The Health Library's explanation of why the blood level of
bicarbonate is important:
Bicarbonate is a major element in our body. Secreted by the stomach, it is necessary for digestion. When ingested, for example, with mineral water, it helps buffer lactic acid generated during exercise and also reduces the acidity of dietary components. Finally, it has a prevention effect on dental cavities.
Bicarbonate is present in all body fluids (see table) and organs and plays a major role in the acid-base balances in the human body. The first organ where food, beverages and water stay in our body is the stomach. The mucus membrane of the human stomach has 30 million glands which produce gastric juice containing not only acids, but also bicarbonate. The flow of bicarbonate in the stomach amounts from 400 µmol per hour (24.4 mg/h) for a basal output to 1,200 µmol per hour (73.2 mg/h) for a maximal output. Thus at least half a gram of bicarbonate is secreted daily in our stomach. This rate of gastric bicarbonate secretion is 2-10% of the maximum rate of acid secretion. In the stomach, bicarbonate participates in a mucus-bicarbonate barrier regarded as the first line of the protective and repair mechanisms. On neutralization by acid, carbon dioxide is produced from bicarbonate. A study has underlined that a dose of 6.17 g of sodium bicarbonate rapidly leaves the stomach with the liquid phase of the meal.
For digestion, bicarbonate is naturally produced by the gastric membrane in the stomach. This production will be low in alkaline conditions and will rise in response to acidity. In healthy individuals this adaptive mechanism will control the pH perfectly. To modify this pH with exogenous doses of bicarbonate, some clinical experiments have been conducted with sodium bicarbonate loads as high as 6 g. Only a transient effect on pH has been obtained. It is quite possible that bicarbonate in water may play a buffering role in the case of people sensitive to gastric acidity. Thus bicarbonate may be helpful for digestion.
The most important effect of bicarbonate ingestion is the change in acid-base balance as well as blood pH and bicarbonate concentration in biological fluids. It has been studied particularly in physically active people. Among the types of acid produced, lactic acid generated during exercise is buffered by bicarbonate. In a study on sports, a dose of 0.3 g per kg of body weight of sodium bicarbonate was given (15.25 g bicarbonate for a man of 70 kg) to subjects before performing 30 minutes cycling. While blood pH was increased and then maintained constant with this bicarbonate load due to the changes in blood bicarbonate concentrations, increased acidity and decreased bicarbonate blood concentration were observed in controlled subjects. Mineral water which contains bicarbonate (>600 mg/l) may have an effect on acid-base balance. It is the case of Qu zac. The daily consumption of 1.5 liter of Qu zac in healthy subjects has produced a significant increase in the urinary pH due to the ingested bicarbonate (1685 mg/l).
Bicarbonate also reduces the acidity of dietary components such as proteins. As an example, adding sodium or even more potassium bicarbonate to subjects on a high protein diet known to acidify urine and leading to hypercalciuria (high level of calcium in urine) has been shown to greatly reduce calcium urinary excretion. The effect has been observed with 5.5 g of bicarbonate supplement received daily for two weeks. A recent study presented in the review of literature highlights that a bicarbonate-rich mineral water could be useful in the prevention of the recurrence of calcium oxalate and uric acid renal stones.
Many oral hydration solutions contain bicarbonate showing the usefulness of bicarbonate to control water absorption in patients at risk of dehydration.
Sodium intake is restricted in patients with hypertension, but it is demonstrated that the accompanying anion, such as bicarbonate or chloride, plays an important role. It is now well established that sodium bicarbonate as well as citrate and phosphate salts do not raise blood pressure to the same extent as do the corresponding amounts of sodium chloride. A study on mineral water containing sodium bicarbonate has confirmed the absence of effect on blood pressure in elderly individuals.
Bicarbonate has been shown to decrease dental plaque acidity induced by sucrose and its buffering capacity is important to prevent dental cavities. Other studies have shown that bicarbonate inhibits plaque formation on teeth and, in addition, increases calcium uptake by dental enamel. This effect of bicarbonate on teeth is so well recognized that sodium bicarbonate-containing tooth powder was patented in the USA in October 1985. Sodium bicarbonate has been suggested to increase the pH in the oral cavity, potentially neutralizing the harmful effects of bacterial metabolic acids. Sodium bicarbonate is increasingly used in dentifrice and its presence appears to be less abrasive to enamel and dentine than other commercial toothpaste.
An ingestion of 300 mg/kg of body weight of bicarbonate before exercising will help you reduce muscular fatigue and so increase the performance of short- term physical exercise. Thus drinking mineral water containing bicarbonate may contribute to this beneficial intake.
Sportsmen continuously have two problems to solve : the other athletes to overtake and fatigue to overcome. The causes of fatigue are multifactorial, either they have physiological or psychological origins. From the physiological point of view, fatigue can have a central or peripheral origin. Among the peripheral causes, fatigue could be due to the accumulation of metabolites in muscle, such as lactates, hydrogen ions and ammonia. During prolonged submaximal effort, the major cause of fatigue is the energy substrate depletion (namely carbohydrates), but it has been shown that hyperthermia (over 40.1 C) or dehydration (over 1 or 2 % of body weight loss) could also contribute to the occurrence of fatigue.
In fact, to optimise performance, it is important to minimise fatigue and to delay its appearance. Athletes are aware of substances which could offset fatigue and since the 90s the use of sodium bicarbonate has become usual among sportsmen to buffer the acids produced during exercise.
The pH is a parameter expressing the acidity of a solution. Neutral pH is 7. For example, the pH of blood is normally 7.4 and that of muscle is 7.0. pH under 7 is acid, that is the case of vinegar (pH =3), orange juice (pH =3.7 ) or cola-drinks (pH =2.4). pH over 7 is basic or alkaline. Some mineral waters are alkaline, such as Abatilles (pH = 8.2).
Physical exercise can imply the production of lactic acid, leading to the acidification of pH in blood and muscle. In order to buffer this accumulation of lactic acid and to regulate the acid-base balance, the body uses biological buffers, especially the bicarbonate buffer system. But under conditions of intense physical activity (short or long-term), this natural buffer is limited and accumulation occurs with the risk of fatigue.
The ingestion of sodium carbonate as a buffering agent has been studied in various experimental designs (repeated short bout exercises or long lasting efforts) and with large dose ranges (100 to 500 mg per kg body weight, ingested or injected). Plasma bicarbonate concentrations were shown to increase after oral ingestion but intracellular concentrations of bicarbonate in muscle were unchanged. However, recent studies underline that bicarbonate increases the transport of lactate from muscle. General considerations can be drawn from the 46 studies showing enhancements of exercise performance and 37 studies showing no enhancement : below 200 mg per kg body weight of sodium carbonate ingested, no effect on performance occurs. The optimum range to observe an effect seems to be around 300 mg per kg of body weight. Sodium bicarbonate ingestion is efficient for long lasting efforts, between 1 to 7 minutes (sprint, 200 m, 400m, 800m and 1500m). When cycling, running, swimming, rowing and weightlifting exercise performance is increased by sodium bicarbonate ingestion. Recently, a few studies have shown that sodium bicarbonate and sodium chloride have the same ergogenic effect leading to the conclusion that the effect attributed to bicarbonate buffering may be due to sodium.
Even if the mechanism of the effect of bicarbonate is a matter of discussion, it is clear that at a dose close to 300 mg per kg of body weight of ingested bicarbonate increases the buffering capacity of blood and may decrease the acidity of the muscle pH. As a consequence, acid accumulation will be attenuated and energy production or force maintained. The improved acid balance obtained by this administration produces a reduction of fatigue and an enhancement of strength recovery.
Natural mineral or spring waters have various contents of bicarbonates, from some tens to hundreds of mg/litre for still waters and from several hundreds to thousands of mg/litre for sparkling waters (see table). Although studies have shown an effect on acid-base balance of some mineral waters containing more than 600 mg of bicarbonate per litre, physically active people need to drink large amounts of water to observe an effect on fatigue when exercising. In athletes, several authors have shown a significant increase in blood pH and blood bicarbonate without improvement of performance.
Moreover, if the optimum content of bicarbonate ingestion is close to 300 mg per kg of body, this means for a 70 kg sportsman a dose of about 15 g of bicarbonate. Accordingly, the ingestion of water alone will help reach an efficient dose of bicarbonate, if a large volume of water is taken several hours before exercising. It could contribute to lowering the bicarbonate load to be ingested and avoiding the possible gastrointestinal side-effects.
San Pellegrino: 219.6 mg per litre
Perrier: 390 mg per litre
Vittel: 402 mg per litre
Campilho: 1479 mg per litre
Qu zac: 1685.4 mg per litre
San Narciso: 2165.5 mg per litre
-- "Normal adult humans eating Western diets have chronic,
low-grade metabolic acidosis ...." Frassetto LA, Todd KM, Morris
RC Jr, Sebastian A(1998) Am J Clin Nutr, 68 (3): 576-83
Estimation of net endogenous noncarbonic acid production in humans from diet potassium and protein contents
-- "Previously we demonstrated that low grade chronic
metabolic acidosis exists normally in humans eating ordinary
diets ... and that the degree of acidosis increases with age."
Frassetto L, Morris RC Jr, Sebastian A. (1997) J Clin Endocrinol
Potassium Bicarbonate Reduces Urinary Nitrogen Excretion in Postmenopausal Women
-- "In normal subjects, a low level of metabolic acidosis and
positive acid balance (the production of more acid than is
excreted) are typically present ..." Sebastian A, Harris ST,
Ottaway JH, Todd KM, Morris RC Jr(1994) N Engl J Med, 330 (25):
Improved Mineral Balance and Skeletal Metabolism in Postmenopausal Women Treated with Potassium Bicarbonate
-- "The lysosome system [acidic denaturing interior] provides
the only intracellular environment capable of performing this
pathological processing, and the recent observations reviewed
here suggest that it lies at the heart of the pathogenesis of
these diseases [Creutzfeldt-Jakob disease, Alzheimer's disease,
neuronal ageing and neuronal cell injury]." Mayer R J, Landon M,
Laszlo L, Lennox G, Lowe J. (1992) The Lancet, Jul
Protein processing in lysosomes: the new therapeutic target in neurodegenerative disease
-- "Human metastatic breast cancer cells in culture contain
large acidic vesicles ..... large acidic vesicles were associated
with both phagocytosis and invasion ....." Montcourrier P,
Mangeat PH, Valembois C, Salazar G, Sahuquet A, Duperray C,
Rochefort H. (1994) J Cell Sci 1994 Sep;107 ( Pt
- "Only a narrow pH range is compatible with life because even
a small increase in [H+] [that is, cell acidity] has dramatic
effects on normal cell function." "The major source of H+ [acid]
is ... metabolically produced CO2 [carbon dioxide]." Sherwood, L.
(Third Edition). 1994. Human Physiology. From Cells to Systems.
-- "The crux of H+ [acid] balance [in the body] is maintaining
the normal alkalinity of the extracellular fluid (pH 7.4) despite
the constant onslaught of acid." Sherwood, L. (Third Edition).
1994. Human Physiology. From Cells to Systems. p. 531
Fluid and Acid-Base Balance
Researchers found a link between the severity of some forms of cystic fibrosis and the ability of a key protein to move particular molecules -- bicarbonate ions -- across cell membranes.
Kessler T, Hesse A
British Journal of Nutrition, 84, 6, 865-87, (2000)
High fluid intake is the first general recommendation made to lithiasis patients for the prevention of renal stone recurrence. The aim of the present study on healthy male subjects aged 23-38 years was to evaluate the influence of bicarbonate-rich mineral water (1715 mg bicarbonate/l) on urinary-stone risk factors in comparison with sodium potassium citrate, a well-established treatment in that case. The results showed that the effect of the bicarbonate-rich mineral water was similar to that of the sodium potassium citrate, which suggests that it could be useful in the prevention of the recurrence of calcium oxalate and uric acid stones.
For people with the rare illnesses of Bartter syndrome or Gitelman syndrome, bicarbonate may be contraindicated. These rare sufferers may add a few drops of Real-Lemon juice concentrate to any bicarbonate-containing beverage to neutralize it. [Bartter's is listed as an orphan (rare) diseases with the National Organization of Rare Diseases (NORD); they don't even list Gitelman's, but include it under Bartter's.]
Updated on January 15, 2004
This page was first uploaded to The Magnesium Web Site on November 14, 2002