Exposure to heat stress can compromise the physiological and cognitive function and be life threatening, particularly in a military setting. Various strategies of precondition to heat stress that have been explored in the past proved to be inapplicable. We aim to examine the influences of Astaxanthin supplementation as a preconditioning strategy to heat stress in a human model using a heat tolerance test. This will be achieved by a double-blind, placebo controlled supplementation trial, exposing human subjects, before and after consuming Astaxanthin or a placebo, to a controlled heat strain environment, while performing moderate exercise in a heated chamber.

34 young, healthy civilian volunteers will participate in this study. After reading and signing an informed consent form, all subjects will undergo medical examination and an interview with a nutritionist to assess their dietary intake of Astaxanthin. They will then undergo 3 days of training on the cognitive testing software.

During the first stage, while consuming an Astaxanthin free diet, the subjects will participate in the physiological tests:heat tolerance test (HTT), thermo-neutral test (TTT) and maximal oxygen consumption test (VO2max) on 3 separate days.

During the second stage, the subjects will be randomly and blindly assigned to either the placebo or the Astaxanthin supplementation arms, and undergo 35-40 days of supplementation.

Physiological testing of the second stage will take place between the 31st and 35th (up to 40th - optional) days of supplementation and will include HTT, TTT and VO2max on 3 separate days.

Inclusion Criteria:

• Healthy civilian volunteers.
• Aged 20-30 years.
• Without known medical illness or medication use.

Exclusion Criteria:

• The existence or suspicion of existing cardiac or respiratory disease.
• Hypertension.
• Diabetes.
• Any hormonal disease or any other chronic illness that may inhibit participation in the experiment.
• Infectious disease 3 days prior to the experiment.