Objectives:
Does higher lycopene exposure decrease risk of cardiovascular diseases (CVD)?

Study design:
This review article included 14 observational studies.
Subgroup analyses showed that retrospective and low quality studies were statistically significant sources of heterogeneity.

Objectives:
Red meat intake has been associated with risk of colorectal cancer, potentially mediated through heterocyclic amines. The metabolic efficiency of N-acetyltransferase 2 (NAT2) required for the metabolic activation of such amines is influenced by genetic variation. The interaction between red meat intake, NAT2 genotype and colorectal cancer has been inconsistently reported. Therefore, this review article has been conducted.

Is there an interaction between red meat intake, NAT2 genotype and colorectal cancer?

Objectives:
Randomised controlled trials (RCTs) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation. Therefore, this meta-analysis (systematic review) has been conducted.

Has vitamin C supplementation a favorable effect on circulating biomarkers of glycaemic and insulin regulation?

Study design:
This review article included 22 RCTs with 937 participants.

Objectives:
Is there an association of intake of different vitamins and multiple-vitamin supplements and the incidence of colorectal cancer?

Study design:
This review article included 47 articles (cohort studies).

There was unacceptable heterogeneity for studies of multiple-vitamin supplements, so findings were inconclusive.

Scientific studies (review articles) on the relationship between vitamin B2 and disease prevention:
A review article (a collection of scientific studies on a specific topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

Scientific studies on the relationship between vitamin B6 and disease prevention:
A review article (a collection of scientific studies on a specific topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

A review article (a collection of scientific studies on a specific topic) of cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

Objectives:
Controversy persists regarding the effect of mixtures of conjugated linoleic acids (c9,t11- and t12,c10-CLA) in fasting blood glucose (FBG) and waist circumference (WC) in humans. Therefore, this review article (meta-analysis) has been conducted.

Does CLA reduce fasting blood glucose (FBG) and waist circumference (WC) in humans?

Study design:
This review article included 32 randomized clinical trials.

Objectives:
Recent studies have found that the serum zinc levels were associated with the risk of Parkinson's disease (PD), but the results were inconsistent. Therefore, this meta-analysis (review article) has been conducted.

Is there an association between serum zinc levels and Parkinson's disease risk?

Study design:
This review article included 11 articles involving 822 Parkinson's disease patients and 777 healthy controls (subjects without Parkinson's disease).

No publication bias was found.

Potassium-rich meals (contains at least 1g potassium):

Objectives:
The aim of this review article was to assess the relation between the level of habitual potassium intake and the incidence of cardiovascular disease (CVD).