One tablespoon of dried spirulina contains 2 milligrams of iron. This is 25 percent of the 8 milligrams of iron men need each day and about 10 percent of the 18 milligrams women should have on a daily basis. Iron is a mineral present in your red blood cells, and it enables these cells to transport oxygen throughout your body. An iron deficiency can lead to fatigue and a depressed immune system. Not getting enough iron in your diet can lead to a deficiency, and adding spirulina to your diet is one way to increase your intake of this key mineral.
Spirulina contains iodine, a trace element that is naturally present in certain foods, especially foods that come from the ocean. Iodine plays an essential role in thyroid function, as well as the health of your skeleton and central nervous system. Your daily requirement of iodine is 150 micrograms, but the amount you get from spirulina varies. A serving of spirulina can contain from 16 micrograms, or about 10 percent of your daily need, up to over 15,000 micrograms, or over 1,000 percent of what you need each day. Too much iodine can cause a goiter and thyroid deficiencies, but an overdose is quite rare. The upper limit for iodine is 1,100 milligrams per day.
Though iron and iodine are the most abundant nutrients present in spirulina, it also contains small amounts of other vitamins and minerals as well. One tablespoon of dried spirulina contains 0.35 milligrams of vitamin E, a nutrient that helps prevent cell damage, which can reduce your risk of heart disease and certain types of cancer. The same serving of spirulina supplies small amounts of potassium for heart health, vitamin A for normal eyesight and folate, a nutrient that can help prevent birth defects.
Spirulina is available in pill, powder or flake forms. A typical dose of spirulina is equal to about 500 milligrams, but you shouldn’t use any amount of the product without speaking with your doctor first. Tell your doctor about any medications or supplements you take because certain ones might interact with spirulina. Only buy and use reputable brands of spirulina. Some spirulina can be contaminated with substances that are toxic. If you have an autoimmune disease or phenylketonuria, don’t use spirulina. If you’re pregnant or breastfeeding, ask your doctor if it’s safe for you to use spirulina.
Spirulina has 2300% more iron than spinach
Spirulina has 3900% more beta carotene than carrots
Spirulina has 300% more calcium than whole milk
Spirulina has 375% more protein than tofu
These statements make spirulina look like an ultra-concentrated superfood. And these statements may be true – technically. But these nutrition facts are “per calorie” and not “per serving”, and there’s a huge difference between the two.
Spirulina Hype vs. Spirulina Reality
For example, a “beginner dose” of spirulina powder is up to 1 teaspoon (3-5 grams, approx. 10 calories) per day while a “normal dose” is 1-2 teaspoons per day (6-10 grams). A “therapeutic dose” is generally considered a tablespoon (about 16 grams, approx. 20 calories). A 16 gram serving of spirulina does not contain 2300% more iron than a serving of spinach, nor does it contain 375% more protein per serving than tofu.
While spirulina typically contains about 60% protein, on average, you’d be be lucky to get maybe 2 grams of protein in a teaspoon and perhaps 6 in a tablespoon at most. As a protein source, however, spirulina is extremely expensive. There are much cheaper, whole food sources of protein that also provide adequate calories to be part of a meal, not just a dietary supplement.
Vitamin B12 Content of Spirulina
One way that the nutritional benefits of spirulina are dangerously over-hyped is in its B12 content. Surprisingly, most online marketers of spirulina still promote it as a rich source of vitamin B12 despite studies showing that the B12 found in spirulina (and all other plant sources) are an analogue form that is not metabolized by humans.
Not only will the analogue form of vitamin B12 found in spirulina NOT prevent vitamin B12 deficiency, it might actually facilitate deficiency since analogue B12 competes with bio-available B12 for absorption. In short, spirulina is not a B12 supplement and should never be relied on to provide this vitamin.
Other Nutrients in Spirulina
Spirulina is a good source of vitamin B2, copper and it contains some iron (up to 2mg per tablespoon). However, it is not a particularly rich source of any other essential vitamin or mineral, including calcium (less than 9mg in a tablespoon). When you look at the nutrition information of spirulina per serving, it doesn’t really stand out from other whole foods, and many whole foods simply have higher amounts of nutrients per serving than spirulina.
Nutrition labels on a variety of spirulina products may vary, and they tend to have “more nutrition” than what is listed in official food nutrient databases, such as the USDA National Nutrient Database for Standard Reference from which we get most of our nutrient information from. This alone makes me skeptical about the integrity of the nutrition value of many spirulina products, not to mention the erroneous claims about B12 content that manufactures and sellers often promote.
Dried and powdered spirulina as it is currently marketed and sold is not a whole food. While Aztecs may have consumed it as part of their diet prior to the 16th century, and it is still consumed in Central Africa, the dried spirulina cakes typically eaten are not the same thing as highly refined, powdered, pharmaceutical-grade supplements available for sale.
Studied Health Benefits of Spirulina
There have been a variety of animal studies and a handful of human clinical trials that suggest possible health benefits of consuming spirulina including a potential to reduce LDL to HDL cholesterol ratio and improve antioxidant status as well as help with hay fever.
Animal and in vitro studies showing potential benefits of spirulina cannot be claimed as health benefits without analyzing results obtained by conducting double blind, placebo controlled clinical studies on humans. There is no clinical evidence that spirulina will help with weight loss or detoxification.
The health benefits attributed to spirulina are not unique to this cyanobacteria. In fact, most plant-based whole foods contain compounds (in larger amounts per serving) that promote health, weight loss, detoxification and disease prevention.
I am not totally anti-spirulina, though. I mean, I won’t avoid it at a smoothie or juice bar. I do not feel that it is necessary to take it and most people will not experience any health benefit (besides placebo effect) from taking it.
If anything, spirulina is best at being profitable for those who sell it. I just cant justify the expense of this powdered, refined “superfood” when fresh, whole fruits and vegetables provide real food and better nutrition per serving.