Due to very high Vitamin K content, patients undergoing anticoagulant treatments should not change consumption patterns of spirulina without seeking medical advice to adjust the level of medication accordingly.
Like all protein-rich foods, spirulina contains the essential amino acid phenylalanine (2.6-4.1 g/100 g), which should be avoided by people who have phenylketonuria, a rare genetic disorder that prevents the body from metabolizing phenylalanine, which then builds up in the brain, causing damage.
Spirulina is rich in phycocyanin, an antioxidant which prevents blood clotting and strokes, according to an article published in the “Journal of Agricultural Food Chemistry.” Spirulina contains 15,000 to 19,000 mg of phycocyanins per 100 grams"
now I just read this....so i feel a little better again. maybe it is safe.
if Nasa has messed around with feeding astronauts nothing but algae, it must be somewhat safe and packed full of good stuff.