Tetraselmis chuii (marine microalgae)

Also called T. chuii, TetraSOD, Oceanix, marine phytoplankton, SOD-rich microalgae.

Best grade C across 7 graded outcomes Other Last checked Oct 21, 2026

The short answer

From 9 sources

Tetraselmis chuii is a marine microalga sold as an SOD-rich ingredient at 25-250 mg a day. Small trials, most funded by or supplied by its maker, report better exercise recovery and aerobic capacity, and an 80-man trial found better semen quality in infertile men. Trials were short and independent replication is lacking.

Every graded outcome on this page

7 rows · line = participants

Grade CSemen quality and live births in men with idiopathic infertilityMale fertilityn 80
Grade DBody composition, hormones and blood countsBody compositionn 46
Grade DAerobic fitness and blood values in soccer playersEndurancen 32
Grade DStrength recovery and salivary IgA after hard resistance trainingExercise recoveryn 22
Grade DPerceived recovery and jump power during overreaching resistance trainingExercise recoveryn 22
Grade DMuscle damage and performance after a strenuous cross-training eventExercise recoveryn 18
Grade DPeak oxygen uptake and muscle antioxidant genesEndurancen 13
4 more graded outcomes, in the evidence chapter

Key facts

Male fertility: 250 mg/day for 3 months improved sperm concentration and motility and cut DNA fragmentation vs placebo in 80 infertile men¹
Endurance: 25 mg/day for 14 days raised VO2peak vs baseline in 13 men, with higher muscle antioxidant gene expression vs placebo²
Dose: Trials used very small amounts: 25-250 mg/day^1,2,3,5
Regulatory status: Authorized in the EU as a novel food in 2014 and as a food supplement in 2017⁶
Conflicts of interest: Every human trial cited here was funded by, co-authored by, or supplied by the companies that make or sell the ingredient^{1,2,3,4,5,8,9}

What it is

Tetraselmis chuii is a green marine microalga, rich in the antioxidant enzyme superoxide dismutase (SOD), sold as a low-dose powder ingredient.

How it works

Proposed

The ingredient is characterized by high superoxide dismutase activity. In a human crossover trial it raised muscle expression of NRF2 and related antioxidant enzyme genes, which may protect cells against oxidative stress; how an oral enzyme exerts these effects is not established.^2,6

Forms

Form

The form on this page
Form	Elemental %	Absorption (human data)	GI tolerance	Studied for
SOD-rich T. chuii powder (TetraSOD, Oceanix)	Varies^1,2,4Not applicable (whole compound or extract; no elemental fraction)	Not reported in the trial abstracts.^2,4	No side effects reported over 2-12 weeks at 25-250 mg/day.^2,4,9	Exercise performance and recovery, male fertility

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

7 graded outcomes, largest study first

All 7 graded outcomes found an improvement. The largest, a 2026 randomized trial of 80 people on semen quality and live births in men with idiopathic infertility, found an improvement.

By sizeTable

1Semen quality and live births in men with idiopathic infertility

Improved · Grade C · RCT, 80 people, 2026

Men with idiopathic infertility (Spain)

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Semen quality and live births in men with idiopathic infertility	Improved	80	Grade C · RCT, 2026	Men with idiopathic infertility (Spain)
Body composition, hormones and blood counts	Improved	46	Grade D · RCT, 2022	Healthy young men (Spain)
Aerobic fitness and blood values in soccer players	Improved	32	Grade D · Pilot RCT, 2020	Amateur male soccer players (Spain)
Perceived recovery and jump power during overreaching resistance training	Improved	22	Grade D · RCT, 2021	Regularly exercising men and women aged 18–45 (US)
Strength recovery and salivary IgA after hard resistance training	Improved	22	Grade D · RCT, 2021	Healthy men and women (US)
Muscle damage and performance after a strenuous cross-training event	Improved	18	Grade D · RCT, 2020	Endurance-trained adults running about 30 miles a week (US)
Peak oxygen uptake and muscle antioxidant genes	Improved	13	Grade D · Crossover RCT, 2025	Healthy young men (UK)

Every graded row

7 rows

Form tested

Showing 7 of 7 outcomes. Human trials only.

Grade CSemen quality and live births in men with idiopathic infertilityMale fertilityBetter sperm counts and motilityRCT
n 80 · 2026

Improved LH and FSH rose, sperm concentration and progressive motility improved and sperm DNA fragmentation fell only with T. chuii; live-birth rates were higher than with placebo. Semen values drifted back toward baseline after stopping.

Design: RCT, n = 80, 2026
Population: Men with idiopathic infertility (Spain)
Form: SOD-rich Tetraselmis chuii ingredient vs placebo
Dose: 250 mg/day
Duration: 3 months, then 3-month wash-out
Source: Reference 1 · PubMed 42093254 (opens PubMed)

Grade DBody composition, hormones and blood countsBody compositionSmall body-composition changesRCT
n 46 · 2022

Improved Both doses raised muscle percentage, erythropoietin, IGF-1, free testosterone and white cells and lowered fat percentage, platelets and haematocrit; the authors judged 25 mg/day most effective.

Design: RCT, n = 46, 2022
Population: Healthy young men (Spain)
Form: T. chuii vs lactose placebo
Dose: 25 or 200 mg/day
Duration: 60 days
Source: Reference 3 · PubMed 35627597 (opens PubMed)

Grade DAerobic fitness and blood values in soccer playersEnduranceHigher VO2max vs own baselinePilot RCT
n 32 · 2020

Improved Within the supplemented group, VO2max rose from 53.56 to 56.74 mL/kg/min and haemoglobin from 15.12 to 16.58 g/dL; heart rate fell.

Design: Pilot RCT, n = 32, 2020
Population: Amateur male soccer players (Spain)
Form: T. chuii vs lactose placebo
Dose: 200 mg/day
Duration: 30 days
Source: Reference 5 · PubMed 32967151 (opens PubMed)

Grade DStrength recovery and salivary IgA after hard resistance trainingExercise recoveryLess loss of explosive strengthRCT
n 22 · 2021

Improved T. chuii prevented the drop in peak rate of force development seen with placebo, and salivary IgA fell with placebo but not with T. chuii.

Design: RCT, n = 22, 2021
Population: Healthy men and women (US)
Form: Marine phytoplankton (Oceanix, T. chuii) vs placebo
Dose: 25 mg/day
Duration: 14-day loading, then 5 training days
Source: Reference 4 · PubMed 33887828 (opens PubMed)

Grade DPerceived recovery and jump power during overreaching resistance trainingExercise recoveryFaster return of explosive strengthRCT
n 22 · 2021

Improved Perceived recovery improved at post-testing with T. chuii. Explosive jump output (peak and mean rate of force development) dropped in both groups after the overreaching weeks, then returned to baseline with T. chuii but stayed lower with placebo.

Design: RCT, n = 22, 2021
Population: Regularly exercising men and women aged 18–45 (US)
Form: Marine phytoplankton (Oceanix, T. chuii) vs placebo
Dose: 25 mg/day
Duration: 5-week training programme with two overreaching weeks
Source: Reference 9 · PubMed 33352600 (opens PubMed)

Grade DMuscle damage and performance after a strenuous cross-training eventExercise recoveryLess muscle damage after hard exerciseRCT
n 18 · 2020

Improved Squat-jump power was 15% lower with placebo than with T. chuii 24 hours after the event, isometric strength fell more with placebo (−12%), and serum creatine kinase was 14% higher with placebo.

Design: RCT, n = 18, 2020
Population: Endurance-trained adults running about 30 miles a week (US)
Form: Marine phytoplankton (Oceanix, T. chuii) vs placebo
Dose: 25 mg/day
Duration: 14 days (event on day 12)
Source: Reference 8 · PubMed 32635494 (opens PubMed)

Grade DPeak oxygen uptake and muscle antioxidant genesEnduranceHigher VO2peak vs baselineCrossover RCT
n 13 · 2025

Improved VO2peak rose after T. chuii compared with its own baseline but not after placebo; muscle biopsies showed higher expression of NRF2 and antioxidant enzyme genes vs placebo. No side effects were reported.

Design: Crossover RCT, n = 13, 2025
Population: Healthy young men (UK)
Form: SOD-rich T. chuii vs placebo
Dose: 25 mg/day
Duration: 14 days per period
Source: Reference 2 · PubMed 40298824 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

One supplier behind the data

All five human trials were funded by, co-authored by or supplied by Fitoplancton Marino, Lonza or Fertypharm. Independent trials would be needed before the findings can be trusted.^1,2,3,4,5

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from 25 mg/day for 2-9 weeks in exercise and recovery studies to 200 mg/day for 30-60 days and 250 mg/day for 3 months in infertile men. These are research doses, not recommendations.^{2,3,4,5,1,8,9}

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Tetraselmis chuii and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Tetraselmis chuii.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

3 groups

Pregnancy and breastfeeding: NCCIH notes that many dietary supplements have not been tested in pregnant women or nursing mothers, and no trial of Tetraselmis chuii enrolled them.⁷
Men under fertility care: In the infertility trial, LH and FSH rose with supplementation. Anyone on hormone or fertility treatment should be aware that hormone tests may shift.¹
People on medicines: No drug-interaction studies have been published; the trials enrolled mostly healthy young adults, so effects with blood thinners, diabetes drugs or other medicines are unknown.^2,3,4,5

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

8 answers

Does Tetraselmis chuii improve endurance?

Two small trials reported higher VO2peak or VO2max after 2-4 weeks, but both compared results with each group's own baseline. Larger independent trials are lacking.^2,5

Does it help male fertility?

One 80-man placebo-controlled trial found better sperm concentration, motility and DNA integrity and more live births; the DNA benefit was clearest in men with high seminal oxidative stress. It was company funded and has not been replicated.¹

Does Tetraselmis chuii help exercise recovery?

Three small trials of 25 mg/day, each with a co-author from the ingredient's seller, reported less strength loss or muscle damage after hard training than placebo. Each had only 18–22 participants who finished, so the evidence is grade D.^4,8,9

How much was used in studies?

Very little: 25 mg/day in most exercise trials, 200 mg/day in two Spanish trials and 250 mg/day in the fertility trial.^1,2,3,5

Does it interact with medicines?

No drug-interaction studies have been published. Trials enrolled mostly healthy young adults, so effects with blood thinners, diabetes drugs or other medicines are unknown.^2,3,4,5

Is Tetraselmis chuii safe during pregnancy or breastfeeding?

There are no data. No trial enrolled pregnant or breastfeeding women, and NCCIH notes that many supplements have not been tested in these groups.^7,1

Is it the same as spirulina or chlorella?

No. It is a different marine green microalga, used at milligram doses for its antioxidant enzyme content rather than as a protein source.⁶

What is TetraSOD?

A trade name for an SOD-rich ingredient made from the microalga Tetraselmis chuii; Oceanix is another brand of the same species.^2,4

Sources

9 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

9 sources

1Superoxide Dismutase-Rich Tetraselmis chuii Supplementation Improves Semen Quality in Idiopathic Infertile Males: A Double-Blind Randomized Placebo-Controlled Trial.RCT World J Mens Health, 2026 · PMID 42093254
2Tetraselmis chuii Supplementation Increases Skeletal Muscle Nuclear Factor Erythroid 2-Related Factor 2 and Antioxidant Enzyme Gene Expression, and Peak Oxygen Uptake in Healthy Adults: A Randomised Crossover Trial.Crossover RCT Antioxidants (Basel), 2025 · PMID 40298824
3Effects of Tetraselmis chuii Microalgae Supplementation on Anthropometric, Hormonal and Hematological Parameters in Healthy Young Men: A Double-Blind Study.RCT Int J Environ Res Public Health, 2022 · PMID 35627597
4Marine phytoplankton improves recovery and sustains immune function in humans and lowers proinflammatory immunoregulatory cytokines in a rat model.RCT Phys Act Nutr, 2021 · PMID 33887828
5Effects of Tetraselmis chuii Microalgae Supplementation on Ergospirometric, Haematological and Biochemical Parameters in Amateur Soccer Players.Pilot RCT Int J Environ Res Public Health, 2020 · PMID 32967151
6The Potential of Superoxide Dismutase-Rich Tetraselmis chuii as a Promoter of Cellular Health.Review Int J Mol Sci, 2025 · PMID 40004157
7Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
8Phytoplankton Supplementation Lowers Muscle Damage and Sustains Performance across Repeated Exercise Bouts in Humans and Improves Antioxidant Capacity in a Mechanistic Animal.RCT Nutrients, 2020 · PMID 32635494
9Marine Phytoplankton Improves Exercise Recovery in Humans and Activates Repair Mechanisms in Rats.RCT Int J Sports Med, 2021 · PMID 33352600

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026evidence, studied doses, FAQ	Added two small placebo-controlled exercise-recovery trials of 25 mg/day (PMIDs 32635494 and 33352600, completer numbers from PMC full text) and three FAQ items (exercise recovery, interactions, pregnancy). PubMed search 2023–2026 found no newer human trials beyond the 2025 and 2026 trials already listed. Interactions re-checked: NCCIH and PubMed list none for this ingredient, so the list stays empty and the FAQ says so. Fact-checked against the sources; corrected: removed the 2020 cross-training trial (PMID 32635494) as a source for "no side effects reported", since it did not report on side effects, and reworded the recovery FAQ to say 18–22 participants finished each trial rather than enrolled.	Writer: Kymata Health EditorialTrigger: A–Z page audit
Oct 14, 2026who should avoid	Pregnancy and breastfeeding caution re-sourced to NCCIH (agency source) instead of trial reports	Writer: Kymata Health EditorialTrigger: adversarial review
Oct 14, 2026all	Initial editorial evidence review	Writer: Kymata Health EditorialTrigger: new page

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