Vitamin C (ascorbic acid) is a well-known antioxidant that is involved in anxiety, stress, depression, fatigue and mood state in humans . The purpose of this study is to investigate the effect of low doses of vitamin C on decreasing the level of public speaking stress in term of salivary cortisol , blood pressure (systolic and diastolic) and heart rate . A purposive sample of (90) were included in this randomized placeboled trial study (60 students were given 500 mg of vitamin c per day for one week a group presentation while 30 other students were given placebo for one week before a group presentation) . Salivary cortisol was measured by means of commercial immunoenzymatic kits . Blood pressure (systolic and diastolic) and heart rate were measured immediately before and after presentation .

Experimental randomized placebo trial study approach was designed to meet the previously mentioned objectives of the current study. The period of the study is from 1st November 2018 to 20th April 2019. A random sample of (90) students was taken in this study .

The students were divided in to two groups :-

1. Study Group :- included 60 students given vitamin C ( 500 mg per day) for one week before presentation .
2. Placebo :- included 30 students given placebo for one week before presentation. Exclusion criteria included : chronic diseases (DM , hypertension), hormonal disturbances, psychotic disorders, kidney stones and anemia . Students that have previous experience of public speaking were also excluded .

Participants were asked to rinse their mouth with water before collecting saliva. A minimum volume of 1 mL saliva was obtained directly by expectorating into a collecting tube. Food and beverages such as tea, soft drinks, and coffee were not permitted 30 minutes prior to any sample collection. Because salivary cortisol concentration is independent of flow rate and sugarless gum does not interfere with the salivary assay, 21 participants were permitted to chew sugarless gum if needed to stimulate saliva flow. Participants were also instructed not to brush their teeth 30 minutes before saliva collection and to refrain from wearing lipstick on the day of saliva collection (Hellhammer et al., 1987) .

Inclusion Criteria:

- students have a presentation

Exclusion Criteria:

- Exclusion criteria included : chronic diseases (DM , hypertension), hormonal disturbances, psychotic disorders, kidney stones and anemia . Students that have previous experience of public speaking were also excluded .