The promises are enticing. Whether you’re looking to shed unwanted pounds, get a quick energy jolt, build muscles or fight the aging process, some supplement makers are boosting protein drinks as a scientifically proven way to quickly achieve your goals.

But Consumer Reports’ investigation, including tests at an outside lab of 15 protein drinks, a review of government documents and interviews with health and fitness experts and consumers, found most people already get enough protein, and there are far better and cheaper ways to add more if it’s needed. Some protein drinks can even pose health risks over time, especially at a consumption level of three or more servings a day, due to the potential to consume harmful heavy metals and excessive protein. All drinks in CR’s tests had at least one sample containing one or more of the following contaminants: arsenic, cadmium, lead and mercury. Those metals can have toxic effects on several organs in the body.

For most drinks CR tested, levels of those contaminants were in the low to moderate range, when they could be detected at all. But with three of the products, consumers who have three servings daily could be exposed to levels that exceed the maxi-mum limits for one or two of those contaminants in dietary supplements proposed by the U. S. Pharmacopeia (USP), the federally recognized authority that sets voluntary standards for health products.

The amount of lead in a single daily serving of eight of the protein supplements CR tested would require that the products carry a warning in California. State legislation known as Proposition 65 mandates that manufacturers notify consumers when products contain toxic substances at levels the state says pose even a low cancer or reproductive risk.

But federal regulations do not generally require that protein drinks and other dietary supplements be tested before they are sold to ensure that they are safe, effective and free of contaminants.

CR purchased 15 protein powders and drinks mainly in the New York metro area or online and tested multiple samples of each for arsenic, cadmium, lead and mercury. The results showed a considerable range, but levels in three products were of particular concern:

• Three daily servings of the ready-to-drink liquid EAS Myoplex Original Rich Dark Chocolate Shake provide an average of 16.9 micrograms (mcg) of arsenic, exceeding the proposed USP limit of 15 mcg per day and an average of 5.1 mcg of cadmium, which is just above the USP limit of 5 mcg per day.

• The samples of Muscle Milk Chocolate powder contained all four heavy metals, and levels of three metals in the product were among the highest of all products tested by CR. Average cadmium levels of 5.6 mcg in three daily servings exceeded the USP limit of 5 mcg per day, and the average lead level of 13.5 mcg also topped the USP limit of 10 mcg per day. The average arsenic level of 12.2 mcg was approaching the USP limit of 15 mcg per day.

• Muscle Milk Vanilla Creme contained 12.2 mcg of lead in three daily servings, exceeding the lead limits, and 11.2 mcg of arsenic.

The CR investigation notes that cadmium raises special concern because it accumulates in and can damage the kidneys, the same organs that can be damaged by excessive protein consumption. And it can take 20 years for the body to eliminate even half the cadmium absorbed today.

Consumer Reports notes there are better, cheaper ways to bulk up. Case in point:A sandwich with 3 ounces of chicken and an 8-ounce glass of whole milk provides about 40 grams of protein, which is more than half the 72 grams needed by a 180-pound person and most of the 48 grams required by a 120-pound person.

By the editors of Consumer Reports at www.consumerreports.org .