Are plant-based calcium supplements, like AlgaeCal, better than regular calcium supplements?

Answer:

AlgaeCal (Basic) contains calcium, magnesium and trace minerals derived from algae with added vitamin D. AlgaeCal Plus also includes added vitamins C and K, boron, and additional magnesium. Testing by ConsumerLab.com in 2011 found AlgaeCal Plus to contain a higher amount of lead (a toxic heavy metal) (5.2 mcg per daily serving of 4 capsules) than many other calcium-containing supplements. Testing in 2017 found less lead, although still higher than acceptable to CL, but also less magnesium than listed on the label.

Studies sponsored by the makers of AlgaeCal found that it increased bone mineral density in healthy men and women, although there were weaknesses to the study design. There do not appear to be any clinical studies comparing the effects of AlgaeCal to other forms of calcium, such as calcium carbonate or calcium citrate nor to other calcium + vitamin D supplements. For more about this, plus evidence for other forms of calcium, see the Calcium Supplements Review >>

Updates:
CL members have contacted AlgaeCal about CL's findings of lead in its AlgaeCal product and have shared the responses they received with us. These are posted below along with our comments:

(11/17/15): We were recently informed by a CL member that AlgaeCal provided the following information in response to the member's inquiry about lead in AlgaeCal Plus. In its response, AlgaeCal appears to acknowledge the amount of lead found by ConsumerLab.com in 2011, but provides information which we consider misleading regarding how that amount of lead compares to what is found in the U.S. diet by stating:

"There are 5.2 mcg of lead in a daily dosage of 4 capsules of AlgaeCal Plus. It is just like taking a daily serving of other typical plant foods according to the FDA's publication, Total Diet Study Statistics on Elements Results (December 11, 2007): Food Amount of Lead in a 4 Ounce Serving Mixed nuts, roasted 10.2 mcg Brussels sprouts, fresh, boiled 7.9 mcg Sweet potato, fresh, baked 7.2 mcg Spinach, boiled 7.0 mcg Avocado, raw 4.5 mcg. Furthermore, the US Government's Centers For Disease Control publication 'Inorganic Lead Exposure, Metabolism and Intoxication' states that 'typical intakes of lead from food, beverages and inhaled air are in the order of 300 to 500 mcg per day.' "

The most recent Total Diet Study (FDA 2014) shows much lower amounts of lead in foods than AlgaeCal states above. The FDA found no detectable lead in peanuts or Brussels sprouts and, based 3 oz servings, only 1.1 mcg in sweet potatoes (0.013 mcg/gram or mg/kg), 0.3 mcg in spinach (0.004 mcg/g) and 0.085 mcg in avocado (0.001 mcg/g). We could not find the CDC publication referenced by AlgaeCal, but found another CDC publication (ATSDR Public Health Statement for Lead 2007) which states that, based on recent studies, "the average dietary intake of lead was about 1 microgram (a microgram is a millionth of a gram) per kilogram of body weight per day." For an adult weighing 70 kg (154 lbs), this would be 70 mcg -- nowhere near the 300 to 500 mcg stated above. In short, the amount of lead in AlgaeCal Plus is higher than in most foods and calcium supplements and adds significantly to one's intake of lead. (Note: Be aware that in 2018, the FDA lowered the maximum intakes for lead from all sources from 70 mcg per day to 12.5 mcg per day in adults, and from 6 mcg per day to 3 mcg per day in children.)

(6/12/18): AlgaeCal recently provided the following information in response to a CL member's inquiry about lead in AlgaeCal Plus:

"Lead is omnipresent, albeit in very minute amounts, in our environment, and thus our food. There are 0.23 ppm (0.556 mcg) of lead in a daily dosage of 4 capsules of AlgaeCal Plus. There is no extraction process with the raw Algae product, it is merely live harvested from the protected beaches, dried and ground. This is one of the many trace minerals and is far below any problematic amounts — well within international safety standards. The vast majority of environmental lead present is safely excreted from the body every day, save for times of unusually high exposure. A study of lead levels in the USA food supply, found HERE, states that "Data obtained on the lead content of milk, eggs, meat, fish, and shellfish indicate that the mean levels in these unprocessed foods varied from 0.02 to about 0.4 ppm, with the lowest level in milk." To attempt to remove this lead would damage the trace mineral content that makes AlgaeCal so effective for bone health. According to THIS Health Canada informational page, "In adults with a normal diet, 3-15% of ingested lead is absorbed into the blood by the intestine. Less than 5% of absorbed lead stays in the body". So you can see that AlgaeCal is a safe, natural way to increase bone density."

The amount of lead that AlgaeCal now claims to be in its product (0.556 mcg per 4 capsules) would pose little risk. However, it is about half the amount that ConsumerLab.com found in its most recent tests in 2017 of AlgaeCal Plus.