Objectives:
Studies have reminded that cardiovascular metabolic comorbidities made patients more susceptible to suffer 2019 novel corona virus (2019-nCoV) disease (COVID-19) and exacerbated the infection. Therefore, this review article has been conducted.

Have patients with cardiovascular metabolic diseases an increased risk of getting a corona virus (COVID-19) infection?

Study design:
This review article included 6 studies with 1,527 patients.

Objectives:
Current evidence on associations between intakes of linoleic acid (LA), the predominant n-6 (ω-6) fatty acid and mortality is inconsistent and has not been summarized by a systematic review and meta-analysis. Therefore, this review article has been conducted.

Does higher linoleic acid intake, assessed by dietary surveys or biomarkers decrease mortality from all causes, cardiovascular disease (CVD) and cancer?

Objectives:
The relationship between maternal folic acid supplementation in pregnancy and infant birth weight has not been well described in low- and middle-income countries. Therefore, this review article has been conducted.

Does maternal folic acid supplementation in pregnancy increase infant birth weight in low- and middle-income countries?

Study design:
This review article included 13 cohort studies and 4 randomized controlled trials (4 RCTs) with a total of  275,421 pregnant women.

Objectives:
Several epidemiological studies have been performed to evaluate the association of dietary intake of vitamin C-oriented foods (DIVCF) with risk of fracture and bone mineral density (BMD) loss, but the results remain controversial. Therefore, this review article has been conducted.

Does dietary intake of vitamin C-oriented foods decrease risk of fracture and bone mineral density loss?

Objectives:
Does post-diagnosis dietary supplement use decrease total mortality, cancer mortality and recurrence among cancer survivors?

Study design:
This review article included observational studies and randomized clinical trials (RCT).

Results and conclusions:
The investigators found in 4 observational studies, compared to no supplementation, calcium supplementation significantly reduced total mortality with 12% [RR = 0.88, 95% CI = 0.77 to 1.00, I2 = 0%] among all cancer survivors.

Objectives:
Omega-3 fatty acid and vitamin E or D co-supplementation may be an important approach to improve metabolic status in gestational diabetes, but the results are conflicting. Therefore, this review article has been conducted.

Do omega-3 fatty acid and vitamin E or D co-supplementation improve metabolic status in gestational diabetes?

Study design:
This review article included 4 RCTs.

Objectives:
Does hepatitis C virus (HCV) infection increase risk of pancreatic cancer (PAC)?

Study design:
This review article included 8 cohort and 8 case-control studies.

Objectives:
Does flaxseed supplementation decrease plasma lipoprotein(a) levels?

Study design:
This review article included 7 RCTs with 629 individuals.

Results and conclusions:
The investigators found flaxseed supplementation significantly reduced plasma lipoprotein(a) levels [MD = -2.06 mg/dL, 95% CI = -3.846 to -0.274, p = 0.024, I2 = 0%, p = 0.986].

Objectives:
Which types of exercise training (whole body vibration training, aerobic training, strength training and combined training) increase lumbar spine and femoral neck bone mineral density (BMD) in older postmenopausal women (PMW)?

Study design:
This review article included 16 RCTs with 1,624 subjects.

Results and conclusions:
The investigators found no significant change in lumbar spine bone mineral density following exercise training [MD = 0.01 g/cm², 95% CI = -0.01 to 0.02].

Objectives:
Previous studies had been published to explore the association about carbohydrate intake on esophageal cancer risk, with inconsistent results. Therefore, this review article (meta-analysis) has been conducted.