce risk of stroke?

Study design:
This review article included 7 prospective cohort studies involving 354,718 participants.

Results and conclusions:
The investigators found for the highest versus lowest categories of poultry intake a non-significantly reduced risk of 8% for total stroke [pooled RR = 0.92, 95% CI = 0.82-1.03, I2 = 19.8%, p = 0.28].

The investigators found in subgroup analysis for the highest versus lowest categories of poultry intake, a significantly reduced risk of 14% for total stroke among US people [RR = 0.86, 95% CI = 0.77-0.95, I2 = 0.0%, p = 0.38].

The investigators found in subgroup analysis for the highest versus lowest categories of poultry intake, a significantly reduced risk of 17% for total stroke among women [RR = 0.83, 95% CI = 0.72-0.93, I2 = 0.0%, p = 0.63].

The investigators found in subgroup analysis no association between the highest poultry intake and ischemic stroke risk [RR = 0.91, 95% CI = 0.79-1.02, I2 = 0.0%, p = 0.93].

The investigators found in subgroup analysis no association between the highest poultry intake and hemorrhagic stroke risk [RR = 0.82, 95% CI = 0.59-1.04, I2 = 20.5%, p = 0.28].

The investigators found one serving per week increment in poultry intake was not associated with the risk of stroke [RR = 1.00, 95% CI = 0.96-1.03, I2 = 69.0%, p = 0.004].

The investigators found nonlinear dose-response meta-analysis showed a lower risk of stroke at consumption of 1 serving/week.  

The investigators concluded that 1 serving/week poultry intake reduces risk of stroke, particularly among US people and women.

Original title:
Dietary poultry intake and the risk of stroke: A dose-response meta-analysis of prospective cohort studies by Mohammadi H, Jayedi A, […], Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29460808

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1 serving poultry corresponds to 100 gram raw poultry.
This meal provides 75 grams of poultry.
Poultry are chickens, turkeys, geese and ducks.

Objectives:
Dairy product consumption may affect the risk of hip fracture, but previous studies have reported inconsistent findings. Therefore, this review article has been conducted.

Does consumption of dairy products reduce risk of hip fracture?

Study design:
This review article included 10 cohort studies (with a total of 8,613 hip fracture events and 363,557 participants. The length of follow-up ranged from 3 to 22 years) and 8 case-control studies (3,815 hip fracture cases and 6,415 controls/subjects without hip fracture).

Results and conclusions:
The investigators found in cohort studies no association between a high milk consumption and hip fracture risk [pooled RR = 0.91, 95% CI = 0.74-1.12, I2 = 75.0%, p  0.01].
There were no significant changes to the results after using the trim-and-fill method when including 4 missing articles [adjusted random effects summary RR = 1.06, 95% CI = 0.91-1.23].

The investigators found, however, case-control studies indicated that participants in the highest categories of milk consumption had a 29% reduction in the risk of hip fracture [OR = 0.71, 95% CI = 0.55-0.91, I2 = 54%, p = 0.04].
There were no significant changes to the results after using the trim-and-fill method when including 1 missing article [adjusted random effects summary OR = 0.74, 95% CI = 0.57-0.97].

The investigators found in cohort studies no association between a high total dairy consumption and hip fracture risk [pooled RR = 1.02, 95% CI = 0.93-1.12]. No association because RR of 1 was found in the 95% CI of 0.93 to 1.12. RR of 1 means no risk/association.

The investigators found cohort studies indicated that participants in the highest categories of yoghurt consumption had a 25% reduction in the risk of hip fracture [RR = 0.75, 95% CI = 0.66-0.86].
 

The investigators found cohort studies indicated that participants in the highest categories of cheese consumption had a 32% reduction in the risk of hip fracture [RR = 0.68, 95% CI = 0.61-0.77].

The investigators found the summary RR for an increased milk consumption of 200 g/day was 1.00 [95% CI = 0.94-1.07, I2 = 87%, p heterogeneity  0.01] among cohort studies.

The investigators found in cohort studies there was a nonlinear positive association between milk consumption and hip fracture risk [p nonlinearity  0.01], with a rapid increase in risk when milk consumption increased from 0 to 600 g/d. However, there was no further increase in risk with milk consumption between 600 and 1200 g/d.

The investigators found in case-control studies there was a nonlinear association between milk consumption and hip fracture risk [p nonlinearity = 0.28], with a reduction in risk with milk consumption of 200-600 g/d. However, the confidence intervals were wide for all outcomes.

The investigators concluded that a high consumption of yogurt and cheese is associated with a lower risk of hip fracture in cohort studies.

Original title:
Dairy product consumption and risk of hip fracture: a systematic review and meta-analysis by Bian S, Hu J, [...], Ma J.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5778815/

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Objectives:
New studies indicate that resveratrol can significantly reduce plasma lipids, but the result of randomized clinical trials (RCTs) on resveratrol effect and the serum lipid profile are contradictory. Therefore, this review article (meta-analysis) has been conducted.  

Do resveratrol supplements reduce plasma lipids, like cholesterol levels?

Study design:
This review article included 21 RCTs.

Results and conclusions:
The investigators found resveratrol supplements had no significant effects on both:
-total cholesterol (TC) [WMD = 0.08 mmol/L, 95% CI = -0.23 to 0.08, p = 0.349, I2 = 87.8%];
-low-density lipoprotein (LDL-C or bad cholesterol) [WMD = -0.04 mmol/L, 95% CI = -0.21 to 0.12, p  = 0.620, I2 = 93.4%] and;
-high density lipoprotein (HDL-C or good cholesterol) [WMD = -0.01 mmol/L, 95% CI = -0.04 to 0.02, p = 0.269, I2 = 88.6%].

The investigators found resveratrol supplements had significant effects on
triacylglycerol (TG) [WMD = 0.58 mmol/L, 95% CI = 0.34 to 0.82, p 0.0001, I2 = 99.8%]. But after removing 1 study the significance was eliminated.

The investigators also found that sex, age, BMI, resveratrol dosage and intervention duration could not change the results.

The investigators concluded that resveratrol supplements do not change lipid profile concentration, like cholesterol levels. Confirmation of this conclusion will require more studies exclusively on dyslipidemic patients in which the intake of lipid lowering agents is among the exclusion criteria.

Original title:
Effect of resveratrol on lipid profile: An updated systematic review and meta-analysis on randomized clinical trials by Haghighatdoost F and Hariri M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29305228

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Objectives:
Does the consumption of various types of tomato products reduce prostate cancer risk and is there a potential dose-response relationship?

Study design:
This review article included 30 studies, which summarized data from 24,222 cases (subjects with prostate cancer) among 260,461 participants.

Results and conclusions:
The investigators found that higher total tomato consumption was associated with a reduced risk of 19% for prostate cancer [RR = 0.81, 95% CI = 0.71 to 0.92, p = 0.001].

The investigators found in subgroup analysis that higher tomato foods consumption was associated with a reduced risk of 16% for prostate cancer [RR = 0.84, 95% CI = 0.72 to 0.98, p = 0.030].

The investigators found in subgroup analysis that higher cooked tomatoes and sauces consumption was associated with a reduced risk of 16% for prostate cancer [RR = 0.84, 95% CI = 0.73 to 0.98, p = 0.029]. 

The investigators found in subgroup analysis, however, no association between higher raw tomatoes consumption and prostate cancer risk [RR = 0.96, 95% CI = 0.84 to 1.09, p = 0.487].

The investigators found there was a significant dose-response association for total tomato consumption [p = 0.040], cooked tomatoes and sauces [p  0.001] and raw tomatoes [p = 0.037], but there was not a significant association with tomato foods [p-linear = 0.511, p-nonlinear = 0.289].

The investigators concluded that increased tomato consumption, particularly cooked tomatoes and sauces reduces prostate cancer risk. Furthermore, there are dose-response relationships for total tomato consumption and for cooked tomatoes and sauces. Further studies are required to determine the underlying mechanisms of these associations.

Original title:
Processed and raw tomato consumption and risk of prostate cancer: a systematic review and dose-response meta-analysis by Rowles JL, Ranard KM, […], Erdman JW Jr.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29317772

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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

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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

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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

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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.