Table 2

 Systemic lactose intolerance compared with Darwin’s disease

Symptoms of systemic lactose intolerance% People with lactose intolerance who have this symptom*Darwin’s description of his symptomsOccurrence of Darwin’s symptoms
*Represents proportion of people diagnosed as lactose intolerant who have this particular symptom within 48 hours of taking lactose. Darwin’s occurrence is based on his notes and letters during periods of the episodes. The systemic symptoms of lactose intolerance are described previously.17,18
Gut symptoms (pain, bloating, diarrhoea)100Stomach acheCommon
Flatulence100Flatulence (belching)Common
Headache86HeadacheCommon
Light headedness and loss of concentration82Swimming head and difficulty to concentrateCommon
Nausea and vomiting78VomitingVery common
Muscle and joint pain71Rheumatic painOften
Tiredness and chronic fatigue63Chronic fatigue and exhaustionVery common
Allergy (eczema, hay fever, rhinitis, sinusitis)40Skin rash and boilsOften
Mouth ulcers30Mouth soresCommon
Heart palpitations24Palpitations in the chestCommon
DepressionCommon, but not quantifiedDepressionFrequent