How much do we need to drink?

Whether spring-sourced, sparkling, flavored, or simply out of the tap, water seems to have become the beverage de rigueur these days.  And for good reason----water constitutes about 60% of our body weight and is essential for most bodily functions. Taking in enough fluids each day is highly important since inadequate intake, leading to dehydration, can have serious medical consequences.

How much water do we need?   Many people have heard of the recommendation that we should consume "8 ounces of water, 8 times a day".  However, in a report published in 2002, noted physiologist Heniz Valtin researched this question and found no scientific evidence to support this "8 x 8" recommendation.  His evidence showed that healthy bodies do a remarkable job at self-regulating their fluid balance and that the "8 x 8" recommendation may in some cases be excessive. This position was echoed by a 2004 report from the Institute of Medicine (IOM) who stated that "the vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide."  The IOM did set general recommendations of total water intake at 2.7 liters (91 ounces) for women and 3.7 liters (125 ounces daily) for men.

Do beverages other than water count toward daily fluid requirements?  Dr. Valtin's research found that moderate consumption of caffeinated and alcoholic beverages could count toward daily fluid requirements.  Additionally, since approximately 20% of our water intake
comes from food, those with high water content such as watermelon, broccoli, lettuce and yogurt also contribute to our daily requirements.
   
Are there situations where more than the "8 x 8" recommendation applies?  It should be noted that the recommendation to let "thirst be your guide" applies primarily to healthy, sedentary adults living in a temperate environment.  There are a number of circumstances in which our fluid requirements increase significantly.  Examples of this are working in a hot/humid environment, exercising for a prolonged period of time, or in association with certain illnesses.  For short bouts of exercise, this may just be an extra 1-2 cups of water, but for more intense exercise lasting an hour or more, regular intake may be required to avoid dehydration.  Depending on the ambient temperature, this usually means taking in 2 to 3 cups an hour.  With strenuous athletic activity lasting several hours, or if working in the heat, a sports drink (e.g. Gatorade, Powerade, others) may provide the additional benefit of replacing electrolytes lost in sweat.  Illnesses, such as fever, vomiting and diarrhea, cause your body to lose additional fluids. In these cases you should drink more water and may even need an oral rehydration solution, such as Pedialyte.

The average urine output for adults is 1.5 liters a day and 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 could well be the origin of the "8 x 8" recommendation. In any case, it appears that if you drink enough fluid so that you rarely feel thirsty, intake is probably adequate without having to count your cups.

Sources for article: 
Water: How much should you drink every day? from Mayo Foundation for Medical Education and Research
'Drink at least eight glasses of water a day.' Really? Is there scientific evidence for "8 x 8"? from the American Journal of Physiology

If you have any questions about how much water we need, please log into your account and send us your question. We are here to help.

Kent Davidson MD - Health Tip Content Editor
Reviewed and Approved by Charles W. Smith MD, Medical Director on 6-29-2016

Tick Bites and Meat Allergy

People who live in the southern and central United States, areas of the country where bites from the lone-star tick (Amblyomma americanum) are common, are reported to be at risk of developing an allergy to red meat.  The allergy is thought to develop as a result of exposure to a carbohydrate called alpha-gal (galactose-α-1,3-galactose) that is transferred from the tick to humans via their bite.
   

Alpha-gal is present in several mammals (e.g., cows, pigs, deer, sheep, etc.) but is not naturally present in apes and humans.  Ordinarily, when meat from one of these sources is consumed by humans, the alpha-gal remains in the digestive tract without causing problems.  If alpha-gal is transferred to the blood stream of a human during a tick bite, however, the body recognizes the carbohydrate as a foreign substance and initiates an immune response.

During this immune response, antibodies (IgE) to alpha-gal are produced to protect the body from this carbohydrate which it perceives to be a threat.  IgE antibodies are one of 5 classes of antibodies produced in the body and the one most commonly involved in allergies and allergic reactions. With subsequent consumption of food containing alpha-gal, IgE antibodies are released which bind to the foreign carbohydrate and trigger the release of histamine and other chemicals causing an allergic reaction.

Symptoms of a meat allergy can include:

• Hives or skin rash
• Nausea, stomach cramps, indigestion, vomiting, diarrhea
• Stuffy/runny nose
• Sneezing
• Headaches
• Asthma
• Anaphylaxis, an allergic reaction that restricts breathing

Alpha-gal-related allergy symptoms characteristically occur 3 to 6 hours after eating red meat, rather than the more typical hour or less common to most other food allergies. A blood test to measure for the presence of alpha-gal IgE antibodies is available, however, this test has not been approved yet by the U.S. Food and Drug Administration and may not be covered by certain health insurance carriers.

At present, treatment of alpha-gal meat allergy involves avoidance of eating meat from mammals.  Should mild symptoms occur despite avoidance efforts, treatment with antihistamines or corticosteroids should help. Anaphylaxis, also known as "anaphylactic shock", is a true medical emergency and requires immediate treatment. Symptoms of anaphylaxis include swelling of the tongue and throat, constriction of the airways, a weak and rapid pulse, and dizziness or fainting. Treatment typically involves administration of oxygen, anti-histamines and injectable epinephrine.  People with meat allergy should consider carrying an epinephrine auto-injector (e.g. EpiPen) in case of a reaction.
 
Non-mammalian meat (fish, chicken, turkey, etc.) does not contain alpha-gal, but milk and some milk products have been suspected of triggering the allergic reaction.  Gelatin and protein powder with whey may also contain alpha-gal. Although most common in the southeastern U.S., alpha-gal meat allergy could occur in any area of the country where lone-star ticks are present.  Other ticks, including the European Castor Bean Tick and the Paralysis Tick in Australia have also been implicated in the development of meat allergy.

Sources for article:
Researchers Tie Tick Bites to Serious Red Meat Allergy from Medscape
Meat Allergy from the American College of Allergy, Asthma & Immunology

If you have any questions about tick bites, please log into your account and send us your question. We are here to help

Kent Davidson MD - Health Tip Content Editor
Reviewed and Approved by Charles W. Smith MD, Medical Director on 6-22-2016.

Bursitis, not just a geriatric problem

Many people have heard of the term "bursitis", but few know what a bursa, the structure that is affected in bursitis, actually is.  In the body there are over 150 bursae (the plural of bursa).  A bursa is a small jelly-like sac, which serves as a cushion to decrease pressure between two adjacent structures.  For example, when a tendon slides against a bone in the process of moving a joint, a bursa helps to decreases the friction between these two structures. If a bursa becomes inflamed, a painful condition known as bursitis develops. Let's look at why bursitis may occur and at some of the most common types of bursitis
 .

What causes bursitis?  Bursitis is usually the result of an overuse or a traumatic injury. Repetitive movements, such as throwing a ball, kneeling for prolonged periods, or running, are example of activities that can produce overuse injuries. Trauma, such as a blow to an area of the body overlying a bursa, can also lead to the development of inflammation within the bursa sac.
 
Which bursae are most commonly affected?  Fortunately, only a few of the bursae in the body are likely to become inflamed. These include the bursa at the side of the hip joint (trochanteric bursa), the one on top of the shoulder (subacromial bursa), a bursa on the front of the kneecap (pre-patellar bursa) and the bursa at the tip of the elbow (olecranon bursa).

Trochanteric bursitis is a common problem that causes pain over the outside of the upper thigh. The trochanteric bursa rests between the bony prominence on the side of the upper hip (the greater trochanter) and a tendon that passes over this bone. Someone with trochanteric bursitis usually reports having hip pain at night, particularly when lying on the affected side. Pain may also be noticed at the outside of the upper hip when getting up from a chair or after prolonged walking, stair climbing, or squatting.

Subacrominal bursitis affects the shoulder, causing pain with movement such as reaching overhead or behind the back. It is part of a broader condition known as "impingement syndrome", one of the most common causes for shoulder pain. With impingement, "pinching" of the rotator cuff tendons and bursa occurs between the humerus (upper arm bone) and the bony arch (acromion) that is situated above. While it is more likely to develop in individuals over the age of 40, it is far from a geriatric problem.  Sports activities, including tennis, swimming, and baseball, can all cause subacrominal bursitis.  Work-related activities, such as overhead assembly work, can also trigger this type of bursitis.

Pre-patellar bursitis affects the bursa on the front of the knee cap (patella). This bursitis is sometimes known as "housemaid's knee", since the repetitive pressure on the front of the knee from kneeling, as when scrubbing a floor, is a typical cause. Pre-patellar bursitis can also be caused by a direct blow or fall on the knee.  In pre-patellar bursitis a fluid filled lump is often visible over the front of the kneecap.

Olecranon bursitis is associated with marked swelling at the tip of the elbow.  Prolonged pressure to the tip of the elbow, as could occur in someone who drives for long distances with their elbow on an arm rest, is an example of an activity that could produce this type of bursitis.  A traumatic injury, such as striking the tip of the elbow in a fall, can also cause olecranon bursitis.

What is the treatment for bursitis?   While there are some differences in treatment among the various types of bursitis, a few treatment principles remain the same for all types. First a period of rest is necessary. This means avoiding activities that led to the development of the bursitis or those that aggravate the problem.   Next, anti-inflammatory medications (e.g. ibuprofen, naproxen, etc.) are typically recommended to help control the inflammation. Intermittent application of ice to the skin overlying the inflamed bursa can also help to diminish inflammation as well as serving to reduce pain. Other measures that can be used in treating bursitis include physical therapy modalities, stretching exercises, cortisone injections, and rarely surgery.

A special circumstance should be mentioned when treatment of bursitis becomes urgent. If the skin overlying the bursa becomes broken, such as with an insect bite or a scrape, bacteria may get inside the bursa and cause an infection. Infected bursae can become markedly swollen with redness and swelling of the overlying skin. Surgery, to incise the bursa and drain accumulated pus, along with antibiotic treatment, is usually necessary.

So, if the doctor tells you that you have bursitis, don't feel like you are necessarily "over the hill". Bursitis is almost as common among younger, active individuals as it is in older folks.

Sources for article:
Hip bursitis from OrthoInfo
Bursitis and Tendinitis from the National Institutes of Health