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Side Effects of Tonalin

author image Janet Renee, MS, RD
Janet Renee is a clinical dietitian with a special interest in weight management, sports dietetics, medical nutrition therapy and diet trends. She earned her Master of Science in nutrition from the University of Chicago and has contributed to health and wellness magazines, including Prevention, Self, Shape and Cooking Light.
Side Effects of Tonalin
Doctor speaking with patient in office. Photo Credit: XiXinXing/XiXinXing/Getty Images

Because supplements may cause unwanted side effects, it's crucial to be aware of potential adverse reactions so you can make an informed decision. The same is true for Tonalin, a dietary supplement meant to reduce body fat. Tonalin is a brand of conjugated linoleic acid -- a type of fat found primarily in beef and dairy. There is evidence to support its effectiveness, but there are also side effects for you to know.

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Reduces Body Fat

CLA reduced body fat in healthy overweight adults in a long-term study reported in the American Journal of Clinical Nutrition in June 2004. The study involved male and female participants with a body mass index of 25 to 30. BMI is a measurement of body fat. CLA caused a decrease in body fat and an increase in lean mass over the course of the 6-month study. These results support short-term studies that show CLA reduces body fat in humans, according to the authors.

Adversely Affects Cholesterol

A National Institutes of Health Office of Dietary Supplement presentation highlighted side effects on cholesterol. It reported that studies, such as the one reported by the American Journal of Clinical Nutrition found that CLA negatively affected cholesterol. CLA caused an increase in low-density lipoprotein -- a bad form of cholesterol and a decrease in high-density lipoprotein, a good blood cholesterol. These effects are likely temporary and may go away after you stop taking the supplement.

Affects Insulin Regulation

CLA may increase blood sugar levels and decrease insulin sensitivity, according to the NIH presentation. Insulin is a hormone that plays a significant role in regulating blood sugar. You may not experience this side effect however, because in some people CLA improves insulin sensitivity, according to a study published in the May 2004 issue of the journal Medicine and Science in Sports and Medicine. Before taking Tonalin, consult with your doctor if you have insulin resistance or diabetes.

Other Side Effects

CLA may decrease leptin in some people, according to the NIH presentation. Leptin is a food-regulating hormone that promotes a feeling a fullness, letting your brain know that you've had enough to eat. Get permission from your doctor before taking this supplement if you're prescribed medication. There is a report of CLA potentially interacting with medication used to treat ADHD. The subject reported experiencing rapid heart beat, nausea, increased hunger and trouble falling asleep, according to the NIH presentation. Mild side effects of Tonalin include fatigue and digestive issues such as indigestion and diarrhea.

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