Ginseng refers to the extract of any slow growing perennial plant with a fleshy root, deriving from the Panax genus of the Araliaceae family. Ginseng root has been used as an intervention for the treatment of diabetes (Sotaniemi, Haapakoski & Rautio, 1995), boosting cognitive function (Scholey et al., 2010) and improving mental health (Ellis & Reddy, 2002). The most commonly used ginseng is Panax ginseng (Asia) and Panax quinquefolius (America). Ginsensosides are considered the core phytochemical compounds that contribute to the alleged beneficial effects of ginseng. In particular, ginsenosides Rb1 and Rg1 have been isolated and investigated for effects on cognitive function (Shin et al., 2016).

Scholey et al. (2010) was one of the first studies to provide support for a beneficial cognitive effect from American ginseng (Cereboost™), with better performance on working memory in healthy young adults. Improvements were most profound for a single dose of 200 mg on working memory tasks, specifically immediate word recall and numeric working memory speed. Cereboost also increased self-rated calmness compared to placebo, suggesting ginseng can enhance aspects of mood. Similarly, Ossoukhova et al. (2015) compared a single 200mg dose to placebo to investigate whether beneficial cognitive effects extend to a middle-aged cohort. Here, Cereboost significantly improved performance on the Cognitive Drug Research (CDR) working memory factor, specifically improving spatial working memory at three hours post dose.

Further study is required to evaluate ginseng specific effects with a standardized extract of P. quinquefolius, such as Cereboost™ on healthy participants. Significant results will have implications for investigating the neurocognitive effects in other populations, such as those with cognitive and memory problems.

The study comprises of a familiarisation visit and then two test days. The test days are separated by a 2 week interval during which time participants will be asked to consume a daily capsule for 14 days which will contain either an American ginseng root extract (200 mg Cereboost and Maltodextrin) or an identical placebo that does not contain any of the active ingredient. Participants will be asked to restrict their intake of certain foods for 48 hours before test days and intake of alcohol and caffeinated drinks for 24 hours prior. All participants will be required to fast overnight prior to each of the study days. Participants may withdraw at any time without giving any reason. In addition, a participant will be withdrawn from the study if they request discontinuation, exhibit a serious adverse event to any component of the test product, the participant significantly violates the exclusion or inclusion criteria, an illness emerges and/or opinion is that withdrawal is appropriate.

An outline of each session is as follows:

1. Familiarisation/practice visit: Volunteers will attend the Nutritional Psychology unit at the University of Reading, where they will receive a detailed explanation on the study and will be asked to sign the informed consent form. Once consent has been given the inclusion/exclusion criteria will be checked and measures of age, height and weight will be taken. Participants will then be asked to fill out a food frequency questionnaire before completing training on the cognitive test battery. Participants will be given two food diaries, with each diary completed in the 48 hours before each test day to check habitual diet and ensure they followed low flavonoid protocol. Finally the PANAS - X will be administered to gain a measure of trait mood
2. Test visits: On arrival of their first test day, participants will be randomly assigned to treatment (200 mg Cereboost™) or placebo condition. Each study day will begin at 9am with breakfast before completion of the computerized test battery to establish baseline performance. Participants will then take their allocated intervention and will be tested on the cognitive and mood battery at 2, 4 and 6 hours after consumption. A standard light lunch will be provided between the 2hr and 4 hr test points. On test visit 2, participants will have completed a 14 day course of their intervention and will be tested at the same time points at test visit 1, again receiving the intervention directly after the baseline test battery. Finally the PANAS - X will be administered again to gain a measure of trait mood following the 2 week intervention.

The computerized cognitive battery will include tests which are known to be sensitive to nutritional manipulations (Lamport, 2012) and will last no more than 45 minutes.

Inclusion Criteria:

• healthy, between 18-30

Exclusion Criteria:

• Smoke
• Use medications that may affect the outcome
• Have any allergic reactions to ingredients in the capsules
• Have a BMI greater than or equal to 30
• Are vegetarian
• Taking any dietary supplements which they are unwilling to stop for the duration of the study
• Drink more than 2 alcoholic beverages per day on an average week
• Have participated in any other cognitive trials within the last month.

Double-blind