Sabtu, 27 Desember 2008

Butter, Margarine and Heart Disease

Shortly after World War II, margarine replaced butter in the U.S. food supply. Margarine consumption exceeded butter in the 1950s. By 1975, we were eating one-fourth the amount of butter eaten in 1900 and ten times the amount of margarine. Margarine was made primarily of hydrogenated vegetable oils, as many still are today. This makes it one of our primary sources of trans fat. The consumption of trans fats from other sources also likely tracked...

Jumat, 26 Desember 2008

Leptin Resistance and Sugar

Leptin is a major hormone regulator of fat mass in vertebrates. It's a frequent topic on this blog because I believe it's central to overweight and modern metabolic disorders. Here's how it works. Leptin is secreted by fat tissue, and its blood levels are proportional to fat mass. The more fat tissue, the more leptin. Leptin reduces appetite, increases fat release from fat tissue and increases the metabolic rate. Normally, this creates a "feedback loop" that keeps fat mass within a fairly narrow range. Any increase in fat tissue causes...

Kamis, 25 Desember 2008

The Fundamentals

I heard an interview of Michael Pollan yesterday on Talk of the Nation. He made some important points about nutrition that bear repeating. He's fond of saying "don't eat anything your grandmother wouldn't recognize as food". That doesn't mean your grandmother specifically, but anyone's grandmother, whether she was Japanese, American or African. The point is that commercial food processing has taken us away from the foods, and traditional food preparation methods, on which our bodies evolved to thrive. At this point, we don't know enough about...

Minggu, 14 Desember 2008

U.S. Weight, Lifestyle and Diet Trends, 1970- 2007

For this post, I compiled statistics on U.S. weight, health and lifestyle trends, and graphed them as consistently as possible. They span the period from 1970 to 2007, during which the obesity rate doubled. The data come from the National Health and Nutrition Examination Survey (NHANES), the Behavioral Risk Factor Surveillance System (BRFSS), and the U.S. Department of Agriculture (USDA). Some of the graphs are incomplete, either because the data...

Sabtu, 13 Desember 2008

The Myth of the High-Protein Diet

The phrase "low-carbohydrate diet" is a no-no in some circles, because it implies that a diet is high in fat. Often, the euphemism "high-protein diet" is used to avoid the mental image of a stick of butter wrapped in bacon. It's purely a semantic game, because there is no such thing as a diet in which the majority of calories come from protein. The ability of the human body to metabolize protein ends at about 1/3 of calories (1, 2), and the long-term optimum may be lower still. Low-carbohydrate diets (yes, the ones that are highly effective...

Senin, 08 Desember 2008

Gluten Sensitivity: Celiac Disease is the Tip of the Iceberg

Celiac disease is a degeneration of the lining of the small intestine caused by a sensitivity to gluten. Gluten is the protein portion of wheat, rye, barley, and wheat relatives (spelt, kamut, emmer, einkorn and triticale). I found an interesting paper recently on the impact of celiac disease on nutrient status and bone density. Researchers compared 54 Northern Italian children with untreated celiac disease to 60 presumably healthy children. The celiac patients had extremely poor vitamin D status, with a deficiency rate of 35.18% compared to...

Sabtu, 06 Desember 2008

Peripheral vs. Ectopic Fat

I went to an interesting presentation the other day by Dr. George Ioannou of the University of Washington, on obesity and liver disease. He made an interesting distinction between the health effects of two types of body fat. The first is called subcutaneous fat (or peripheral fat). It accumulates right under the skin and is evenly distributed over the body's surface area, including extremities. The second is called ectopic fat. Ectopic means "not where it's supposed to be". It accumulates in the abdominal region (beer belly), the liver, muscle...

Rabu, 03 Desember 2008

Polyunsaturated Fat Intake: What About Humans?

Now we know how to raise a healthy pig or rat: balance omega-6 linoleic acid (LA) and omega-3 alpha-linolenic acid (LNA) and keep both relatively low. LA and LNA are the most basic (and shortest) forms of omega-6 and omega-3 fats. They are the only fats the body can't make on its own. They're found in plant foods, and animal foods to a lesser extent. Animals convert them to longer-chain fats like arachidonic acid (AA; omega-6), EPA (omega-3) and DHA (omega-3). These long-chain, animal PUFA are involved in a dizzying array of cellular processes....