The study proposed no association between headache and the results of Lactose Breath Test (LBT). However, it was observed that the majority of patients undergoing a LBT complained of headache and the rate dramatically increased among the patients who usually suffer from headache.

Lactose malabsorption (LM) is the incomplete absorption of lactose by enterocytes, mainly due to lactase deficiency on the brush border. The primary form of LM is genetically determined by polymorphisms of LCT gene located on chromosome 2 and it is widespread with different features in several ethnic groups. When incompletely digested and absorbed, lactose may be fermented by the gut microflora leading to an increased production of gases. On the other hand, the undigested lactose has an osmotic potential capable of attracting water into the intestinal lumen. While generally well-tolerated, in a certain rate of lactose malabsorbers, these mechanisms may generate a group of symptoms (diarrhoea, abdominal pain, bloating, and flatulence) characterizing the so-called lactose intolerance (LI). Nowadays, LBT is the best tool to diagnose lactose malabsorption, since it combines good accuracy and low costs. Migraine headache is characterized by intense throbbing or a pulsing sensation in one area of the head and is commonly accompanied by other symptoms such as nausea, vomiting, and extreme sensitivity to light and sound. It is known that food intolerance can be a trigger factor for many migraineurs. For some people, intolerances are easy to recognize; they know that if they eat a specific food, even if it is a small amount, a migraine attack will follow within a given period of time. However, for most people it is more complicated as the intolerance may be disguised and may sometimes only produce mild symptoms, or they may have several different intolerances.

Rationale behind research:

Data about the association between suspected lactose intolerance and headache is lacking. So, this perspective observational study was conducted to investigate the association between lactose intolerance and headache.

Objective:

To investigate the onset and severity of headache through a Visual Analog Scale during a standard LBT.

Study outcomes

• Headache: Patients were asked to report on a 100 mm-VAS

             Intensities of usual headache

             Headache prior to 25 g lactose administration

             Highest headache peak reached during LBT

             A positive differential VAS peak of >10 mm was considered significant

• Lactose Malabsorption: LBT was performed after an overnight fasting. Patients were asked to have a carbohydrate-restricted dinner on the day before the test and fast for at least 12 h to minimize basal H2 excretion. Exhaled air was collected with two-bag system, consisting of a mouthpiece, a T-valve and two collapsible bags (the first one collects alveolar air), at baseline and every 30 minutes for 4 hours after 25 g lactose assumption. Samples were analyzed immediately for H2 and CH4 with a Breath Tracker Quintron Gas Chromatograph. Results were expressed as p.p.m.

An increase in H2 >20 ppm within the fourth hour was indicative of lactose malabsorption.

Baseline: At baseline prior to test execution, patients in the two groups had reported similar mean headache intensities.

Outcomes

• Sixty-seven out of 93 (72%) of the examined population showed to be lactose malabsorbers. Within the group of 67 lactose malabsorbers, 50.7% showed a significant increase in headache VAS during the test; meanwhile in 26 pts non-malabsorbers, 57.7% showed a significant increase in headache VAS during the test, without a significant difference in two groups (p=0.36).
• In 41 patients usually suffering from headache (mean habitual of VAS 65.1 ± 18.3 mm) onset a significant worsening of headache with a mean increase of 33.5 ± 28.9 from a baseline of 6.3 ± 2.7 mm. Meanwhile, 52 patients who usually not suffering from headache (mean habitual VAS 6.8 ± 4.1 mm) onset a mean increase of 15.4 ± 7.5 mm from 5.3 ± 3.5 mm baseline value p=0,003).

Figure 1: Mean increase value of headache in patients usually suffering from headache compared to non-usually suffering

• No significant correlations were observed between the VAS increase and H2 nor CH4 excretion peaks.
  

In this study, we did not found any correlation between headache and the result of LBT. Although, we observed that majority of patients undergoing LBT complained of headache and the rate dramatically increased among the patients who usually suffer from headache.

In a similar study conducted on almost 2000 people, the authors found that about 5% patients complain of fatigue and up to 10% patients complain of headache after the lactose test, irrespective whether the test was positive or negative. Hence, they supposed that the accumulation of toxic substances may be responsible for these symptoms. The present study denies the existence of an association between lactose malabsorption and headache; though we found that headache significantly worsened in patients usually suffering from headache, regardless lactose absorption. The study could not assess whether it happened because of lactose administration for testing purposes or not, since some strong confounders should be ruled out, first of all the prolonged fasting in a population with an unestablished risk of hypoglycemia.