Abstract

Submariners are a group of employees who are occupationally deprived of sunlight.

Cholesterol is the precursor of Vitamin D, which is generated, in part, by Ultraviolet (UV)

induced photosynthesis. With an absence of UV light, a diet devoid of fresh fruit and

vegetables and limited opportunities for exercise for periods of up to six months, it was

perceived that this occupational group would be at higher risk of dyslipidaemia due to excess

Cholesterol as this would not be used to generate Vitamin D. The aim of this thesis was to

investigate the relationship between Vitamin D and dyslipidaemia in Royal Navy

Submariners.

Submariners from four Royal Navy Submarines participated. These units consisted of a

submarine alongside for maintenance in Scotland in summer, one submarine deployed in

winter, one in summer and one in the Mediterranean Sea. Dietary intake data, including

supplements, were obtained using a bespoke and validated questionnaire along with

measures of changes in anthropometric status and physical fitness. Fasted serum lipid and

Vitamin D (as assessed from serum 25-hydroxyvitamin D (25(OH)D)) concentrations) were

obtained at the start and end of each study period (typically the beginning and end of

deployment).

The studies demonstrated that submarine deployments have an acute lowering effect on the

serum lipid profile, which was partly explained by changes in non-lean body mass. This

effect contrasts with a non-deployed similar population where both body mass and blood

lipid profile were increased. Muscular strength, as assessed by grip dynamometer and static

lift, was maintained or improved during each study period. Serum Vitamin D declined in

those who did not consume supplements, and this was especially marked in those

undertaking a winter patrol. It is concluded that submarine deployments have a beneficial

effect on serum lipid levels however Vitamin D supplementation is required to conserve bone

health.