B-vitamins, genotype and disease causality

Abstract

Despite a great deal of research effort there is still considerable uncertainty surrounding the importance of the B-vitamins in health and disease. This continuing uncertainty is partly a result of the difficulty of measuring intake, confounding in observational studies and the very large numbers required to evaluate primary prevention in randomised controlled trials. Consequently, genetic data are increasingly being used to infer nutritional effects on health and even in the formulation of nutrition policy using the approach of ‘mendelian randomisation’. Genetic information has already contributed greatly to the understanding of B-vitamin metabolism and the heterogeneity of responses to intake. It has the potential to provide further nutritional insights and to assist in the elucidation of causal mechanisms, but it is important that genetic data is not viewed as an alternative to nutritional information, both are necessary when addressing nutritional problems. Similarly, the interpretation of nutrient and biomarker status in some experimental designs may require knowledge of genotype. Formal tests of gene–gene and gene–nutrient interaction are of limited value in nutritional studies and the formulation of policy. Graphical representation of diet–genotype–health data greatly assists in the elucidation of the nature of genetic effects, their interaction with nutrition and the implications for nutrition policy.

Transcriptomics and functional genetic polymorphisms as biomarkers of micronutrient function: focus on selenium as an exemplar

“…In addition to deficiency-associated diseases, there is concern with regard to the disease risks associated with sub-optimal intakes as low intake of certain micronutrients has been implicated in multi-factorial diseases such as cancer, heart disease and cognitive decline, especially in the elderly when food intakes fall and micronutrient intake can become critical (1)(2)(3) . However, despite some evidence suggesting the possible benefits of increased intake of micronutrients such as folate, selenium (Se), carotenoids, vitamin B 12 and vitamin D, for some micronutrients the benefits of supplementation have not been proven and indeed in some cases there is evidence that raising intake by supplementation may increase disease risk. For example, there is controversy over whether mandatory folate fortification of flour in the USA has been associated with increased cancer rates (4)(5)(6) .…”

The challenges for molecular nutrition research 1: linking genotype to healthy nutrition

“…Nutrition can give clues of how to increase functional relevance. Focussing on SNPs that are on functional pathways in terms of known nutritionally-relevant metabolism, and on coherent metabolic pathways, may allow a ''causal pathway'' approach to the interaction of nutritional factors and multiple genetic variations [22]. Metabolomics may also be able to distinguish between ''contingent'' dietrelated parameters (e.g.…”

Effects of Vitamin B12 Deficiency on Ejaculation Time in Patients with Chronic Gastritis

“…We know in the light of recent genetic studies that vit B12 levels are affected by single nucleotide polymorphisms in multiple genes. Genetic variants can alter tissue levels of vit B12 by affecting the proteins involved in certain stages of absorption, cellular intake, and intracellular metabolism (44). Investigating the genetic factors will allow for more objective evaluation of vit B12 levels.…”