Cindy:
Some of the levity in the responses to your question reflects the fact that this forum is oriented toward analytical issues. Your question involves biochemistry in general. That said:
Most proteins contains all 20 of the amino acids that are found in proteins. How useful a particular set of proteins is for nutritional purposes is determined by the ratio of the different amino acid it contains. There are 10 amino acids that our bodies can't make (8, if you take into account the fact that 2 of the 10 could be made from precursors in the set of eight). Those are called essential amino acids. The protein from meat, eggs and milk (hence your whey) contains pretty much the right ratios; these are called "whole proteins". While cereal grains can contain a significant amount of protein, they tend to be low in the essential amino acids lysine and methionine (hence the interest by Big Agriculture companies in developing high-lysine varieties of corn and high-methionine soybeans). You need to supplement those proteins with protein that does have more of the missing amino acids. This is usually done by combining foods: rice + beans; potatos + milk; soybeans + Brazil nuts; etc. Now, in order to assess the nutritional value of this Spirulina, check its amino acid ratio against what you'd find with meat, egg or milk protein. If it's a good match, then by all means use it as a protein source if you have qualms about eating a steak.
