Spirulina is a living plant alga and therefore its nutritional makeup will reflect the environment in which it was grown. If the Spirulina grows in clean, fresh water, the Spirulina will have an exceptional nutritional profile. If the Spirulina grows in water contaminated with heavy metals and toxins, the Spirulina is likely to contain these heavy metals and toxins as well.
Watch an excellent video about Organic Spirulina Supplements –
For this reason, never eat or take Spirulina that you find growing locally in a pond or lake. It could be contaminated with toxins or bacteria. If you choose to purchase a Spirulina supplement, make sure you are buying from a reputable company. You have to right to ask where the Spirulina was grown. You have the right to ask if the Spirulina has been tested for heavy metals and toxins. If the company cannot provide you with this information, do not buy the product.
Spirulina may cause occasional gastrointestinal side effects. These side effects include nausea and diarrhea. Side effects are rare and usually decrease as you build up a tolerance to Spirulina.
Ask a doctor before starting any supplement program, especially if you are pregnant or nursing.