Thursday, July 31, 2014

The Dangers of Dehydration

"Water is the driving force in nature."
--Leonardo da Vinci

Water constitutes up to 60% of the human adult body.  This water serves a number of important functions including:                     
  • Helping to regulate body temperature through sweating
  • Assisting in flushing waste out of the body
  • Carrying nutrients and oxygen to the body’s cells
  • Moistening tissues in the eyes, nose, and mouth
  • Lubricating and cushioning joints

In fact, nearly all of the major systems in the body depend on the availability of water.  The body has limited capacity for storing water so a continuous supply is required to maintain these functions. When you use or lose more water than you are taking in, dehydration can develop. Some of the causes for dehydration include exercising in the heat, fever, vomiting or diarrhea, and not drinking adequate amounts.

Signs of dehydration:   Thirst, the physiological urge to drink water, is a signal that the body is becoming dehydrated. Other signs of mild to moderate hydration include dry or sticky mouth, dark yellow urine, headache and muscle cramps.  Severe dehydration may be associated with absence of urination, rapid heartbeat, dizziness, confusion, rapid respirations, and even loss of consciousness.

Dangers of dehydration:   Dehydration can lead to serious complications, including:
  • Heat injury.  Dehydration coupled with high ambient temperatures can lead to heat injury. This can range in severity from mild heat cramps to its most severe form, heatstroke.
  • Hypovolemic shock.  Since water is the major constituent of blood, dehydration can reduce the volume of circulating blood. The resulting hypovolemia (low blood volume) can the cause a severe drop in blood pressure and oxygen being delivered to the body, a condition known as “shock”.
  • Kidney failure.  With dehydration and reduced blood flow, the kidneys are unable to remove excess fluids and waste from your blood.  This can lead to the accumulation of waste products such as creatinine and urea nitrogen in the body.
  • Kidney Stones. Higher temperatures contribute to dehydration, which leads to an increased concentration of calcium and other minerals in the urine that promote the growth of kidney stones.
  • Coma or death. If not addressed promptly with measures to rehydrate, severe dehydration can be fatal.
Treating dehydration:  Fluid replacement is the treatment for dehydration.  In less severe cases this can be done by replacing fluid by mouth. In more severe cases, intravenous (IV) fluids may be required.

Staying hydrated:  The average urine output for adults is 1.5 liters a day. Additionally, people lose almost a liter of water a day through breathing, sweating and bowel movements.  Since approximately 20% of our daily fluid requirement is met through the foods we eat, this leaves about 2 liters (or about 8 cups) to get through drinking water and other fluids.  This calculation may have led to the recommendation that we need to drink “8 ounces of water (one cup), 8 times a day”.  Does this mean that the water requirement for someone working and living in an air conditioned environment is the same as that of a physical laborer working outdoors during the summer?  Of course not---individual water requirements are highly variable, depending on a number of factors such as the ambient temperature, activity level and state of health.

For healthy adults in a temperate climate without the additional fluid requirements brought about by exercise, the answer appears to be “let thirst be your guide”.  If you drink enough fluid so that you rarely feel thirsty, your fluid intake is most likely adequate without having to count your cups.

With the increased sweating that occur during exercise or working in a hot environment, you’ll need more fluid to keep your body hydrated. For short bouts of exercise, this may just be an extra 1-2 cups but for more intense exercise lasting an hour or more, regular intake is necessary to avoid dehydration.  Depending on the ambient temperature, this usually means taking in 2 to 3 cups per hour.  With strenuous athletic activity lasting several hours, or if working in the heat, a sports drink containing sodium may even be better than plain water in helping to maintain electrolyte balance.

Thursday, July 24, 2014

Dietary Supplements vs. FDA-approved medications

"One man's meat is another man's poison…" - Lucretius, 1st century BC


Recently, a friend of mine ended up in the emergency department a few days after starting a dietary supplement that she assumed was safe since it could be purchased without a prescription. What she didn’t realize is that many supplements, just like prescription medications, have side effects and can interact with other medications.  Fortunately, she recovered completely, but is now much more careful about taking these products. Exactly what is a dietary supplement and how does it differ from a FDA-approved medication?
     
 In response to popular demand, the Food and Drug Administration (FDA) may have “opened a can of worms”, allowing a profusion of questionable health-related products to hit the market. The 1994 Dietary Supplement Health and Education Act (DSHEA) passed in part because "millions of consumers believe dietary supplements may help to augment daily diets and provide health benefits." This resulted in a different set of regulations governing dietary supplements than those covering conventional foods and drug products (prescription and over-the-counter).
 
 The DSHEA established a formal definition of "dietary supplement" using several criteria. Chiefly, a supplement is considered to be "a product (other than tobacco) that is intended to supplement the diet that bears or contains one or more of the following dietary ingredients: a vitamin, a mineral, an herb or other botanical, an amino acid, a dietary substance for use by man to supplement the diet..."
  
Nowhere in the defining criteria, however, is there anything that relates to the effectiveness of the supplement. In fact, the FDA specifically states that "claims may not be made about the use of a dietary supplement to prevent, mitigate, treat, or cure a specific disease." Manufacturers may describe the supplement's effects on "structure or function" of the body or the "well-being" achieved by consuming the dietary ingredient, but very little proof is required to back up these claims. The manufacturers are simply required to attest that their statements are truthful, which seems uncomfortably similar to allowing the fox to guard the hen house.
 
Even the provisions in the act that try to assure the safety of dietary supplements are dubious. Under DSHEA, a dietary supplement is considered to be "adulterated" if it or one of its ingredients presents "a significant or unreasonable risk of illness or injury." Although the Secretary of Health and Human Services "may declare that a dietary supplement poses an imminent hazard to public health or safety" and have it removed from the market, the mechanism by which adverse effects or abuse potential is monitored is unclear. And guess who is responsible for ensuring that its products are safe and properly labeled---the manufacturer, of course.
 
This is not to say that all dietary supplements are ineffective or unsafe. Many supplements (herbal products, multivitamins and mineral supplements, etc.) have excellent safety records and are used successfully by millions of consumers. Unlike drug products that must be proven safe and effective for their intended use before marketing, however, there are no provisions in the law for FDA to "approve" dietary supplements for safety or effectiveness before they reach the consumer. Also unlike drug products, manufacturers and distributors of dietary supplements are not currently required by law to record, investigate or forward to the FDA any reports they receive of injuries or illnesses that may be related to the use of their products.
 
So the next time that you're tempted to purchase a dietary supplement that claims to restore hair growth, dissolve fat from your hips, give you a six-pack abdomen or a myriad of other fantastic results, just remember that very little proof of their effectiveness or safety is required before they hit the market. Caveat Emptor (Buyer Beware)!

Friday, July 11, 2014

Is antibacterial soap really necessary?

Every day, millions of people use soaps and body washes that are labeled as being antibacterial or antimicrobial.  Much of the proliferation of these products appears to be due to the marketing efforts of their manufacturers. Makers of these products have convinced us that using these products demonstrates concern for our family’s welfare as well as our own personal health.

Despite their widespread use, there is very little evidence to support the use of these products over the time-honored practice of washing with soap and water.  Recently, the Food and Drug Administration (FDA) has proposed a ruling that would require manufacturers of these products to demonstrate their safety and effectiveness. If adopted, products that are not shown to be superior to non-antibacterial soaps in preventing human illness or reducing infection will be taken off the market. The proposed rule covers only household soaps and body washes and does not apply to hand sanitizers or antibacterial soaps used in the health care setting.

What makes a soap antibacterial?  Most commonly, soaps labeled “antibacterial” or “antimicrobial” contain the chemicals triclosan or triclocarban. These are added to the soap in an effort to reduce or prevent bacterial contamination.  Although they have not been confirmed to be hazardous to humans, recent studies have brought up concerns regarding exposure to these chemicals.

What are the risks of exposure to triclosan?  The primary concerns regarding the addition of triclosan to common soap relate to: 1) alteration in hormone levels in animal models and 2) the possibility that use of triclosan could contribute to the development of “super bugs”, bacteria that are resistant to antibiotics. In regard to the first issue, some studies have shown that animals exposed to triclosan have developed reduced levels of thyroid hormone and testosterone. The concern regarding the development of resistant bacteria comes from the assumption that antimicrobial chemicals could act much in the same way as antibiotics. It is well known that bacteria exposed to an antibiotic can undergo genetic changes that reduce their susceptibility to the effects of that antibiotic. While triclosan has never conclusively been shown to cause the development of antibiotic resistant bacteria, the potential for the emergence of “super bugs” remains a serious concern.

Is there evidence to support the use of triclosan at all? In some instances, triclosan has been shown to be uniquely beneficial. For example, the manufacturers of a popular brand of toothpaste were able to convincingly demonstrate to the FDA that the addition of triclosan was effective in preventing gum infections.  Evidence is currently lacking, however, regarding the benefits of triclosan in personal cleansing.