Friday, May 22, 2015

Does Metabolism Really Slow with Aging?

Metabolism comprises a number of biochemical processes that are necessary to maintain life.  One type of metabolism (catabolism) produces energy by breaking down complex molecules. The breakdown of carbohydrates during digestion is an example of a catabolic process.  The other type of metabolism (anabolism) is constructive, such as when muscle mass is increased. Anabolic processes consume rather than produce energy.

Effect of metabolism on body weight. The metabolic rate is the relative speed at which anabolism and catabolism are occurring.  In simple terms, body weight is a result of catabolism minus anabolism. If catabolism exceeds anabolism, more energy is produced that is being used.  When this happens, the excess energy produced is stored in the body in the form of fat or glycogen (the storage form of carbohydrates).   If anabolism exceeds catabolism, however, more energy is being “burned” than produced and weight loss occurs.
 
Fast vs. slow metabolism.  When someone is referred to as having a “fast metabolism”, the implication is that their body’s engine is highly efficient at burning calories. An example of this might be an active, growing adolescent who stays slim despite eating huge quantities of food.   Obese individuals, on the other hand, are often labelled as having “slow metabolism”. While this is usually inaccurate, these are the individuals that seem to gain weight in spite of eating “like a bird”.  There are only a few situations, such as having an underactive thyroid gland (hypothyroidism) in which metabolism is truly slowed down. Many people have the understanding that with aging, a slowing of metabolism occurs that results in an inevitable increase in fat stores and weight gain.

Effect of muscle and fat on metabolism. Muscle is a more metabolically active tissue than fat.  The more muscle that an individual has, the more energy (calories) is required to maintain that muscle. A bonus to having a higher percentage of muscle over fat is that while at rest (basal metabolism) muscle burns more calories than fat. The difference is relatively small, in the range of an additional 5 to 7 calories per pound of body weight per day, but over time this can add up significantly.  This makes losing weight and keeping it off easier for more active individuals.

What about supplements?  A number of non-prescription products claim to increase metabolism or fat burning.  While green tea has been shown, at least in one study, to have some slight fat oxidation potential, more often than not these products are a sham. In some cases, they contain ingredients with potentially harmful side effects. Recently, supplements containing the herb Acacia rigidula were removed from the market because of stimulant side effects increased heart rate and caused high blood pressure.
 
Effect on aging on metabolic rate.  Aging, primarily due to a reduction in activity level and increased caloric intake, often results in a loss of muscle mass and increased fat stores.  Since fat is less metabolically active than muscle, technically our metabolism does slow down with aging.  Coupled with this is evidence that as we age, our mitochondria, the tiny “energy factories” in our cells, slow down their function. There is also evidence, however, to indicate that a major slowing of metabolism associated with aging is not necessarily inevitable. Staying physically active and maintaining a healthy weight can help reduce this “slowing”. This is a classic example of “use it or lose it”---either we take the steps to keep our metabolism revved up or we concede to the effects of aging.

Thursday, May 14, 2015

Five Reasons you might feel better on a Gluten-Free Diet

The term “gluten-free” is increasingly being seen attached to foods in restaurants and grocery stores throughout the U.S.  Even food items such as bottled spring water, fruits and vegetables, and eggs are being labeled "gluten-free" without ever containing gluten to begin with.  With millions of Americans making a change to eating gluten-free products, what are some of the reasons that people might really benefit from this dietary practice?
   
1. Celiac disease---Celiac disease, affecting approximately 1% of the U.S. population, is an immune-based reaction to dietary gluten, a protein found in wheat, barley and rye.  This disease primarily affects the small intestine causing malabsorption symptoms including diarrhea, abdominal pain, and weight loss. It can also cause non-gastrointestinal problems including nutrient deficiencies, anemia, bone disease, and skin disorders.  There is a genetic predisposition for celiac disease with the condition being much more likely to occur in someone with a first-degree relative— parent, sibling, or child—diagnosed with the disease.  The diagnosis is suspected with a blood test for anti-tissue transglutaminase antibodies (tTGA) and confirmed by biopsies taken from an area of the small intestine (duodenum).  Celiac symptoms resolve with exclusion of gluten from the diet.

2. Non-celiac gluten sensitivity (NCGS) ---This recently described condition causes similar, although less severe, symptoms than celiac disease. By definition, symptoms of NCGS should resolve on a gluten-free diet.  Unlike celiac disease, an autoimmune basis for NCGS has not been identified, nor are abnormalities seen on blood testing or biopsies of the duodenum. Gastrointestinal symptoms including abdominal pain or cramping, increased gas, altered bowel habits, and bloating predominate in NCGS.  Many people with NCGS also attribute a number of non-gastrointestinal symptoms including “foggy mind”, depression, headaches, and chronic fatigue after eating gluten-containing foods.  With such a wide spectrum of symptoms and no confirmatory test available, NCGS may overlap with other conditions such as irritable bowel syndrome, wheat allergy or other food sensitivities. People with this condition seem to largely be responsible for the multi-billion dollar industry in gluten-free products that has developed over the past few years.

3. Wheat allergy---Wheat is a fairly common allergy-producing food. The specific allergens contained in wheat are mostly its protein constituents, including albumin, globulin, gliadin and gluten.  Wheat allergy most commonly affects children, but it can occur in adults also.  Allergic symptoms usually begin within minutes to a couple of hours after eating wheat and include hives, facial swelling, abdominal cramps, and wheezing. The most serious type of allergic reaction to wheat is called anaphylaxis, which can be a life threatening problem.  Anaphylaxis is characterized by extreme constriction of the airways and a drop in blood pressure that can lead to shock, and loss of consciousness.  Typically, there are no long term consequences following an allergic reaction, although a repeat exposure could trigger the same chain of events all over again.  Diagnosis of wheat allergy is primarily clinical (medical history, family history, food history), supported by appropriate laboratory tests, including a blood screen for allergens (RAST test) and/or skin prick-testing.   Avoidance of wheat products will prevent the symptoms of wheat allergy and is crucially important in someone with anaphylaxis to wheat.
   
4. Sensitivity to foods rich in FODMAPs---The acronym FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. FODMAPs are short-chained carbohydrates that are incompletely absorbed in the gastrointestinal tract and then fermented by gut bacteria. Those who are sensitive to FODMAPs display similar gastrointestinal symptoms (diarrhea, constipation, gas, bloating and/or cramping) to people who have non-celiac gluten sensitivity.  Wheat contains an oligosaccharide called fructan and those sensitive to FODMAPs have reported marked improvement on a gluten-free diet.  A better diet for those with this type of food sensitivity, however, may be a low-FODMAPs diet. This is a fairly restrictive diet that includes avoidance of a number of foods including honey, dairy products, garlic, onions, sugar-free sweeteners and certain fruits (prunes, plums, dates, cherries, apricots).  The Australian researcher who was the first to suspect the existence of non-celiac gluten sensitivity, upon further research, was lead to believe that FODMAP sensitivity was a more common cause for gastrointestinal symptoms than gluten sensitivity.

5. Placebo effect--- In a recent Consumer Reports survey of more than 1000 people, 63 percent of them thought that eating a gluten-free diet would provide health benefits, and one third reported buying gluten-free products or avoiding gluten. Some of the benefits they believed to be associated with gluten-avoidance included improved digestion, weight loss, and increased energy.  None of these health benefits, however, have been substantiated scientifically.  Nevertheless, the number of gluten-free products on the market is exploding based to some degree on people “feeling better”, rather than relieving any particular symptoms. And while eating gluten-free would seem to be harmless, there may actually be a down side.  In order to make up for the loss of flavor provided by wheat, rye and barley, many gluten-free products substitute increased amounts of fat, salt and sugar.  Also, food manufacturers may also be taking advantage of consumers by charging more for their gluten-free products while this trend is booming.

Celiac disease and wheat allergy are serious medical conditions in which avoidance of wheat or gluten-containing foods is not only important but may be life-saving.  It should not be assumed that wheat or gluten is a problem in one’s diet, however, based on popular press or other’s perceptions. With the overlap in symptoms in irritable bowel syndrome, FODMAP sensitivity and non-celiac gluten sensitivity, it makes sense to try to determine the exact cause for symptoms. In that way, the most appropriate dietary measures, which in some cases does involve elimination of gluten-containing foods, can be made.

Friday, May 8, 2015

Reducing Your Risk of Melanoma

Skin cancer is the most common form of cancer in the United States, occurring in over 3.5 million people each year.  Three of the most common types of skin cancer are squamous cell carcinoma, basal cell carcinoma, and melanoma.   Of these, the least common, but most serious is melanoma. 


What is melanoma?---Melanoma is a cancer of the pigment producing cells (melanocytes)  of the skin. The great majority of melanomas can be attributed to exposure to ultraviolet (UV) radiation from the sun.  Melanoma begins on the surface of the skin but over time can extend deeper and in some cases, even spread throughout the body.

Who gets melanoma?---The factors that increase your risk of developing melanoma include:
  • Fair skin
  • Severe or multiple sunburns
  • A close relative, e.g. parent, child or sibling, who has had a melanoma
  • Unusual (atypical) moles
  • More than 50 moles
  • Weakened immune system, e.g. HIV/AIDS  or organ transplant
The National Cancer Institute has developed a Melanoma Risk Assessment Tool to assess your personal risk of developing melanoma.  

Recognizing melanoma---Signs indicating that a skin lesion is melanoma include a new pigmented area on the skin, or a change in size, shape or color of an existing mole. The ABCDE rule is another way to recognize melanomas:
  • Asymmetry: A mole that has an irregular shape, or the shape of one half does not match the other half.
  • Border: The edges are irregular, blurred, rough, or notched in outline.
  • Color: Most moles are evenly colored, e.g. brown, black, or tan.  Changes in the shade or distribution of color throughout the mole can signal melanoma.
  • Diameter: Moles larger than ¼ inch (6 mm, the size of a pencil eraser) across are suspicious.
  • Evolving: The mole has changed over the past few weeks or months
Treatment of Melanoma---Melanoma is the most serious type of skin cancer.  Early recognition and treatment leads to better outcomes. Treatment in almost all cases begins with surgical excision, typically including a margin of apparently normal skin to insure that the lesion is removed entirely. Beyond surgical excision, treatment depends on the “stage” or extent of involvement of the cancer.  In the more advanced stages, the tumor can invade deeply, spread to lymph nodes, or even metastasize to other areas of the body.  For the least serious type of melanoma skin cancers (Stage 1), wide surgical excision may be all the treatment that is necessary. The outcome of treatment in these cases may be enhanced by using the Mohs technique.  For higher stages, treatment may include chemotherapy, radiation therapy, immunotherapy, and targeted therapy.  An example of targeted therapy involves the use of a drug, e.g. vemurafenib (Zelboraf) that attacks certain proteins in the tumor, leading to its destruction. While most Stage 1 melanoma patients can be cured, the 5-year survival rate for a Stage 4 melanoma patient is only about 15% to 20%.

Reducing the risk of developing melanoma---The development of most types of skin cancer is directly related to damage from exposure to ultraviolet (UV) radiation from the sun.  Here are some suggestions for minimizing exposure to these harmful rays:
  • Limit your exposure to ultraviolet (UV) rays.  Avoid being in the sun during the peak hours for UV exposure between 10 AM and 4PM. Don’t forget that snow and water can concentrate the sun’s rays and increase the risk of burning.
  • If sun exposure is unavoidable, use a broad spectrum sunscreen that is effective against UVA and UVB radiation with a SPF of 30 or higher.  This may be required year round, not just in the summer.
  • For extra protection wear long sleeves and long pants and a wide-brimmed hat. Wraparound sunglasses help to protect the skin around the eyes.
  • Avoid tanning beds or lights.  Despite claims of tanning bed companies and booths, the radiation (predominantly UVA) used in tanning lights increases the risk of developing skin cancer.  Exposure to tanning lights has been linked with an increased risk of melanoma, especially if it is started before a person is 30.
  • Pay attention to your own skin.  Any suspicious lesion should be brought to the attention of your primary care doctor or a dermatologist.  Melanomas can develop even in areas of the skin not exposed to the sun.
Regular examination of the skin, by a physician or by self-examination, is the key to identifying skin cancers in their earliest stages.  With summer approaching and many people spending more time in the outdoors, particular attention to should be given to avoiding sun exposure in order to reduce the risk of developing melanoma or other skin cancers.