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dilatation and pelvic microcalculi, although found these observations to be lacking in temporal and dose-related qualities. The development of renal pelvic dilatation has been shown to be a polygenic heritable trait (3) and so the investigators concluded this to be a factor. Additionally, dietary protein is also implicated as a causative factor in the development of pelvic dilatation (4), so this observation was not considered persuasive.
Cocoa and chocolate contain intrinsic methylxanthines, predominantly theobromine with small amounts of caffeine. Methylxanthines as a group are well-known diuretics and reportedly contribute to urinary mineral excretion when consumed at high levels (see Chapter 10 (5)). However, no other impact upon the kidney has been reported from the consumption of cocoa or chocolate.
The subject of microcalculi formation and urinary excretion of minerals is covered in more detail in Chapter 9. Gastrointestinal Effects
Some patients have tended to report heartburn symptoms following chocolate consumption and reportedly with some frequency. This led Babka and Castell (6) to further investigate this claim. They demonstrated that immediate and sustained lowering of the pressure of the lower sphincter of the esophagus could be induced experimentally with ingestion of chocolate as well as some other foods.
The esophagus is a tube-like structure connecting the mouth to the stomach (Fig. 19.1). Since the stomach usually has a higher pressure than that of the esophagus, a specialized muscle closes off the esophagus from the stomach at the point of joining. This is called the lower esophageal sphincter (LES). During normal eating, the LES relaxes after swallowing to allow food to pass into the stomach, and then quickly closes again. In most people, this system functions adequately, but in approximately 10% of the US population who suffer daily and 33% who suffer occasionally, this system is inadequate. In these individuals, the LES is either weak, or more commonly, relaxes inappropriately, allowing a backwash of acidic stomach contents into the esophagus, thereby irritating the esophageal lining (7).
The original studies by Babka and Castell (6) measured pressure of the LES in normal subjects following administration of either water (control), whole milk, non-fat milk, orange juice, water/tomato paste mixture and dilutions of chocolate syrup. Whole milk was found to lower LES pressure, to a significant (P <0.05) but lesser extent than the chocolate syrup (P <0.005). Orange juice and the tomato preparation both showed transient decreases in pressure followed by a gradual return to baseline and 'considerable pressure variation and secondary contractions'. It was first thought that the high fat content alone was responsible for this effect; however, a further study (8) was conducted using chocolate syrup
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