Experimental studies have clearly demonstrated both the indispensability in stress situations of amino acids, previously considered to be non-essential, and the importance of the specific properties of these same amino acids. Glutamine, arginine and their precursors/metabolites, ornithine and alpha-ketoglutarate, exert anabolic or anticatabolic effects through their involvement in protein metabolism, in the immune response and in cell proliferation. Clinical studies suggest that the supplementation of nutritional therapy with these amino acids can be of significant benefit for injured patients.

Amino acids with anabolic properties

In general, peptic ulcer occurs at equal rates in the East and the West but with marked regional differences in both, even within the same country. In the West, the incidence of peptic ulcer, particularly duodenal ulcer, rose sharply at the turn of the century and has shown a rapid decline in the past three decades. In the East, the rise was equally impressive, but the decline appears to have been delayed, only starting in the past decade. Asians present their ulcer symptoms a decade earlier than Caucasians, and it has been suggested that this early presentation may be attributable to Helicobacter pylori (H. pylori) infection at a younger age. Interestingly, the male-to-female ratio is much higher in the East than in the West, and the duodenal-to-gastric ulcer ratio manifests a much wider variation in Asians than in Caucasians. As in Western countries, peptic ulcer occurrence in the East shows a cyclical trend, with a peak frequency in the winter months. In the West, the placebo healing rate varies widely up to 78%, whereas in the East it is rather consistent at around one-third. These variations in geographical distribution, time trends, sex and ulcer ratios, seasonal rates and behavioral response to placebo treatment indicate that while H. pylori is a major cause of peptic ulceration, other environmental and genetic factors contribute to ulcer formation. The parietal cell mass and acid secretory capacity of Asian patients with duodenal ulcer are only slightly more than half of those of Caucasian patients, which may explain why Asian patients respond equally well to half the standard dose of anti-secretory agents used in Caucasians. H. pylori infection is generally more prevalent in the East than in the West and is more resistant to metronidazole. The response to standard triple therapies for eradication, however, appears to be as effective in the East as in the West.

Differences in peptic ulcer between East and West

There are suggestions that duodenal ulcer protects individuals from gastric cancer and that rice is ulcerogenic while wheat is gastro-protective. We aimed to examine the relationship of gastric cancer, duodenal and gastric ulcers in different geographical regions in China and identified dietary risk factors for duodenal ulcer and gastric cancer. The prevalence of peptic ulcer and gastric cancer among symptomatic patients in eight major cities, four each from the north and the south representing all the six defined regions of China were studied. Endoscopy and case records over a 10 year period were reviewed and cases of confirmed duodenal and gastric ulcer and gastric cancer, together with the total number of endoscopies performed per year, were recorded. Rates were expressed as cases/1000 endoscopies. Results were compared to another epidemiological study on diet and mortality in the same regions in China conducted at the same time. Duodenal ulcer rates were 2.4-fold higher in southern China than northern China, whereas gastric cancer rates were 1.6-fold higher in the north than in the south. Correlation studies showed for the first time an inverse linear relationship between the gastric cancer rates and the duodenal ulcer rates (r=-0.8076, P=0.015), as well as the duodenal ulcer: gastric ulcer ratios (r=-0.9133, P=0.002). Gastric ulcer rates were higher in southern China but did not correlate with the gastric cancer rates (r=0.1455, P=0.731). Duodenal ulcer rates were found to be related to daily rice intake (r=0.8554, P=0.029) and inversely related to daily wheat flour intake (r=-0.8472, P=0.033). Gastric cancer rates were not related to any dietary risk factors tested. We concluded there was an inverse relationship between gastric cancer rates and duodenal ulcer rates. Although duodenal ulceration and gastric cancer are both linked to Helicobacter pylori infection, the findings of this study indicate independent additional aetiological factors for the pathogenesis of these conditions. Dietary factors such as rice or wheat intake may play a role.

Differential north to south gastric cancer-duodenal ulcer gradient in China

The aetiology of duodenal ulceration is multifactorial. Various factors, such as genetic factors (including family history, sex, blood groups and secretor status), gastric secretions of acid and pepsin, drugs, stress and sometimes social class or occupation, may contribute towards a greater risk of developing a duodenal ulcer. Helicobacter pylori infection has been shown to be a factor in the occurrence of relapse after healing, although it is still uncertain as to whether it is a causal factor in the initial development of duodenal ulceration. In addition to the above factors, there is increasing evidence of a relationship to diet, and the possibility that, in people predisposed to developing a duodenal ulcer, one of the precipitating factors may be exposure to a certain pattern of staple foods in their diet.

Diet and duodenal ulcer.

There are five known environmental, causative factors for peptic ulcer, namely, non-steroidal anti-inflammatory drugs (NSAID), Helicobacter pylori infection, cigarette smoking, environmental stress and dietary habit. There have been six factual, epidemiological observations on peptic ulcer this century: the rise and fall of ulcer frequency in Western societies; geographical variations in ulcer rates; in sex ratios; in duodenal: gastric ulcer ratios; and in placebo healing rates; and seasonal variation in ulcer frequencies. This report examines each of these epidemiological observations to see if each of the environmental factors can explain the observations. The secular trends and the variation in ulcer rates can be related to all the environmental factors. The sex ratios can be explained on the basis of cigarette smoking and environmental stress, whereas the duodenal: gastric ulcer ratios may be ascribed to NSAID use. Placebo healing and seasonal occurrence of ulcer is probably more related to environmental stress. Helicobacter pylori infection alone cannot explain the sex ratios, the duodenal: gastric ulcer ratios, the placebo healing and the seasonal occurrence of ulcer. Cigarette smoking or NSAID use alone does not tally with the seasonal variation of ulcer frequencies. Environmental stress alone does not fit into the recent fall of ulcer rates in Western countries. This report supports the concept of heterogeneity in peptic ulceration.

Aetiological factors of peptic ulcer: perspectives of epidemiological observations this century.

The study consisted of 10 994 inpatients with peptic ulcer in Shan Dong province. The ratio of duodenal to gastric ulcer was 1.59 : 1. The ratio of males to females was 6.8 : 1 for duodenal ulcer and 4.6 : 1 for gastric ulcer. The highest incidence was in adolescence and young adults and the presentation occurred more commonly in winter. A study of blood groups revealed that there was no relationship between blood group and duodenal or gastric ulcer. The majority (71.9%) of patients with peptic ulcer had complications of upper gastrointestinal bleeding, perforation or gastric outlet obstruction. Bleeding and obstruction were equally common in gastric and duodenal ulcer, but perforation was more common in gastric ulcer.

Wan-Cheng Peng

Papers

Observations on peptic ulcer in Shan Dong, China