Foods and ingredients originating from the ocean have continued to gain momentum in health-promoting circles.  Whereas fatty fish used to get all the attention, the spotlight then turned to seaweeds, and is now highlighting the little guys:  spirulina and chlorella, for example, are well represented on supplement shelves, and now phytoplankton is joining the game.

Companies that make and sell phytoplankton supplements talk a big game.  They claim that antioxidants and anti-inflammatory compounds in phytoplankton help with cardiovascular health, sleep, healthy skin, brain health, vision, liver, blood sugar, and energy, among others.

Some websites that offer prolific health advice also tout the wonders of phytoplankton supplements, including some of the benefits above as well as helping to reduce cancer risk, improve mood, regenerate cells, and detoxify the body (1)   They offer exciting claims about the benefits of supplementing with phytoplankton, but they provide little support for these claims.  Let’s look into those assertions more thoroughly here.

What Is Phytoplankton?

Phytoplankton, a category of microalgae (2) comprise more than 5,000  species.(3)  These single-celled, microscopic plants grow in lakes as well as oceans, and are the basis of many food ecosystems, with marine life from whales to jellyfish to snails relying on them as a food source. (4)

You may have heard of phytoplankton as a health hazard, actually, with beaches globally succumbing to “harmful algal blooms” (HABs) when phytoplankton grows too profusely making the water unsafe for human recreation.  The most commonly known phytoplankton-caused HAB is a “red tide.”  With this in mind, let’s look at why – in moderate doses, obviously – phytoplankton might be good for you.

Phytoplankton Nutrition

Many marine plants, including phytoplankton and marine algae more broadly, contain a vast array of nutrients, which vary from species to species. (5, 6)

What is difficult, and where much research is currently focused, is in determining which nutrients are abundant in which species, how to optimize those nutrients through altering growing conditions, (5) and how to isolate specific nutrients from specific phytoplankton species for use as supplements and functional-food ingredients. (6, 8) Wide-scale production of omega-3 fatty acids and beta-carotene from “algal biotechnologies” (using algae to make nutrients), is already solidly established.(5)

Omega 3s are actually a main factor in what sets phytoplankton apart.  Compared to two other increasingly popular marine supplements, chlorella and spirulina, phytoplankton are good sources of polyunsaturated fatty acids (PUFAs, a category which contains omega 3s), especially eicosopentanoic acid (EPA) and docosahexonoic acid (DHA), two essential omega 3s. (9)

In fact, a prime reason that many fish are such good sources of omega-3 fatty acids is that they feed on phytoplankton or other species that do.  Humans must eat foods with these essential fatty acids, since our bodies do not produce enough of them.  Most people currently do not get enough omega 3s in their diets, (7)which fuels interest in supplements containing them.  Phytoplankton could be a way to get more omega 3s at a lower cost.

In addition to beta-carotene and omega 3s, phytoplankton contain many more nutrients of interest, including additional carotenoids, vitamin E, other antioxidants, various amino acids (and linked amino acids called peptides), protein, phytosterols, iron and other minerals, and other classes of beneficial compounds including phytochemicals and phenolic compounds. (3, 6, 8)

Is There Any Research?

There is a lot of research on phytoplankton, though the vast majority of research is from the marine biology realm.  Most research that discusses phytoplankton and human health implications describes its potentially negative environmental repercussions that would affect human health, while extremely little exists on its potential beneficial impact.

Does Phytoplankton Improve The Immune System?

As a group, bioactive marine peptides have been reported to have immune-modulating and immune-stimulating properties. (2) Research that describe these properties, however, do not attribute them to phytoplankton specifically, and if they do, they attribute immune benefits to one or two of many thousands of types of phytoplankton, making it irresponsible to say broadly that phytoplankton improves immunity.(2)

The reported anti-inflammatory properties of phytoplankton (8) can help protect the antioxidant defense system of the body(10)which improves immunity by aiding health overall.  The array of beneficial compounds in marine bioactives (biologically active compounds) include vitamins, minerals, omega-3 fatty acids, and peptides, and are purported to help protect the body from a variety of short-term and chronic diseases. (10, 11)

One compound specifically, laminarum, discussed below as a carbohydrate source for phytoplankton, has been shown to have immune-enhancing effects.(12)

Still, no trials were found that used phytoplankton supplements to measure immune markers in humans or other animals, so impact in this area is purely speculative.

Bottom Line

More research is needed before we can say definitively that phytoplankton improves immunity.

Does It Help Prevent Cancer?

As described above, several journal articles also discuss the anticancer and anti-proliferative potential of marine bioactives due to the array of nutrients they contain,(2, 10, 11)  and some researchers attribute anti-cancer activity specifically to some of the carotenoids available in phytoplankton.(8)

In addition, imbalance of omega-6 to omega-3 consumption(7) – as in too much omega 6 and too little omega 3 – has been correlated with a greater risk of cancer,(13) which supports the idea that using phytoplankton supplements to increase dietary omega 3s might decrease cancer risk.

No studies were found that used phytoplankton supplements to gauge their effect on human health outcomes.  One study, however, did test several phytoplankton compounds against cancer cells in vitro (in a lab setting on cultured cells), and found that phytoplankton carotenoids, as well as specific amino acids and phenolic compounds, were responsible for killing the tumor cells, with the carotenoids being most associated with anti-proliferative activity.(3)

In another lab study, the compound laminarum, which phytoplankton use as a carbohydrate reserve, was shown to kill colon-cancer cells.  Researchers revealed a dose-dependent relationship, meaning that higher levels of laminarum killed more colon-cancer cells.(12) It is unknown how much laminarum is available in phytochemical supplements or how digestible it is.

Phytoplankton can also absorb carcinogens and other unhealthful pollutants(14) however, which is a concern when considering using it as a supplement.

Bottom Line

Initial research shows promise of certain phytoplankton compounds having an anti-cancer effect.  More research is needed.

Does It Have Detoxifying Properties?

Nearly all research that emerges from databases when searching for the relationship between phytoplankton and detoxification processes refers to how phytoplankton detoxify themselves or the water around them.  They often do this through binding with metallic minerals(15) (iron, for example) that may be advantageous to them but pose a risk to the overall health of the ocean in too-great concentrations.

Detoxification is a concept that is discussed very differently in the science world and the lay world.  In lay circles, discussions of detoxification often center around ridding the body of excess heavy metals, like mercury.

Phytoplankton does bind with metal minerals, which is why it is discussed as a good source of many of the minerals our bodies use.  We should be wary then whether the phytoplankton used as in supplements contains only metal minerals that are beneficial to our bodies.

Other considerations for how phytoplankton may help rid the body of unhealthful compounds are its antioxidants that can neutralize free radicals and fiber that helps sweep waste from the body.

Bottom Line

No research was found that specifically discussed phytoplankton and detoxification of the human body, so we can’t offer support of this benefit here.

Does It Help Cellular Regeneration?

Cellular regeneration is the process through which the body repairs and replaces cells.

Since marine bioactives as a group are known to contain numerous and varied antioxidants, (8, 10, 11) it could be assumed that they would help prevent damage from reactive oxidant species (“radicals” or “free radicals”).  This would protect cells that were threatened by free radicals or “oxidative stress.”

Otherwise, having a broad nutrient profile as phytoplankton is reported to have can also be an asset to keeping cells healthy.  However, no research was found discussing the specific potential of phytoplankton to regenerate human cells.

Bottom Line

No research equals no recommendation here, other than “use caution when using phytoplankton for unproven benefits.”

Does It Help The Heart?

Some phytoplankton produce phytosterols which have been shown to decrease serum cholesterol in humans when eaten.(9)  One species of phytoplankton, Schizochytrium sp, has even been authorized by the FDA for use as a food due to its high DHA and phytosterol content.(2)

Many species of phytoplankton are high in omega-3 fatty acids, including DHA and EPA.(2, 7) There is substantiated evidence that DHA improves heart and overall cardiovascular heatlh.(16) And, as with cancer, an imbalance of too much omega 6 and too little omega 3 has been associated with higher cardiovascular risk(13)

Thus, due to their omega-3 and phytosterol content, phytoplankton(2) as well as marine bioactives as a broader category(10, 11) are suggested to have anticoagulant and cholesterol-lowering properties, and are thus hoped to reduce cardiovascular diseases.

However, no research was found that looked at the use of phytoplankton in relation to heart health.

Bottom Line

Phytoplankton is a good source of omega 3s, and omega 3s are known to have numerous health benefits to humans, including cardiovascular health.  If you find a phytoplankton source that seems safe and responsible, you might reasonably consider it to be healthful.  Consult your physician with the product label in hand, as some normally beneficial compounds are not good for all health conditions.

Does It Improve Mood?

As with heart health, omega 3s have been frequently shown to support brain development and brain health, (16) and have helped alleviate depression. (9)  In addition, an abundance of omega 6 in relation to omega 3 may have neurodegenerative implications, meaning an effect detrimental to the brain, (13) which again suggests a need for greater dietary intake of omega 3s by humans.

Again, the omega-3 fatty acids, and specifically DHA and EPA, in phytoplankton and the greater marine bioactives category(2, 10) suggest that phytoplankton or other marine supplements might have a similar effect on mood issues as other sources of omega-3s.

Another online blog cited a pilot study that found promising results in this area.  This report has questionable legtimacy and is included only because less than a handful of reports using pytoplankton on humans, animals or cells are available.

Researchers randomized 41 young adults and gave them either a placebo, a supplement containing “CMP” (concentrated marine phytoplankton), or nothing (the control group).(17)  The group taking the CMP reported greater levels of happiness after taking the supplement.  However, numerous searches did not find peer review of this study, and after a decade the results have not been replicated.  The study was only presented very briefly, without full methods, results, and bibliography, and with no conflict-of-interest statement.

Bottom Line

More research is needed before phytoplankton can be recommended as a mood enhancer or protector, though, as with heart health, we do know that omega 3s are beneficial to the brain and that phytoplankton has omega 3s.

Is Eating Phytoplankton Safe?

While we sincerely hope that any supplement touting its benefits to human health could be considered safe, there is no regulatory system in place to assure this.

There are definite concerns about phytoplankton supplements.  First, although laboratory studies have shown good digestion of marine peptides in vitro (basically, in test tubes) when applying enzymes that would be available in the human digestive tract.(2) it is unknown how well humans digest and assimilate different phytoplankton species.(18)

And, as mentioned above, different phytoplankton species offer differ nutrient compositions, so more research is needed to find the best blend of species to use for the hoped-for benefits.(16)  Most supplements likely use multiple species combined for a better nutrient profile.

In addition, microalgae including phytoplankton are known to absorb pollutants, some of which are carcinogens to humans, (14)and therefore growing and harvesting conditions are extremely important.  Phytoplankton grown for use in supplements are likely grown in safe and isolated conditions, though, this is not always easily confirmed, and is not regulated.


Due to their desirable nutrient profiles, we will likely continue to see an increase in the use of phytoplankton and other marine plants for health supplements and as functional-food ingredients.  One concern, however, is the increasing temperature of ocean water.(13)

Warmer oceans inhibit the growth of phytoplankton, which are the primary producers of omega 3s, which in turn are a requirement for human life.(13)  Some researchers even speculate that a main detriment to human life of rising global temperatures will be the increasing prevalence of chronic health conditions as the availability – and thus our intake – of omega 3s declines.

One article sums up this phytoplankton discussion up well: “There is substantial evidence for the health benefits of algal-derived food products, but there remain considerable challenges in quantifying these benefits, as well as possible adverse effects.”(18)

If you see phytoplankton in the ingredients list on your functional foods, it should be safe since foods are more regulated.  If you’re considering supplemental phytoplankton, you might want to consider something that has more research behind it for the benefit you seek.  Bring on the green feeds, but bring on the research!