IngredientsNannochloropsis is a genus of unicellular and non-motile marine microalgae classified within the phylum Heterokontophyta, the class Eustigmatophyceae, and the family Eustigmataceae. The genus was initially defined by Hibberd and comprises six well-documented species: Nannochloropsis gaditana, Nannochloropsis granulata, N. oceanica, Nannochloropsis oculata, Nannochloropsis salina, and Nannochloropsis australis.
Taxonomic revision has added complexity to naming within this group. According to the World Register of Marine Species, N. gaditana (described by L.M. Lubián in 1982) is now accepted under the synonym Microchloropsis gaditana, and N. salina is similarly accepted as Microchloropsis salina, following a 2015 reclassification by Fawley, Jameson, and Fawley. Despite this nomenclatural update, the older names N. gaditana and N. salina remain ubiquitous in the primary and commercial literature and are used interchangeably in practice.
Nannochloropsis is characterized by small, unicellular, non-motile, and spherical or ovoid cells, typically ranging from 2 to 8 μm in size. The cells contain a yellow-green chloroplast with the main pigments being chlorophyll a and the xanthophylls violaxanthin and vaucheriaxanthin. Sexual reproduction has never been observed, and the genus appears to lack the genes for meiosis.
N. oculata is a eukaryotic alga that is unicellular with polysaccharide cell walls and coccoid cells. Nannochloropsis contains a yellow-green chloroplast, which contains chlorophyll a, zeaxanthin, and beta-carotene, and specifically lacks chlorophyll b and c.
In Nannochloropsis sp., cellulose is the main component of its tough and highly recalcitrant cell wall. This distinctive, multi-layered cell wall is a defining structural feature that has significant implications for nutrient bioavailability and digestibility (discussed in Section 6).
Nannochloropsis occurs in both freshwater and marine environments. The genus contains five to six species, of which only N. limnetica occurs in freshwater, with few differentiating features. The algae is described as a phototrophic unicellular, non-zoospore producing, free-floating alga having a diameter of 2–4 μm, growing in a temperature range of 11–16°C.
According to the Food and Drug Administration, microalgae are classified into two main categories — no toxin known and generally recognized as safe — and under these categories fall many unique algae such as Arthrospira platensis, Chlorella vulgaris, Nannochloropsis sp., Dunaliella salina, and Haematococcus pluvialis, most of which are available in the markets as dietary supplements in the form of tablets, capsules, and powder.
For human dietary use, Nannochloropsis is commercially available in several forms:
Large-scale cultivation of Nannochloropsis in open raceway ponds and sealed tubes has proven to be feasible. For human supplement-grade production, closed photobioreactors are typically preferred to minimize contamination risk and allow better environmental control.
Nannochloropsis has no documented history of traditional use in the ethnobotanical or ethnopharmacological sense — that is, it was not intentionally consumed by any recorded human culture prior to the modern era of algal science. Unlike macroalgae (seaweeds) with deep culinary traditions in Asia, this microscopic alga exists at the nanometer-to-micrometer scale and was not isolated or identified until the late twentieth century.
One of the earliest documented uses of Nannochloropsis was in aquaculture, particularly as a feedstock for fish larvae, shrimp, and shellfish, due to its high EPA content which significantly improves the health and growth rates of farmed marine species. Nannochloropsis oculata is among the species produced specifically for rotifer and Artemia feeding in fish hatchery systems. This aquacultural application, well-established from at least the late 1980s and 1990s, established the foundation of understanding regarding the alga's nutritional profile and safety characteristics before its transition to human supplement use.
Nannochloropsis sp. has been utilized as a food source in aquaculture, providing a source of omega-3 fatty acids, and more recently a N. oculata-derived oil has been determined safe for use in dietary supplements. The genus's entry into human nutrition is thus a contemporary development, driven by biotechnological research rather than any traditional medicinal or culinary practice.
There is great interest in Nannochloropsis production mainly because this microalga contains a considerable amount of lipids, with lipid content ranging on average from 25–45% of dry weight.
The species synthesizes fatty acids in a number of different classes: neutral lipids comprised of free fatty acids, triglycerides, and diglycerides, and polar lipids comprised of phospholipids and glycolipids. Over two-thirds of the fatty acids produced by Nannochloropsis consist of eicosapentaenoic acid (EPA = C20:5ω3), palmitic acid (C16:0), and palmitoleic acid (C16:1 = C16:1ω7). The species produces only one other omega-3, alpha-linolenic acid (ALA = C18:3ω3). Docosahexaenoic acid (DHA = C22:6ω3) is not produced by the species at all.
Nannochloropsis sp. is one of the potential candidates with EPA content of up to 30% of total fatty acids, and a considerably high amount of essential bioactives like carotenoids and vitamin D.
In N. gaditana, the major fatty acids — palmitic, palmitoleic, and EPA — were detected in ranges of 18.3–23.0%, 22.9–26.1%, and 29.3–33.8% respectively. Nannochloropsis gaditana lipid extracts were characterized by a high percentage of PUFA (39.7–47.0%) and a low n-6/n-3 ratio of 0.3, showing excellent nutritional properties.
A distinguishing feature of Nannochloropsis-derived EPA is the molecular form in which it is found. The extract contains polar lipids (15%) rich in galactolipids and phospholipids, which provides nutritional characteristics different from other forms of long-chain n-3 PUFAs. This unique polar lipid composition confers surfactant properties that trigger the formation of micelles in the stomach, and those spontaneous emulsions facilitate the digestion and delivery of LC n-3 PUFA while minimizing fishy burps and aftertaste.
The major carotenoid produced by Nannochloropsis is violaxanthin, which exhibits anti-inflammatory, anti-photoaging, and antiproliferative activities. The cells additionally contain chlorophyll a as a primary photosynthetic pigment.
Pigment and metabolite analyses of Nannochloropsis extracts reveal that they contain various carotenoids and polyunsaturated fatty acids alongside significant quantities of phenolic and flavonoid compounds, which are known to have anti-inflammatory activities.
The alga contains PUFAs (including EPA), carotenoids (astaxanthin, canthaxanthin, β-carotene, zeaxanthin, violaxanthin), and phenolic compounds.
Violaxanthin has been reported to exhibit anti-inflammatory activity in macrophage cells along with antiproliferative activity against human cancer cell lines. Furthermore, violaxanthin has appeared as an excellent radical scavenger with strong antioxidative capacity, thereby inhibiting hemolysis induced by H₂O₂ and lipid peroxidation. Recent studies have also demonstrated the protective effect of violaxanthin against ultraviolet-B-induced skin damage.
Nannochloropsis species contain 28.7–40.4% carbohydrates, 22.2–37.4% crude protein, and 15.1–21.7% total lipids on dry weight basis, as well as minerals, vitamins, and antioxidants such as carotenoids. Nannochloropsis oceanica specifically has been reported to contain 35–44% protein by dry weight.
The N. oceanica biomass shows high protein content including essential amino acids, together with high PUFA content, predominantly EPA, as well as vitamins and carotenoids. The microalga also provides substantial amounts of vitamins including B12, E, and folate, alongside minerals such as iron, magnesium, and zinc.
Minor constituents of the algal oil include phytosterols and palmitoleic acid, which may contribute to observed lipid homeostasis effects.
Recent metabolomic analyses have identified over 200 bioactive compounds, including chlorophyll derivatives, tocopherols, and phenolic compounds with demonstrated antioxidant properties.
The genus Nannochloropsis is particularly distinguished by its high levels of eicosapentaenoic acid (EPA), violaxanthin, and other xanthophylls, which exhibit immunomodulatory effects. These metabolites have been shown to decrease the production of nitric oxide (NO) and prostaglandin E2 (PGE2), to inhibit proinflammatory cytokines, and to influence pathways related to nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB).
The polar lipid form (glycolipids and phospholipids) to which EPA is conjugated in Nannochloropsis extracts may partially explain greater reductions observed for triglycerides. Polar lipids extracted from plant sources have been shown to decrease both triglycerides and total cholesterol independently from their fatty acid profile, suggesting that the polar lipid fraction may also contribute to the observed lipid-lowering effect.
Some large-scale pharmaceutical trials specifically investigating EPA-only treatments (JELIS, REDUCE-IT, RESPECT-EPA) demonstrated superior outcomes compared to trials using combined DHA and EPA treatments (VITAL, ASCEND, STRENGTH, OMEMI). This finding has ignited significant debate regarding the distinct roles of each LC n-3 PUFA in cardiovascular protection, with EPA apparently emerging as a prominent player.
The antioxidant compounds in Nannochloropsis mainly act to neutralize reactive oxygen species (ROS) through hydrogen atom transfer, though other mechanisms have been described, such as inactivation of radicals by monoelectronic transfer and chelation of transition metals involved in the Fenton reaction, thereby preventing the formation of highly reactive hydroxyl radicals.
EPA in Nannochloropsis oceanica has been found in cell studies to effectively promote antioxidant activity to counter amyloid-beta-induced oxidative stress in neural cells.
The inclusion of N. gaditana in animal diets led to higher protein and total mineral intake as well as higher fecal weight. Regarding digestive utilization of protein, significantly higher net nitrogen absorption in microalgae-supplemented diets was ascribed to the higher amount of protein provided by the diet. Moreover, significant increases in nitrogen digestibility after cell wall treatment were associated with cell wall disruption.
Changes in microbiota composition, together with increased activity of antioxidant compounds in the potentially non-absorbable fraction, may contribute significantly to the protection of the colon. Dietary administration of the microalgae also led to hypertrophy of the cecum, which can be a result of the fermentation process of non-digestible components. These beneficial aspects at the digestive and metabolic level point to treated N. gaditana as a valuable protein supplement with an associated prebiotic action.
Lipid-lowering effects represent the most clinically studied application of Nannochloropsis in humans.
Key RCT (2020): A double-blind, randomized, placebo-controlled trial investigated AlmegaPL®, a polar-rich oil (>15%) derived from the microalga Nannochloropsis containing EPA (>25%) with no DHA. Participants (n = 120) were given a capsule of 1 g/day of either AlmegaPL® or placebo for 12 weeks. Differences in the Omega-3 Index, cardiometabolic markers, and other general health indicators were measured at baseline, six, and twelve weeks. Previous findings from this randomized controlled clinical trial demonstrated the ability of AlmegaPL® supplementation to reduce cholesterol levels.
Post-market cohort study (2024): Building upon those RCT findings, a post-market cohort study targeted actual end-users of the supplement. Participants were recruited from a new subscriber database of AlmegaPL® capsules (1000–1100 mg/day). Changes in circulating triglycerides (TG), remnant cholesterol (RC), LDL, HDL, total cholesterol (TC), high-sensitivity C-reactive protein (hs-CRP), glucose, and glycated hemoglobin (HbA1c) were monitored at baseline, Month 3, and Month 6 of supplementation. The study flow included 223 participants who completed the study in the per-protocol population, and 292 participants in the intention-to-treat population. Collectively, these findings highlight AlmegaPL® as a natural over-the-counter option for EPA-only polar lipid that appears particularly effective in maintaining blood lipid levels in a generally healthy, normolipidemic population.
Evidence characterization: Additional in vitro and animal studies have also shown that Nannochloropsis oil can reduce triglyceride accumulation and improve lipid metabolism. However, the number of high-quality human trials remains limited, and most studies use relatively modest doses over short durations. The triglyceride-lowering effect appears comparable, though generally less pronounced, than that observed with higher-dose fish oil supplements. Several of the industry-funded trials used proprietary AlmegaPL® preparations, and the primary funder of key human studies (Qualitas Health Inc.) had a financial interest in outcomes, which should be noted when interpreting results. The authors of the 2024 cohort paper declared that some authors were employees of Qualitas Health Inc., and the study received funding from Qualitas Health Inc.
Unique positioning as EPA-only source: Nannochloropsis produces exclusively EPA, unlike all other natural sources of LC n-3 PUFA (e.g., fish, krill). Plant-based AlmegaPL® derived from Nannochloropsis is the first photosynthetic source of LC n-3 PUFA available for human consumption in the USA.
Kagan et al. demonstrated that LC n-3 PUFAs in AlmegaPL® were more bioavailable than other forms of LC n-3 PUFA. This enhanced bioavailability is attributed to the polar lipid carrier matrix. The study demonstrating this was performed in healthy young males using Nannochloropsis oculata and krill oil comparators. This result has not yet been replicated in large-scale independent trials.
In a rat study, animals received a control or high-fructose, high-sucrose, high-saturated-fat diet for eight weeks and then received 5% freeze-dried N. oceanica in these diets for the final eight weeks. Rats on the unhealthy diet developed obesity, hypertension, dyslipidemia, fatty liver disease, and left ventricular fibrosis. N. oceanica supplementation increased lean mass in both the control and high-diet groups, possibly due to increased protein intake, and decreased fat mass in high-diet rats. However, intervention with N. oceanica did not change cardiovascular, liver, and metabolic parameters or gut structure. The relative abundance of Oxyphotobacteria in the gut microbiota was increased. N. oceanica may be an effective functional food against metabolic syndrome as a sustainable protein source.
Evidence characterization: This is a preclinical animal study. Results regarding fat mass reduction and gut microbiota modulation are promising but cannot be directly extrapolated to humans without clinical replication.
Functional extracts from treated N. gaditana exhibited higher antioxidant activity than untreated controls. Furthermore, the treated microalga induced hypoglycemic action, higher nitrogen digestibility, and increased hepatic antioxidant activity. In conclusion, N. gaditana has interesting hepatoprotective, antioxidant, and anti-inflammatory potential, proving itself an ideal functional food candidate, especially if the microalga is treated to increase the fragility of its cell wall before consumption.
EPA from N. gaditana has been found in animal studies to lower blood glucose levels, enhance nitrogen digestibility, and increase liver antioxidant activity. It has also shown positive effects on lipid metabolism disorders in mice and effectively reduced the incidence of fatty liver disease caused by a diet rich in saturated fatty acids.
Evidence characterization: These antioxidant and anti-inflammatory findings are based predominantly on in vitro (cell culture) and animal models. No adequately powered human randomized controlled trials have directly tested Nannochloropsis extracts for anti-inflammatory outcomes in humans as of the available literature.
Amyloid-beta protein is a key factor in the pathogenesis of Alzheimer's disease. Oxidative stress is involved in the biochemical pathway by which amyloid-beta can lead to neuronal dysfunction. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have been reported to protect against Alzheimer's disease. In one in vitro study, researchers utilized N. oceanica to produce omega-3 fatty acid. When urea levels (nitrogen source) were lowered from 2 to 0.2 g/L in cultures, EPA production increased. EPA in N. oceanica effectively promoted antioxidant activity to counter amyloid-beta-induced oxidative stress in Neuro-2A cells. These results indicate that N. oceanica may be potentially used as a therapeutic agent or as a functional food that promotes protection against neurodegenerative disease.
Evidence characterization: This is cell-culture (in vitro) evidence only. No human or animal trials specifically examining Nannochloropsis for neurodegenerative disease outcomes have been identified.
Extracts of Nannochloropsis sp. containing PUFAs (including EPA), carotenoids, and phenolic compounds have shown a wide range of skin protective functions with low cytotoxicity in cell studies, including antioxidant, anti-melanogenic, anti-inflammatory, UV protective, anti-wrinkling, and skin moisturizing activities. Lipid extracts from Nannochloropsis oceanica have been found to show preventive effects on metabolic changes in epidermal cells induced by UVB radiation.
Evidence characterization: Skin-related findings are based on in vitro cell studies. No published human clinical trials examining topical or oral Nannochloropsis use for skin endpoints have been identified.
Animal evidence suggests that treated N. gaditana functions as a valuable protein supplement with an associated prebiotic action. However, digestibility and bioavailability are major concerns in the case of Nannochloropsis. The robust and recalcitrant cell wall limits the efficiency with which the body can access intracellular nutrients without prior processing (e.g., mechanical disruption, enzymatic treatment, or high-pressure homogenization).
The following dosages are drawn exclusively from published research and are reported descriptively:
Human clinical dosages for whole-cell Nannochloropsis biomass have not been well standardized in the peer-reviewed literature outside of lipid extract formats. The EPA content and dosage are the primary parameters that have been controlled and measured in clinical trials.
Despite being beneficial as food and feed, only a few microalgal species are approved as GRAS by the FDA. Microalgal species approved as GRAS include Arthrospira maxima, Arthrospira platensis, Chlamydomonas reinhardtii, Chlorella protothecoides, Dunaliella bardawil, Haematococcus pluvialis, Prototheca moriformis, Schizochytrium sp., and Ulkenia sp. As of available records, Nannochloropsis itself does not appear on the U.S. FDA's public GRAS list. It has, however, received New Dietary Ingredient (NDI) notification status and has been subject to formal toxicological evaluation for novel food use.
A comprehensive toxicological evaluation of N. gaditana oil as a new food ingredient included an acute oral toxicity study, genotoxicity studies, teratogenicity study, and subchronic toxicity study. In the acute oral toxicity study, the LD50 was >8.4 g/kg body weight. In genotoxicity studies (mammalian erythrocyte micronucleus, chromosomal aberrations, and Ames test), all dose groups showed no significant changes compared to negative controls. A teratogenicity study demonstrated no adverse effects on maternal body weight, reproductive capacity, or fetal development in rats, with a no-observed-adverse-effect level (NOAEL) of 2.8 g/kg body weight. Similarly, the 90-day subchronic toxicity study identified a NOAEL of 2.8 g/kg body weight, as no treatment-related abnormalities were observed in body weight, hematology, blood biochemistry, urinalysis, or histopathology.
A 14-day repeated-dose toxicity study in male and female Sprague-Dawley rats administered 0 or 10 mL/kg body weight/rat N. oculata (10E8 viable cells/mL) suspension by oral gavage once daily found no mortalities and no signs of toxicity. No treatment-related effects were seen for body weight, food consumption, urinalysis, clinical chemistry, hematology, gross pathology, organ weights, or histopathology. The N. oculata suspension was concluded to have no toxicity in rats, confirming the algal strain is not pathogenic when administered orally.
No toxins produced by Nannochloropsis are known, and the toxicological safety of this microalga has been supported by its long-term use as food for marine fish and shellfish larvae. Kafaie, Loh, and Mohtarrudin confirmed the absence of toxicity of N. oculata by performing an acute intoxication test (12 g/kg body weight) and a 60-day sub-chronic test (6 g/kg/day) on Sprague-Dawley rats. No abnormalities or negative metabolic effects were observed, except for a significant reduction in blood creatinine that was deemed of no toxicological significance.
Nannochloropsis is widely exploited in the aquaculture sector due to its rich fatty acid composition. However, digestibility and bioavailability are major concerns in the case of Nannochloropsis. Pre-treatment of the Nannochloropsis biomass improves digestibility. Methods including high-pressure homogenization, enzymatic treatment, sonication, and freeze-drying are used in manufacturing to disrupt the tough cell wall and increase the release of intracellular contents.
Microalgal cells can adsorb metals, thereby altering metal bioavailability. Metals are adsorbed either to the cell surface or taken up into the cell. Depending on the concentration of each metal in solution, M. gaditana accumulates up to 6.8 pg cell⁻¹ copper and 1.5 pg cell⁻¹ lead. This property means that the environmental quality of cultivation water significantly impacts the safety profile of the final biomass. Supplement-grade products should be tested and certified to meet regulatory thresholds for heavy metals including lead, cadmium, arsenic, and mercury.
Because Nannochloropsis-derived EPA shares the pharmacodynamic profile of fish oil-derived EPA, relevant interactions include:
Human clinical trial participants receiving AlmegaPL® at 1 g/day for up to 6 months generally tolerated the supplement well; no serious adverse events attributable to the supplement were reported across the available published studies. The polar lipid carrier matrix was noted to reduce the fishy aftertaste often associated with marine-derived omega-3 products. Individuals with documented algae or seafood allergies should exercise appropriate caution, though the allergenicity of Nannochloropsis specifically has not been formally characterized in human subjects.
The body of evidence for Nannochloropsis as a human dietary supplement is early-stage but growing. The most robust area is EPA-mediated lipid profile modulation, supported by at least one published randomized, double-blind, placebo-controlled trial and one real-world cohort study, albeit with industry funding and relatively small sample sizes. All other putative health benefits — including anti-inflammatory, neuroprotective, hepatoprotective, dermatological, and gut microbiota effects — remain at the preclinical (in vitro and/or animal) stage. Independent, large-scale human trials across these domains are needed to confirm clinical relevance, optimal dosing, and long-term safety.
Health conditions that Nannochloropsis may help support.
Body systems that Nannochloropsis may help support.
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