Iron deficiency is the most prevalent nutritional deficiency worldwide with one in four estimated to be affected by iron deficiency anaemia. Women of reproductive age are at greatest risk for iron deficiency and anaemia due to iron losses during menstruation and childbirth as well as the increased need for iron throughout pregnancy. However, iron deficiency without anaemia is at least twice as common as iron deficiency anaemia with females aged 11-49 at the biggest risk of all. Despite this, it is commonly left undiagnosed. Those who are iron deficient non-anaemic can still suffer from the same common consequences of iron deficiency anaemia; these include unexplained fatigue, mood changes and decreased cognitive performance. Previous studies have found a significant relationship between iron status and cognitive performance in anaemic women. However, studies assessing cognition, mood and fatigue in women of varying iron status including those who are iron deficient nonanaemic are lacking. The most recent observational study of this kind found that better iron status was associated with better sustained attention but worse working memory. However, iron deficient anaemic females were not included in this observation. This study will extend upon this in order to determine any differences between non-anaemic iron deficiency and iron deficiency anaemia. The aims of this study are to improve knowledge concerning women's health and to determine whether there is a relationship between iron status, cognitive performance, subjective mood and fatigue in women of reproductive age (18-49 years).

Each participant will be required to attend the laboratory on two occasions. The first is comprised of a screening/training visit, which will take place in the afternoon for approximately 2.5 hours. This will also be between days 21-28/the week before onset of their menstrual cycle. If they do not have menstrual bleeds then this appointment can be any afternoon. This will comprise: briefing of requirements of the study; obtaining of informed consent; confirmation of eligibility to take part, including collection of demographic data and health screening, and training on the cognitive and mood measures. The training session will follow standard operating procedures to decrease the chance of learning effects during main trials. Extra training will be given where necessary.

Participants will be required to complete questionnaires based upon food frequency, caffeine consumption and to estimate the number of hours of exercise completed on a weekly basis. A menstrual cycle questionnaire will also be completed to estimate menstrual blood loss and so that participants attend their testing visit during days 7-14 of their cycle. If participants do not have a menstrual cycle due to contraceptive methods, then appointments will be approximately two weeks apart.

A finger-prick and venous blood sample will be collected from participants, which will be analysed for iron status. Those whose haemoglobin levels are <120g/L will be advised to seek advice from their GP.

For the testing visit, participants will be asked to fast for 12 hours prior to the visit, avoiding intake of all food and drink with the exception of water. They will also be asked to avoid alcohol and refrain from intake of 'over the counter' medication for 24 hours. Participants will arrive at the laboratory at a designated time in the morning. The following procedures will take place prior to cognitive and mood testing:

• Review of continued conformity to eligibility criteria
• Adverse event and concomitant medication assessment
• Ensure that participant is in good health

Participants will then complete the baseline cognitive and mood assessments.

Inclusion Criteria:

• Healthy
• Female
• Aged 18-49 (inclusive)
• Have a BMI of between 18.5-40
• Have an English bank account (required for payment)

Exclusion Criteria:

• Aged under 18 or over 49
• BMI lower than 18.5 or higher than 40
• Pre-existing medical condition/illness with some exceptions - please check with researcher
• Blood disorders (excluding anaemia) or any known active infections
• Current or past breast cancer diagnosis and/or mastectomy
• Smoking or use of any nicotine replacement products e.g. vaping, gum, patches
• Pregnant, trying to get pregnant or breast feeding
• Currently taking any prescription medication with some exceptions - please check with researcher
• Regular use of dietary/herbal supplements within the last month (defined as more than 3 consecutive days or 4 days in total)
• Use of iron supplements within the past 4 months
• Have donated more than 300ml of blood in the past 3 months
• History of significant head trauma or suffer from frequent migraines that require medication (more than or equal to one per month)
• Learning difficulties, dyslexia, or colour blindness
• Visual impairment that cannot be corrected with glasses or contact lenses
• Currently taking part in any other clinical or nutritional intervention studies or have in the past 4 weeks
• Any health condition that would prevent fulfillment of the study requirements

Must be female at birth

Females aged 18-49 who meet the inclusion criteria who are based in Newcastle-upon-Tyne, United Kingdom and the residing North-East area.