Conjugated linoleic acid (CLA) refers to a family of many isomers of linoleic acid (at least 13 are reported), which are found primarily in the meat and dairy products of ruminants. As implied by the name, the double bonds of CLAs are conjugated.
Tuesday, September 4, 2007
Conjugated linoleic acid is a trans fat, though some researchers claim that it is not harmful in the same fashion as other trans fatty acids, but rather is beneficial.  CLA is a conjugated system, and in the United States, trans linkages in a conjugated system are not counted as trans fat for the purposes of nutritional regulations and labeling. Unlike most trans fatty acids found in the human diet, CLA occurs naturally, produced by microorganisms in the fore-stomach of ruminants. Non-ruminants, such as humans, may be able to produce some isomers of CLA from non-conjugated ruminant fats. One such example is vaccenic acid, which could be converted to CLA by delta-9-desaturase.
CLA comes in two isomers: the c9,t11 isomer (rumenic acid) which appears responsible for improving muscle growth, and the t10,c12 isomer which primarily prevents lipogenesis (storage of fat in adipose tissue). Most supplements sold in stores contain a 50/50 mix of both isomers.
Various antioxidant and anti-tumor properties have been attributed to CLA, and studies on mice and rats show promising results in reducing mammary, skin, and colon tumor growth; however, it is suspected that sufficient concentrations to achieve anti-inflammatory effects within human tissues may not be attainable via oral consumption. 
Many studies on CLA in humans show a tendency for reduced body fat, particularly abdominal fat, changes in serum total lipids and decreased whole body glucose uptake. The maximum reduction in body fat mass was achieved with a 3.4 g daily dose. CLA supplementation has, however, been shown to increase C-reactive protein levels and to induce oxidative stress and to reduce insulin sensitivity and increase lipid peroxidation.
CAS registry number: 2420-56-6, Molecular Formula: C18H32O2
Publicada por blogger em 4:54 AM
Monday, September 3, 2007
Eating less calories and increasing exercise are both just as good to help people lose weight. Research has shown that people who only eat less, and people who exercise more but eat the same amount of food a they always used to, lose the same amount of weight. The research also shakes some of the very firm beliefs used in the diet industry stating that there are certain ways to lose fat and boost the metabolism by exercising more. This is simply not true. Adding muscle mass to the body does not necessarily help people to shed the pounds any faster and adding muscle weight may even increase body weight.
According to Dr. Eric Ravussin of Pennington Biomedical Research Centre, which is part of the Louisiana State University in Baton Rouge, losing weight is all down to calories. As long as the energy deficit stays the same, the amount of body weight, body fat weight, and even abdominal fat will all steadily decrease in a very similar way.
For this research procedure 24 people were tested. Twelve people at a low calorie diet and 12 people simply dieted and they also exercised five times a week during six months.
The people dieting ate 25 percent less than they would usually do and the exercisers actively reduced their calorie food intake by over twelve percent. They increased their physical activities to make sure that they would lose an extra 12.5 percent in calories.
All the volunteers in the test groups lost around 10 percent of their first body weight and nearly 25% of their body fat mass. More importantly they also lost over 25% of their visceral fat. Visceral fat is a type of fat packed in between the internal organs. Basically this research shows dieters that there is no such thing as losing weight in one spot.
Publicada por blogger em 7:28 AM