Gastric acid secretion rate and buffer content of the stomach after a rice- and a wheat-based meal in normal subjects and patients with duodenal ulcer

Food buffering capacity: quantification methods and its importance in digestion and health

Understanding the influence of food properties on buffering capacity will have an impact on gastric secretions and breakdown during digestion.

Bioavailability of Vitamin B12 from Dairy Products Using a Pig Model

The present study compares the bioavailability of vitamin B₁₂ (B₁₂) of dairy products or synthetic B₁₂, using the pig as an experimental model for humans. Eleven pigs were used in a cross-over design to assess the net portal drained viscera (PDV) flux of blood plasma B₁₂ after ingestion of tofu (TF; devoid of B₁₂), Swiss cheese (SC), Cheddar cheese (CC), yogurt (YG), and synthetic B₁₂ (TB₁₂; TF supplemented with cyanocobalamin), providing a total of 25 µg of B₁₂ each. PDV blood plasma flow for SC and CC were higher than for TF and TB₁₂ (p ≤ 0.04) whereas YG was higher than TF (p = 0.05). Porto-arterial difference of blood plasma B₁₂ concentrations were higher for CC and TB₁₂ than for TF and YG (p ≤ 0.04) but not different from SC (p ≥ 0.15). Net PDV flux of B₁₂ was only different from zero for CC. However, the net PDV flux of B₁₂ for CC was not different from SC or TB₁₂. Cumulative net PDV flux of B₁₂ for SC, TB₁₂, and CC were 2.9, 4.4, and 8.3 µg 23 h post-meal, corresponding to a bioavailability of 11.6%, 17.5%, and 33.0%, respectively. In conclusion, CC had the best bioavailability of B₁₂ among the tested dairy products or compared to synthetic B₁₂.

Circadian pattern of intragastric acidity in duodenal ulcer patients: a study of variations in relation to ulcer activity

The relation between intragastric acidity and duodenal ulcer activity was studied prospectively in 21 patients with endoscopically proved duodenal ulcers. The 24 hour intragastric acidity was measured on four separate occasions by continuous recording using combined glass electrodes: (a) in the presence of an ulcer crater without treatment; (b) during active ulceration being treated with ranitidine; (c) during early healing after a six week course of ranitidine; (d) during late healing six months after acute ulceration. Intragastric acidity was also monitored in 20 healthy subjects. At all stages of ulcer activity and during all predefined time periods, duodenal ulcer patients had significantly higher gastric acidity than healthy control subjects. Duodenal ulcer patients showed a similar circadian pattern of intragastric acidity during exacerbation of ulcer disease and in remission during the early and late ulcer healing periods. These results argue against a direct relation between the activity of duodenal ulcer disease and gastric acidity. It is concluded that the chronic recurrent course of duodenal ulcer disease does not result from a fluctuation in intragastric acidity.

Reducing meal-stimulated acid secretion versus reducing nocturnal acid secretion for healing of duodenal ulcer

Both meal-stimulated and nocturnal acid secretions have been shown to be abnormally increased in patients with duodenal ulcer. The relative efficacy of an acid-reducing regimen aimed specifically at controlling postprandial acid secretion compared with one that controls nocturnal acid secretion is, however, not known. The endoscopic healing rates at weeks 2, 4, 6, 8, 10, and 12 of three cimetidine regimens with identical total daily dose--bedtime (1200 mg), mealtime (400 mg three times a day with meals), and reference (200 mg three times a day with meals and 600 mg at bedtime)--were compared in a randomized study on 141 patients with endoscopically proven duodenal ulcer. Evaluating endoscopists were blinded to patients' form and duration of treatment and their clinical progress; patients were unaware of the comparative design of the study. Life-table analysis for the 12 weeks of observation revealed that the mealtime regimen resulted in significantly (P less than 0.05) better healing rates than either the bedtime or the reference regimen. The differences were accounted for largely by the significantly (P less than 0.04) better healing rate at two weeks with the mealtime regimen (68%) than with either the bedtime (47%) or the reference (45%) regimen. These findings indicate that a regimen that aims at controlling meal-stimulated acid secretion achieves a faster healing rate than one that aims at controlling nocturnal acid secretion in the treatment of duodenal ulcer, and they suggest that postprandial acid secretion plays a greater role than nocturnal acid secretion in the pathophysiology of this condition.

24-hour study of intragastric acidity in duodenal ulcer patients and normal subjects using continuous intraluminal pH-metry

The circadian pattern of intragastric acidity was assessed in 19 healthy subjects and 37 patients with active, endoscopically proven duodenal ulcer using 24-hr continuous intraluminal pH-metry. The median pH 24-hr profiles showed that ulcer patients had lower postprandial pH elevations and a smaller decline in acidity during the early morning hours when compared with controls. The after-lunch and -dinner area under the curve and maximum pH values were significantly higher in controls compared to ulcer patients. In the nighttime, the median pH values in controls were significantly higher during 9 PM to 12 PM (P = 0.02), 12 PM to 4 AM (P = 0.01), and 4 AM to 8 AM (P = 0.0008) compared to the ulcer patients. We conclude that the 24-hr acidity is higher in ulcer patients compared to healthy subjects and that the differences are particularly evident in the postprandial and nocturnal periods.

Detailed comparison of basal and food-stimulated gastric acid secretion rates and serum gastrin concentrations in duodenal ulcer patients and normal subjects

We measured basal and peak acid outputs, food-stimulated acid secretion, and basal and food-stimulated serum gastrin concentrations in a large group of duodenal ulcer patients and normal subjects. Basal and peak acid outputs were significantly higher in ulcer patients. In contrast, acid secretion was similar in the groups when food was infused into the stomach and when sham feeding was combined with meal infusion to simulate normal eating. Meal-stimulated acid secretion, expressed as a percentage of peak acid output to correct for differences in secretory capacity, was lower in ulcer patients (P less than 0.002). Basal serum gastrin concentrations were higher in ulcer patients, which may have contributed to higher basal acid output. However, increases in serum gastrin after food were similar in the groups. Duodenal ulcer patients, as a group, have increased basal and maximal acid secretion, but the amount of acid secreted and gastrin released after eating is normal.

The effect of dietary fibre isolates on gastric secretion, acidity and emptying

1. In six volunteers, the effect of intragastric administration of different water-soluble chemical isolates of dietary fibre on gastric secretion, acidity and emptying was studied. 2. At 30 min after administration of the test meals, the stomach contents were completely aspirated and the volume, pH, phenol red concentration, total titratable acidity and different electrolytes were measured. 3. Compared with the control meal, the pH and unionized (combined) hydrogen concentrations were significantly higher (P less than 0.05) following most of the fibre-containing meals, while the total titratable acid concentration was not significantly different. None of the fibre-containing meals appreciably altered the volume or type of gastric secretion but had a low-grade variable effect on gastric emptying. 4. It is concluded that most dietary fibre isolates, although having a definite and notable buffering effect on the acid in the stomach, have a minimal effect on gastric secretion and a variable and small effect on gastric emptying.

Mastication and acid secretion

The gastric acid response and the buffer capacity of the stomach were measured in 30 control subjects and 22 duodenal ulcer patients in response to a masticatory (solid) and a non-masticatory (homogenized) meal having the same chemical composition. The peak acid output values were equal after a masticatory and after a non-masticatory diet in control subjects (masticatory 18.1 +/- 1.2, non-masticatory 15.7 +/- 1.3 mmol/hr) as well as in duodenal ulcer patients (masticatory 35.7 +/- 1.5, non-masticatory 33.7 +/- 1.1 mmol/hr). The buffer capacity of the stomach contents 1 hr after the meal was significantly greater after a masticatory diet than a non-masticatory diet in both controls (14.6 +/- 1.4 and 9.0 +/- 1.9 mmol) and in duodenal ulcer patients (9.5 +/- 1.5 and 7.5 +/- 1.2 mmol). Duodenal ulcer patients had a significantly lower buffer capacity compared with controls. Masticatory diets may play a part in protecting individuals from developing duodenal ulcer.