Selenium and Immune Function

Not Applicable

Completed

Conditions: Healthy

Interventions: Dietary Supplement: 50ug selenium enriched yeast
Other: Placebo
Dietary Supplement: Control onion
Dietary Supplement: 100ug selenium enriched yeast
Dietary Supplement: 200ug selenium enriched yeast
Dietary Supplement: Enriched onion

Registration Number: NCT00279812

Lead Sponsor: Quadram Institute Bioscience

Brief Summary: The aim of the study is to investigate the relationship between dose and form of selenium on immune function, and to identify functional markers of selenium status.

Detailed Description: One of the proposed consequences of marginal selenium status is impaired immune function. Establishing the potential role of selenium as an enhancer of immune response in vivo may provide evidence-base for public health policy, with important consequences for preventing influenza and similar diseases in the elderly.

The project consists of a placebo controlled selenium supplementation study and a dietary intervention with un-enriched and selenium enriched onions. In a parallel group design, subjects will be given either one of three doses of Selenomethionine (50, 100 or 200µg selenium/day) or a placebo per day or selenium enriched or un-enriched onions (in the form of test meals) for 12 weeks. Changes in the expression of Se-responsive genes and proteins in blood will be measured and compared with changes in plasma Se concentration and selected selenoproteins. The relationship between dietary Se intake and systemic and mucosal immune responses to influenza vaccine will be examined. Changes in immune cell populations and the influence of Se on NK and CD8 cytotoxicity will be determined by flow cytometry.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 133

Inclusion Criteria

Men and women, age 50-64
Plasma selenium level <1.2µmol/l (±10%)

Exclusion Criteria

Elevated blood pressure measurements (<90/50 or <95/50 if symptomatic or >160/100)
Body mass index (BMI) <18.5 or >35
Results of the clinical screening which are judged by the Human Nutrition Unit (HNU) Medical advisor to be indicative of a health problem and could compromise the well-being of the volunteer if they participated, or which would affect the data.
Smokers
Diagnosed with gastrointestinal disease (excluding hiatus hernia unless symptomatic or study intervention/procedure is contraindicated) for which they have been taking prescription drugs on a chronic basis.
Diagnosed with a long-term illness requiring active treatment, e.g. diabetes, cancer, cardiovascular disease.
On regularly prescribed medication known to have a profound effect on the immune function
Regularly using antacids and laxatives (at least once a week)
Sufferers of hay-fever taking regular steroid medication
Unwillingness to discontinue dietary (other than vitamins and minerals) or herbal supplements less than one month prior to the start of the study and for the duration of the study
Blood donation within 16 weeks of the first study sample and who intend to donate blood less than 16 weeks after the last study sample
Antibiotic use within four weeks prior to starting the study
Those who receive or plan to receive any other type of immunisation during the study period
Those who have received an immunisation within 6 months of the start of the study
Intention to go on holiday/trips for more than 2 weeks during the twelve week intervention
Those planning a holiday/trip that requires immunisation during the twelve week intervention period
Parallel participation in another research project which involves dietary intervention or sampling of biological fluids/materials
Allergic to eggs or egg products
Allergic to chicken protein
Allergic to the antibiotic Gentamicin
A history of Guillain-Barre syndrome

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
50ug selenium enriched yeast	50ug selenium enriched yeast	50ug/d selenium enriched yeast (containing 60% selenomethionine)
Placebo	Placebo	Placebo
Control onion	Control onion	3 meals/wk containing un-enriched onions equivalent to 4ug/d Se
100ug selenium enriched yeast	100ug selenium enriched yeast	100ug/d selenium enriched yeast (containing 60% selenomethionine)
200ug selenium enriched yeast	200ug selenium enriched yeast	200ug/d selenium enriched yeast (containing 60% selenomethionine)
Enriched onion	Enriched onion	3 meals/wk containing enriched onions equivalent to 50ug/d Se

Primary Outcome Measures

Name	Time	Method
Cellular and Humoral Immune Response	12 weeks	Total glutathione peroxidase 1 activity in platelets after supplementation

Secondary Outcome Measures

Name	Time	Method
Selenoproteins and Se-biomarkers	10 weeks	Plasma selenoprotein P after the supllementation
Selenium Status	10 weeks	Plasma selenium concentration after supplementation