Although, no difference was observed between the two waters in this pilot study, we showed that the consumption of high mineral water (SY) during eight weeks in moderated hypercholesterolemic subject induced a decrease in plasma and VLDL TG and tended to decrease VLDL cholesterol. This high mineral water did not affect lipids parameters at postprandial state.
In our study, no change in blood pressure was observed. Hypertensive effect of sodium has been noted when accompanied by chloride but not by bicarbonate [23
]. This explains that, although mineralized water of our study provided 2 grams per day of sodium, no change in blood pressure was noted as this water provided 5 g of bicarbonate but only 0.4 g of chloride.
At the postprandial state, plasma TG, VLDL TG and chylomicron TG concentrations were not affected by water consumption (referent or SY). In contrast to our study, previous data, from the same team, reported an improvement of lipidic charge in postprandial state by water rich in bicarbonate [15
]. The absence of effect of bicarnonated water on postprandial lipemia in our study was unexpected and could be explained by the lower energetic meal provided in our study (1089 Kcal in the two studies vs 799 Kcal in ours). Although we have used a meal rich in fat (42% VS 36%) to stimulate postprandial lipemia, this lipidic charge was not sufficient to induce a higher postprandial triglyceridemia. In fact, the elevated TG that we measured during postprandial test, whatever the water consumed, is lower than what is classically reported [15
]. Studies investigating postprandial lipemia provided more than 1000 Kcal and at least 60% of calories from fat [16
]. Thus we suppose that the increase of lipidic charge in postprandial test could induce a significant hypertriglyceridemia during meal absorption and higher probability to measure a bicarbinated water effect. Moreover a strong association has been reported between postprandial triglyceridemia and early atherosclerosis markers [6
] which suppose that fasting triglyceridemia is tightly dependent on the postprandial lipemia. Indeed, as soon as 1979, Zilversmit proposed that atherosclerosis was a postprandial phenomenon [29
In the present study SY chronic ingestion induced a decrease in plasma TG related to a diminution of VLDL TG. We also reported a tendency to decrease VLDL cholesterol. The improvement of plasma lipid and cardiovascular risk by chronic ingestion of a high bicarbonate water was also reported by other studies [13
] with differential effect on lipoproteins. Some studies reported a decrease in LDL cholesterol [13
] and others showed a decrease in LDL cholesterol associated with an increase in HDL cholesterol [15
] were reported. In this series of experiments, effect on TG was observed only in postprandial state while no change was observed in fasting state. One probable mechanism that could explain the decrease of VLDL TG in our work is a postprandial lipemia effect, although not observed in our study. As discussed higher a strong association has been reported between postprandial triglyceridemia and fasting lipid levels [30
]. In fact, intestine derived lipids during absorption modulates liver VLDL synthesis and secretion which could affect triglyceridemia measured in fasting state [31
These different results showing effect on cholesterol in almost studies [13
] and on triglycerides in our case, could be related to the mineral composition of used waters. SY water is characterized by, a higher mineralization compared to the others studies and among anions a higher concentration in bicarbonate and almost a lower one in chloride. SY is water richer in bicarbonated (4167 mg/L) and less rich in chloride (329 mg/L) and contains a very high molar ratio HCO3/Cl (7.3). We did not observe any effect on LDL cholesterol, potentially described as bile acid dependent [13
] but we observed an effect on plasma and VLDL TG. Effect on plasma cholesterol and bile acid excretion has been initially observed in the pioneer study of Capurso et al
]. In this later study, authors have used Montecatini water witch correspond to a low bicarbonate (677 mg/L) and low chloride content (922 mg/L) and then a very low molar ratio HCO3
/Cl (0.43). The same effect was recovered in the studies of Vaquero’s laboratory [14
] using a water (Vichy-Catalan) more bicarbonated (2094 mg/L) but even rich in chloride (583 mg/L) and then an intermediate molar ratio HCO3
/Cl (2.1). It is well known that chloride and bicarbonate have differential effects on vascular parameters [24
]. It has been also shown that a high concentration of NaCl increased gallbladder motility [35
] that could be related to bile acid excretion. Thus it could be credible to hypothesize that bicarbonated waters with a high Cl/HCO3
ratio could affect plasma cholesterol by the stimulation of bile acid excretion, while water with low Cl/HCO3
ratio affect mainly TG concentration by affecting intestinal absorption.