Osteoporosis is a skeletal disorder characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequence increase in the fragility of bone and hence susceptibility to fracture (1). Although it's often thought of as a women's disease, osteoporosis affects men too. It is estimated that more than 200 million people worldwide have osteoporosis (2). Moreover, the annual cost of all osteoporosis-related fractures combined is estimated at 20 billion dollars in the USA and 30 billion dollars in the European Union (1).

The risk factors of the bone’s fragility

A number of factors can increase the likelihood that you'll develop osteoporosis: some you can change (imbalanced diet, low calcium intake, tobacco use, sedentary lifestyle, excessive alcohol consumption…), and others you cannot (being a woman, getting older, race, family history...). However, it's never too late — or too early — to do something about osteoporosis. You can take some steps to keep your bones strong and healthy throughout life. Amongst those steps, it’s essential to provide your body with adequate amounts of calcium.  In fact, a lifelong lack of calcium plays a major role in contributing to diminish bone density, early bone loss and an increase risk of fractures (3). Therefore, optimization of calcium status must be ensured by covering the calcium needs as defined by the Dietary Reference Intakes.

Calcium and the evolution of bone mass

Calcium is one of the main bone-forming minerals and an appropriate supply to bone is essential at all stages of life.

Throughout growth, ensuring sufficient calcium and vitamin D intake can be considered as a precocious preventive measure against adult osteoporosis (4). In fact, your bone is continuously changing — new bone is made and old bone is broken down (resorption) — a process called remodeling or bone turnover. When you're young, your body makes new bone faster than it breaks down old bone and your bone mass increases. You reach your peak bone mass around age 30. After that, bone remodeling continues, but you lose slightly more than you gain. How likely you are to develop osteoporosis depends on how much bone mass you attained in your 20s and early 30s (peak bone mass) and how rapidly you lose it later. The higher your peak bone mass and the less likely you are to develop osteoporosis as you age. (3)

After menopause, we experience significant bone loss particularly throughout the first 5 years because of decreased estrogen production (5-6). The bone loss is less thereafter throughout the late postmenopausal period, and becomes increasingly influenced by nutritional factors (calcium, protein, vitamin D) and/or environmental factors (physical activity, exposure to sunshine).

In all cases, the prevention of osteoporosis entails, among other things, sufficient calcium intake at every age in life.

Well-defined but often insufficiently met calcium needs

The calcium Dietary Reference Intakes differs from country to country. For example, in France, the calcium Dietary Reference Intakes are 1200 mg/day for an adolescent, 900 mg/day for an adult, and for women older than 55 and men older than 65, 1200 mg/day (7). In Europe and in the United States, these values are different: for example, 800 mg/day for an adult in Europe (8) and 1000 mg/day in the USA (6).

These needs are not always met.

Dairy products are one, but by no means the only, source of calcium. Calcium-rich mineral waters are very interesting potential source of calcium when dairy consumption is insufficient to meet the calcium Dietary Reference Intakes.

Calcium-rich mineral waters, an interesting source of calcium

A mineral water is considered rich in calcium when it contains more than 150 mg/l of calcium. Certain natural mineral waters contain more than 500 mg/l of calcium. Many studies have shown that the calcium provided by calcium-rich natural mineral waters has an intestinal absorption similar to that of the calcium present in dairy products. Therefore, according to the quantity of calcium ingested, the absorption rate will be between 23 and 47.5% (9).

Thus, drinking 1 liter of calcium-rich mineral water (for example ≥ 400 mg/l) goes back to meeting at least 44 % of the Dietary Reference Intakes of calcium for an adult and 33% of the Dietary Reference Intakes of calcium for an adolescent or an older person (according to the Dietary Reference Intakes in France). (9)

The consumption of a natural mineral water rich in calcium can therefore constitute as a suitable recommendation for the global nutrition support aimed at ensuring sufficient calcium intake, in the prevention of osteoporosis.

References

• 1. Holroyd C et al. Epidemiology of osteoporosis. Best Pract & Res.Clin.Endocrinol & Metab 2008, 22 (5): 671-85
• 2. Cotté et al. Relationship Between Compliance and Persistence with Osteoporosis Medications and Fracture Risk in Primary Health Care in France: A Retrospective Case-Control Analysis. Clin Ther. 2008, 30 (12) :2410-22
• 3. Mayo Clinic staff. Osteoporosis. http://www.mayoclinic.com/health/osteoporosis/DS00128 Accessed 9 May 2011
• 4. JP Bonjour et al. Lait en santé osseuse : rôle essentiel du calcium et des protéines. Cah Nutr Diet, 40, Hors série 1, 2005
• 5. GRIO. Ostéoporose, prévenir et agir à tout âge. http://www.grio.org/documents/prevenir_agir.pdf 2005, p.1-26.
• 6. IOM: Dietary Reference Intake: the essential guide to nutrient requirements 2010, p.1-543.
• 7. Martin A. Apports nutritionnels conseillés pour la population française. Editions TEC & DOC, 3ème édition ; 2001, p.1-605.
• 8. Official Journal of the European Union. Commission Directive 2008/100/EC of 28 October 2008 amending Council Directive 90/496/EEC on nutrition labelling for foodstuffs as regards recommended daily allowances, energy conversion factors and definitions.
• 9. Constant F, Hawili N. Les eaux embouteillées. Cah Nutr Diet 2011, 46: 40-50

Sweating is useful, inevitable, and varies from one runner to another

The adult human body contains about 60% of water and every day a healthy sedentary adult living in temperate climate loses on average 2.5 litres of water (1). One part of these losses has to do with sweating. In these climate and physiological conditions sweating is minimal (0.45 liter per day) but can reach high levels for a sportsman during long periods of exercise (a marathon runner, for example) in strong heat.

Of course, the degree of sweating depends on the power and speed of the course, its length, the state of the runner’s physical condition and acclimation to the heat, as well as climate factors (temperature and humidity in the air, windshield factor) and the clothes that the runner wears.(1-2)

Certain scientists (2-3) have predicted the sweat losses of marathon runners as a function of their weight, their speed on the course, and the temperature outside. The sweat loss goes from 0.43 liter/hour (50 Kg weight, slow course, 18°C) to 1.76 liters/hour (90 kg weight, very fast course, 28°C).

Sweating is necessary because it helps both the thermoregulation of the runner and limits the risks of hyperthermia (1). It therefore does not have to be hindered, but on the contrary, supported, by wearing loose-fitting clothes which help the circulation of air.

However, it is not without consequences because it increases the risk of dehydration if it is not compensated during the course.

Dehydration: synonymous with  decrease in performance for the marathon runner

Dehydration leads to a decrease in blood volume, an increase in heart beat and an increase in internal temperature. This can lead to:

• -   thirst
• -   fatigue
• -   headaches
• -   muscle weakness
• -   impairment in mental performance (concentration, alertness)
• -   impairment in physical performance (endurance, sports skills)
• -   underachievement, or even heat stroke.(1-2)

Overall, the drop in performance is proportional to the level of dehydration expressed as a percentage of body weight.

The regular consumption of drinks during the course considerably decreases the risk of dehydration.

The main recommendation: drink before being thirsty

Before the marathon:

- In the days prior: in the week preceding the start, be sure to get more of your calories from carbohydrate (bread, starches at every meal, fruits and sweet products)and fewer from fat, the balance coming from protein. It is also important to start the course in a normal state of hydration (2). Therefore, drink at least 1.5 liters of water regularly throughout the day(1).     

- Before the start: don’t eat in the 3 hours prior. For example, if you have a 9 am start, plan breakfast at 6 am.

Drink before you race. Drink water slowly at least 4h before the race to enable fluid absorption and allow urine output to return to normal levels. If your urine is dark, you should slowly increase your water intake about 2h before the event.(2)

During the marathon:

- When to start drinking ?

It is necessary to drink early and repeatedly small amount throughout the course of exercise before you start to feel thirsty because when thirst occurs it means that you are already dehydrated. Therefore, the goal of drinking during the race is to prevent dehydration.(2)

The International Marathon Medical Directors Association recommends to marathon runners to drink ad libitum from 0.4 to 0.8L/h, with the higher rates for the faster, heavier runners competing in warm environments, and the lower rates for the slower, lighter runners competing in cooler environments.(2-3)

- What to drink ?

For all sports that last for more than one hour, it’s recommended to consume carbohydrate and sodium via food or fluid. However, it is important to know to adapt oneself to the context. In fact, the need for these different components will depend on the specific exercise task (e.g., intensity and duration) and weather conditions.(2)

- How to drink ?

Slow down through the fluid stations and grab a drink. Don’t be tempted to miss out the early fluid stations to gain valuable time – dehydration later on will slow you down even more.

After the marathon, it is important to compensate any fluid and electrolytes deficit. If time permits, consumption of normal meals and snacks with a sufficient volume of water will restore normal hydration status.(2) Moreover, because the muscles have produced a lot of lactic acid, we can recommend a water rich in bicarbonates such as some carbonated mineral water.

After the marathon

Individual needing rapid and complete recovery from excessive dehydration can drink ~1.5L of fluid for each kilogram of body weight lost.(2)

Watch your weight and concentration of urine: in fact, a marathon runner who has not recovered his or her initial weight and does not have clear urine the next day, has to increase his or her water intake to compensate for this dehydration.

In conclusion, for the marathon runner, it is essential to start the course well hydrated and without deficiencies (balanced and varied diet in the days prior to the start). During the course, the runner should start drinking very early and regularly between 0.4 to 0.8L/h, with the higher rates for the faster, heavier runners competing in warm environments, and the lower rates for the slower, lighter runners competing in cooler environments. Thus, we can prevent dehydration which will be compensated for in the hours following the end of the marathon.

Click here to learn more about hydration.

References:

1- Jequier et al. Eur J Clin Nutr. 2010; 64(2):115-23.

2- Sawka et al. Medicine & Science in Sports & Exercise. 2007 : 377-390

3- Montain SJ et al. Br J Sports Med. 2006; 40: 98-106,

Photo credit by ASO

The notion of dehydration is often attached to the notion of heat and exercise. Many also underestimate the risk of dehydration during climbs up high mountains in the winter. Yet the risk of dehydration is particularly elevated for several reasons.

In high altitudes, the mountain dweller has several reasons to quickly dehydrate: he breathes dry and hydrophilic air, he hyperventilates, and he is put under low atmospheric pressure. To all of this, he adds an intense physical activity, the source of considerable sweating.

1 – With the altitude and the cold, hygrometry quickly diminishes: at 4000 meters, it already represents less than a quarter of what exists at sea level, and at the summit of Everest, it is close to zero (1) . In high mountains, the air is therefore very dry. It is hydrophilic, meaning that it attracts the water vapor contained in the air that the sportsman exhales.

2 – Due to a lack of oxygen, the exertion in altitude increases ventilation: the ventilated air volume can thus be ten times larger than at rest at sea level (10 liters per minute to 100 liters per minute (1). That’s how respiratory losses of water can reach the equivalent of a full glass of water (200 ml) per hour, very well close to one liter after 5 hours of progression in altitude! (2)

3 – Sweating is real but often passes unnoticed; in fact, due to the weak hygrometry environment, the process of the evaporation of sweat is extended, which diminishes the sensation of perspiring because the sweat evaporates very fast. A mountaineer in full exertion can lose 1 liter of sweat per hour.(2)

In sum, sweat and respiratory losses add together to reach record values of 4 to 5 liters per day.(2) In these conditions, all insufficient water intake leads to dehydration, which runs the risk of severe complications: exhaustion, frostbite, and impairments to lucidity.

Therefore, it is very important that the high mountain sportsman drinks at least ½ liter of water per hour of exertion: dietary drinks already supplemented with glucose, salt, potassium, and vitamins, or traditional drinks (water added with a little sugar, salt, and vitamins). He knows that he must drink before being thirsty.

Many experienced mountaineers testify to the difficulty of drinking sufficiently because water is heavy! They often bring 1 to 2 liters of water for the day and choose to make up for the shortage at camp at night, most often with melted snow! It’s there that the areas of theory and practical possibilities struggle to meet, to the detriment of the physical capabilities of the mountain dweller.

References

(1) Dr Emmanuel Cauchy, Founder of the IFREMMONT - Institut de Formation et de Recherche en Haute Montagne.(French High Mountains Institut for Research and Training)

(2) Interviews and recommandations of Dr Jean-Louis Etienne (Médecine des randonnées extrêmes: des Pôles aux plus hauts sommets Editions du Seuil / 7ème Continent 2004)

Gastroenteritis is an infection of the digestive system caused by viruses, bacteria, or parasites, and which causes nausea, vomiting, abdominal cramps, and diarrhoea. The symptoms occur violently and generally disappear after 1 to 3 days, subject to adopting good habits and not suffering from dehydration, much dreaded for infants, young kids, elderly people, and people who are already sick.

We will only talk about viral gastroenteritis here, particularly frequent in the winter. A number of viruses can be the cause, but the most common is the rotavirus, especially in kids.

It is easily passed on, through saliva and hands

It is the route called « fecal-oral ». We can contract the illness if, after having touched a contagious person or some contaminated objects or surfaces, we touch our face with our hands or we prepare a meal without having properly washed our hands. An affected person is contagious from the moment that symptoms begin until around 48 hours after they disappear.

Warning: Healthy adults can contract gastroenteritis without necessarily having symptoms (or in having very mild symptoms). Even if they are themselves « immune », they are contagious and can contribute to the spreading of epidemics.

Let’s remember therefore the necessity of washing our hands with soap (and/or hydro-alcoholic gel) several times per day and always before eating.

The people the most exposed are those who work in groups (employees of schools, hospitals, transportation services…) and those who live in groups (kids, teenagers, the ill, hospitalized elderly people, employees of companies)…in other words, almost everyone!

What are the symptoms of gastroenteritis?

In the case of viral gastroenteritis, the symptoms occur 24 to 48 hours after contamination. They generally last for 1 to 3 days and can unusually persist for up to 7 days: violent appearance of nausea, vomiting, abdominal cramps, severe fatigue, and possibly a light fever (38°C).

If we don’t properly hydrate ourselves, then signs of dehydration appear: dryness of the mouth, dark and infrequent urine, muscle cramps, weight loss, drop in blood pressure, and dizziness, or even fainting. To avoid all of this, all you have to do is drink sufficiently!

The people at risk…

Of course the people the most at risk for severe dehydration are infants, young kids, elderly people, and people with an immune system weakened by an illness or by immunosuppressant medication, such as anti-rejection medication for transplant patients, chemotherapy, and long-term, high-dosage corticoids.

It is urgent to consult your doctor when signs of complications (intense dehydration) appear, such as extreme fatigue, dry mouth, the start of mental confusion or extreme exhaustion in infants, or a concerning drop in blood pressure.

In this case, hospitalization might be necessary. Doctors then put in an intravenous drip to quickly rehydrate the body.

To avoid coming to this, you must sufficiently hydrate yourself as soon as diarrhoea first appears.

How to treat gastroenteritis

Most affected people recover in the space of 1 to 3 days. The goal of treatment is to rehydrate oneself and to prevent dehydration.

1 – Isolate and rest yourself

It is better to stay at the house and rest. This prevents contaminating others and increases the chances of a fast recovery.

2 – Then, drink, drink, drink…

To avoid dehydration, it is important to regularly and sufficiently drink at least 2 liters of water throughout the day. Of course, this water must be drinkable. In sum, drink every hour, or even every 30 minutes in the case of serious diarrhea.

The World Health Organization has developed an Oral Rehydration Solution (ORS) formula recommended in the case of acute diarrhoea, and particularly useful in developing countries (cholera epidemics…), as good for kids as for adults. This formula contains a suitable proportion of glucose, sodium, and potassium to effectively fight against dehydration and increase the ability to recover.

3 – Don’t eat fiber as long as diarrhoea persists

Through good food choices, keep a low-fiber diet as to not irritate the intestinal wall. That is why, during periods of diarrhoea, avoid vegetables, fruits, whole grain cereals, pulses, and spices.

Here are foods that you can count on: yogurts (but not milk nor white and Swiss cheeses), cheese, meat, fish or eggs, starches such as rice, pasta, potatoes, semolina, tapioca, bread, biscuits (avoid Viennese pastries), crackers, bananas, carrot purée, quince jelly.

For example:

- Breakfast: a yogurt, half a banana, a light tea, one or two lightly buttered biscuits or bread

- Mid-morning: drink water or ORS

- Lunch: fish and rice, yogurt and banana. Drink water and salt the dishes

- Afternoon: drink water, broth, ORS…

- Dinner: ham, pasta with Gruyere, yogurt, banana.

After 3 to 4 days, the transit is easily better. You can start to bring in compotes and cooked tender vegetables. At the end of the week, your diet is normal.

DR Laurence PLUMEY

Reference:

- OMS : printable document available on www.who.int 

Urinary lithiasis (pathological formation of mineral concretions) is a common pathology that has increased considerably over the past half-century in all of the industrialized countries (1), consistently with the increase in food consumption (2). Today, in  most cases, calcium oxalate is the main component of kidney stones, at the expense of phosphate, uric acid, and urate (1, 3).

Among the factors that increase the risk of urinary lithiasis, abnormally elevated urinary calcium excretion is the most frequently observed anomaly (3). As such, for many years, hypercalciuria being known as a predictive factor of  stone recurrence, it was customary to recommend a limited calcium intake through food and drink,  about 400 mg per day, to prevent recurrences (3-4).

This  advice not only proved to be ineffective, but currently in light of numerous scientific data, it is even recommended to maintain a calcium intake close to 1g of calcium per day, associated with a daily water consumption of at least 2 liters. Let’s look at the scientific data that led to these recommendations.

The Risks Related to a Decrease in Calcium Intake

Some American epidemiological studies showed that the risk of stone recurrence is strongly increased in consumers with low calcium intake

This is explained by the fact that calcium restriction increases oxaliuria. Indeed, in decreasing dietary calcium, the complexion of free oxalates by the calcium is reduced in the small intestine, and thus  their absorption is promoted at a colic level. In other words, oxalic acid excretion will be diminished in stools and increased in urine.

This results in an increased risk of calcium oxalate stone formation because the supersaturation of urine in calcium oxalate depends more on oxaliuria variations than on calcium variations on the physical and chemical level (3).

Furthermore, not only could calcium intake restriction lead to stone recurrence, but also, it is potentially harmful for the bone mineral density of patients. In fact, calcium intake reduction worsens bone demineralization and may predispose people to a negative calcium balance, thereby raising the risk of osteoporosis (3-6).

It is therefore not wise, but on the contrary, to prescribe calcium intake restriction to people at risk for kidney stones.

The Most Appropriate Calcium Intake seems to be Close to 1g per day

The conclusions of several studies seem to opt for the recommendation of about 1g of calcium per day, which is close to the Recommended Dietary Allowances in France (7). 

In fact, long-term epidemiological studies conducted by Curhan GC et al., have found an inverse relationship between daily calcium intake and the risk kidney stone formation (8-9). One study was carried for 14 years on 45,619 men (8) and the other for 12 years on 91,731 women (9) not suffering from urinary lithiasis. As daily calcium intake was closer to 1g/day, the risk of lithiasis lessened. In addition, further analysis of the first cohort confirmed that a daily calcium intake close to 1g reduces the risk of lithiasis for subjects younger than 60 (10).

Moreover, a prospective study, conducted on 96,000 young women without a prior history of lithiasis (11), confirmed the protective effect of calcium and showed that it is not limited to recurring cases.

On the contrary, beyond 1.2g of calcium intake, the decrease of intestinal oxalate absorption becomes negligible (3). As for the moment of consumption of this calcium intake and its impact on oxaliuria, it seems that the reduction of oxaliuria would be greater when calcium intake happens during meals (12).

Water and Dairy: a Subtle Dosage for Lithiasic People

In practice, a patient suffering from calcium oxalate lithiasis should follow the recommendations hereafter:

- Drink at least 2 liters of water per day to ensure diuresis and sufficient dilution of the urine (the same advice applies to patients at risk of other types of lithiasis)

-Choose the minerality of one’s drinking water based on one’s dairy consumption.

Thus, if:

•  the subject likes dairy products and he or she consumes enough to meet the recommended calcium intake, it is  recommended to drink a water that  has a low calcium content (Calcium < 150 mg/l)
• the subject has an insufficient calcium intake (< 1g/day), it will be advisable to drink water rich in calcium (>150 mg/l), being careful not to exceed the recommended daily amount
• the subject is hypercalciuric, he or she should consume water with a low calcium content

In any case, drinking sufficiently every day, and making sure to increase one’s fluid intake during hot weather , fever and diarrhoea, allows the lithiasic patient to reduce the risk of recurrences.

 To learn more about Daily water needs click here

References :

1. Daudon M, Panteix G, Sagnol I, Petit I. Caractéristiques épidémiologiques régionales de la lithiase urinaire en France. Feuillets de Biologie 2007; 48 (277): 45-51.

2. Trinchieri A, Coppi F, Montanari E, Del Nero A, Zanetti G, Pisani E. Increase in the Prevalence of Symptomatic Upper Urinary Tract Stones during the Last Ten Years. Eur Urol 2000; 37:23–5.

3. Bataille P. Quelle est la ration calcique optimale chez le sujet souffrant de lithiase calcique. Cah.Nutr.Diet, 40, Hors série 1, 2005

4. Liebman M, Chai W. Effect of dietary calcium on urinary oxalate excretion after oxalate loads. Am J Clin Nutr 1997; 65: 1453-9

5. Bataille P and coll. Diet, vitamine D and vertebral mineral density in hypercalciuric calcium stone formers. Calcif.Tissue Int, 1990, 46, 9-13

6. Melton L.J anad coll. Fracture risk among patients with urolithiasis: a population based cohort study. Kidney Int, 1998, 53, 459-464

7. Apports Nutritionnels Conseillés pour la Population Française. Ed Tec et Doc Lavoisier, 2001

8. Curhan G.C and coll. A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. N.Engl.J.Med, 1993, 328, 833-838.

9. Curhan G.C and coll. Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women. Ann. Inter.Med, 1997, 126, 497-504.

10. Taylor E.N and coll. Dietary factors and the risk of incident kidney stones in men: new insights after 14 years of follow-up. J.Am. Soc.Nephrol. 2004, 15, 3225-3232.

11. Curham GC, Willett WC, Rimm EB, Spiegelman D, Stampfer MJ. Prospective study of beverage use and the risk of kidney stones. Am J Epidemiol 1996; 143: 240

12. Domrongkitchaiporn S and coll. Schedule of taking calcium supplement and the risk of nephrolithiasis. Kidney Int, 2004, 65, 1835-1841.