For example, those who follow vegan or vegetarian diets or are over the age of 60 may need supplementation (Pawlak, 2014
Beginning at 300mcg allows assessment of response without overshooting the necessary dose
Depending on the severity of the symptoms, a hangover can be mild (with a slight headache and fatigue or just general discomfort), moderate (moderate-to-severe headache, nausea, vomiting, irritability, fatigue, and dehydration),or severe (intense and severe headache, mood swings, anxiety, dizziness, severe nausea and vomiting, impaired concentration, muscle pain, extreme weakness, and fatigue)
Acceptable as long as you feel well when you come to donate, and your blood pressure is at least 90/50 (systolic/diastolic)