The protein supplements you should avoid, and why they're bad for you

Charles Krupa/AP
Originally Published: 

Protein supplements are a quick and easy way to reach your daily protein needs, especially if you're looking to build muscle or if protein is lacking in your diet. But supplements do not have to be proven to be safe to the Food and Drug Administration before they're marketed. Some protein supplements may contain ingredients hard on the digestive system, indirectly lead to weight gain or have potentially detrimental effects on health. 

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Here are some of the ingredients in protein supplements (both dairy and non-dairy) you may want to watch out for.

Soy protein: Soy, in general, is hard on the digestive system, let alone soy-based protein powders. Moreover, 93% of soy in the U.S. is genetically modified, according to Nutritional Weight & Wellness

High consumption of soy can mess with the thyroid and potentially increase the risk of breast cancer, though studies haven't outwardly proven that yet.

Vegan protein supplement brand Vega offers a solid alternative to soy protein with protein powders made from pea protein. 

Charles Krupa/AP

Dairy protein supplements: Both whey and casein dairy protein supplements, two of the most popular, are made up of milk protein and can cause digestive issues, including constipation and diarrhea, for those with lactose intolerance.

Casein is a dairy protein that, unlike whey protein, usually contains whole milk powder that can lead to heavier weight gain and bulking. Casein is recommended for those really looking to buff up. 

Artificial Sweeteners: Protein powders may contain sucralose (Splenda), acesulfame potassium (Sweet One) and artificial flavors. Studies suggest that artificial sweeteners can indirectly lead to weight gain as they perpetuate our sugar craving and dependence.