Other things to keep in mind:
Some runners may experience issues related to distance running such as gastrointestinal upset on heavy training days. Waiting several hours after eating before training may help to reduce gastrointestinal discomfort. A meal that is low in fibre and fat or a liquid meal replacement may be better tolerated.
Female distance runners are at higher risk of low iron levels due to menstruation. Iron rich foods include red meat, poultry, salmon, legumes, nuts, dried apricots, whole grains and green leafy vegetables. Eating foods high in vitamin C (fruit and vegetables) simultaneously will improve iron absorption from food. Conversely coffee, tea, red wine and tofu can reduce iron absorption. Low iron levels reduce the body’s ability to carry oxygen and will result in early fatigue and poor overall performance and should be investigated by a GP.