Low-Carb Research Update

“What about that recent study in American Journal of Clinical Nutrition…?”

As much as possible, I base my nutrition and medical recommendations on science-based research published in the medical literature.  Medical textbooks can be very helpful, but they aren’t as up-to-date as the medical journals.

In the early 2000s, a flurry of research reports demonstrated that very-low-carb eating (as in Dr. Atkins New Diet Revolution) was safe and effective for short-term weight management and control of diabetes.  I was still concerned back then about the long-term safety of the high fat content of Atkins.  But 80 hours of literature review in 2009 allowed me to embrace low-carbohydrate eating as a logical and viable option for many of my patients.  The evidence convinced me that the high fat content (saturated or otherwise) of many low-carb diets was little to worry about over the long run.

By the way, have you noticed some of the celebrities jumping on the low-carb weight-management bandwagon lately?  Sharon Osbourne, Drew Carey, and Alec Baldwin, to name a few.

My primary nutrition interests are low-carb eating, the Mediterranean diet, and the paleo diet.  I’m careful to stay up-to-date with the pertinent scientific research.  I’d like to share with you some of the pertinent research findings of the last few years.

Low-Carb Diets

• Low-carb diets reduce weight, reduce blood pressure, lower triglyceride levels (a healthy move), and raise HDL cholesterol (another good trend).  These improvements should help reduce your risk of heart disease.  (In the journal Obesity Reviews, 2012.)
• Dietary fat, including saturated fat, is not a cause of vascular disease such as heart attacks and atherosclerosis (hardening of the arteries).  (Multiple research reports.)
• If you’re overweight and replace two sugary drinks a day with diet soda or water, you’ll lose about four pounds over the next six months.  (American Journal of Clinical Nutrition, 2012.)
• United States residents obtain 40% of total calories from grains and added sugars.  Most developed countries are similar.  Dr. Stephan Guyenet notes that U.S. sugar consumption increased steadily “…from 6.3 pounds [2.9 kg] per person per year in 1822 to 107.7 pounds [50 kg] per person in 1999.  Wrap your brain around this: in 1822 we ate the amount of added sugar in one 12-ounce can of soda every five days, while today we eat that much sugar every seven hours.”
• A very-low-carb diet improves the memory of those with age-related mild cognitive impairment. Mild cognitive impairment is a precursor to dementia.  (University of Cincinnati, 2012.)
• High-carbohydrate and sugar-rich diets greatly raise the risk of mild cognitive impairment in the elderly. (Mayo Clinic study published in the Journal of Alzheimers’ Disease, 2012.)
• Compared to obese low-fat dieters, low-carb dieters lose twice as much fat weight.  (University of Cincinnati, 2011.)
• Diets low in sugar and refined starches are linked to lower risk of age-related macular degeneration in women.  Macular degeneration is a major cause of blindness.  (University of Wisconsin, 2011.)
• A ketogenic (very-low-carb) Mediterranean diet cures metabolic syndrome (Journal of Medicinal Food, 2011.)
• For type 2 diabetics, replacing a daily muffin (high-carb) with two ounces (60 g) of nuts (low-carb) improves blood sugar control and reduces LDL cholesterol (the “bad” cholesterol). (Diabetes Care, 2011.)
• For those afflicted with fatty liver, a low-carb diet beats a low-fat diet for management. (American Journal of Clinical Nutrition, 2011.)
• For weight loss, the American Diabetes Association has endorsed low-carb (under 130 g/day) and Mediterranean diets, for use up to two years. (Diabetes Care, 2011.)
• High-carbohydrate eating doubles the risk of heart disease (coronary artery disease) in women.  (Archives of Internal Medicine, 2010.)
• One criticism of low-carb diets is that they may be high in protein, which in turn may cause bone thinning (osteoporosis).  A 2010 study shows this is not a problem, at least in women.  Men were not studied.  (American Journal of Clinical Nutrition.)
• High-carbohydrate eating increases the risk of developing type 2 diabetes (American Journal of Clinical Nutrition, 2010.)
• Obesity in U.S. children tripled from 1980 to 2000, rising to 17% of all children.  A low-carb, high-protein diet is safe and effective for obese adolescents.  (American Journal of Clinical Nutrition, 2010.)

Mediterranean Diet

The traditional Mediterranean diet is well established as a healthy way of eating despite being relatively high in carbohydrate: 50 to 60% of total calories.  It’s known to prolong life span while reducing rates of heart disease, cancer, strokes, diabetes, and dementia.  The Mediterranean diet is rich in fresh fruits, vegetables, nuts and seeds, olive oil, whole grain bread, fish, and judicious amounts of wine, while incorporating relatively little meat.  It deserves your serious consideration.  I keep abreast of the latest scientific literature on this diet.

• Olive oil is linked to longer life span and reduced heart disease.  (American Journal of Clinical Nutrition, 2012.)
• Olive oil is associated with reduced stroke risk.  (Neurology, 2012).
• The Mediterranean diet reduces risk of sudden cardiac death in women.  (Journal of the American Medical Association, 2011.)
• The Mediterranean diet is linked to fewer strokes visible by MRI scanning.  (Annals of Neurology, 2011.)
• It reduces the symptoms of asthma in children.  (Journal of the American Dietetic Association, 2011.)
• Compared to low-fat eating, it reduces the incidence of type 2 diabetes by 50% in middle-aged and older folks.  (Diabetes Care, 2010.)
•  A review of all available well-designed studies on the Mediterranean diet confirms that it reduces risk of death, decreases heart disease, and reduces rates of cancer, dementia, Parkinson’s disease, stroke, and mild cognitive impairment.  (American Journal of Clinical Nutrition, 2010.)
• It reduces the risk of breast cancer.  (American Journal of Clinical Nutrition, 2010.)
• The Mediterranean diet reduces Alzheimer’s disease.   (New York residents, Archives of Neurology, 2010).
• It slows the rate of age-related mental decline.  (Chicago residents, American Journal of Clinical Nutrition, 2010.)
• In patients already diagnosed with heart disease, the Mediterranean diet prevents future heart-related events and preserves heart function.  (American Journal of Clinical Nutrition, 2010.)

Clearly, low-carb and Mediterranean-style eating have much to recommend them.  Low-carb eating is particularly useful for weight loss and management, and control of diabetes, prediabetes, and metabolic syndrome.  Long-term health effects of low-carb eating are less well established.  That’s where the Mediterranean diet shines.  That’s why I ask many of my patients to combine both approaches: low-carb and Mediterranean.  Note that several components of the Mediterranean diet are inherently low-carb: olive oil, nuts and seeds, fish, some wines, and many fruits and vegetables.  These items easily fit into a low-carb lifestyle and may yield the long-term health benefits of the Mediterranean diet.  If you’re interested, I’ve posted on the Internet a Low-Carb Mediterranean Diet that will get you started.

Steve Parker, M.D.

Disclaimer:  All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status.  Always consult your personal physician before making any dietary or exercise changes.