When trying to conceive, the question of optimal nutrient intake moves to the fore. Omega-3 fatty acids — in particular EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) — are attracting increasing attention in reproductive medicine. Studies suggest that these polyunsaturated fatty acids may influence several aspects of reproductive capacity: from egg quality to endometrial function and sperm quality in men. This article outlines what research shows about omega-3 and fertility, which mechanisms are being discussed, and what to bear in mind during this sensitive phase. As always: discuss all supplements with your doctor — especially if you are planning medically assisted treatments such as IVF.
Why might omega-3 play a role when trying to conceive?
Omega-3 fatty acids are not only relevant for cardiovascular health and brain function — they are components of every cell in the body and influence numerous hormonal and inflammation-related processes. These processes also play a role in reproductive biology. Broadly speaking, three main areas of action can be identified in which omega-3 might influence fertility:
- Cell membrane function: DHA is a central component of cell membranes, including those of eggs and sperm. The fluidity and function of these membranes may influence fertilisation capacity.
- Inflammation modulation: Chronic subclinical inflammation can impair embryo implantation and endometrial function (uterine lining). Omega-3 modulates inflammatory processes through the formation of anti-inflammatory eicosanoids.
- Hormonal balance: Omega-3 may influence the synthesis of prostaglandins, which are involved in ovulation, menstrual regulation and uterine contractility.
Important note on the scientific evidence
Research into omega-3 and fertility is at an earlier stage compared to other omega-3 indications (cardiovascular health, preterm birth prevention). Many studies are observational in nature or were conducted with small samples. Large randomised controlled trials on clinically relevant fertility outcomes are so far fewer in number. The findings presented here should be understood as indicators, not as conclusive causal proof.
Omega-3 and female fertility
Egg quality and ovarian reserve
Several studies have investigated the relationship between a woman's omega-3 status and the quality of her eggs. Observational studies in women undergoing assisted reproduction (IVF/ICSI) suggest that women with higher DHA content in follicular fluid — the fluid surrounding the maturing egg — more frequently had good embryo quality and successful fertilisations. These relationships are biologically plausible, as eggs are rich in DHA and require it for membrane integration and egg cell energy metabolism.
A prospective cohort study in IVF patients found that higher dietary omega-3 intake was associated with better clinical outcomes, including higher fertilisation rates and a trend towards more live births. However, causal conclusions cannot be drawn from such observational studies, as numerous confounding factors may play a role.
Endometrium and implantation
The endometrium — the uterine lining — must be receptive to the embryo within a specific time window for implantation to occur. Animal studies show that diets rich in omega-3 may improve uterine receptivity, partly through modified prostaglandin synthesis. Early indications from clinical studies in humans point in a similar direction, but are not yet sufficient to formulate unambiguous recommendations.
PCOS (polycystic ovary syndrome)
Polycystic ovary syndrome (PCOS) is one of the most common causes of female infertility and is associated with, among other things, insulin resistance and chronic inflammation. Several small randomised studies have investigated omega-3 supplementation in women with PCOS. A meta-analysis of multiple intervention studies found that omega-3 may contribute to improvements in insulin resistance, triglycerides and inflammatory markers in PCOS patients — all factors that also indirectly influence reproductive function.
A direct improvement in ovulation rate through omega-3 in PCOS is less consistently documented in the studies. Affected women should discuss with their gynaecologist whether omega-3 supplementation is appropriate in their individual case.
Omega-3 and endometriosis
Endometriosis, in which tissue similar to the endometrium grows outside the uterus, is associated with chronic inflammation and frequently with reduced fertility. Some observational studies have detected lower omega-3 levels in women with endometriosis, and experimental animal data points to anti-inflammatory effects of omega-3. Clinical intervention studies in humans are still limited in this area.
Omega-3 and male fertility
Sperm quality and DHA
DHA is particularly concentrated in sperm cells — in the tail region of the sperm, which is decisive for motility (movement). Several studies have investigated whether men's omega-3 status is related to sperm quality.
A frequently cited observational study by Conquer et al. found that infertile men had significantly lower DHA concentrations in their sperm than fertile men. Other studies have reported similar associations between omega-3 status and sperm parameters (concentration, motility, morphology).
Omega-3 and sperm quality: analysis of multiple intervention studies
A meta-analysis of randomised studies found that omega-3 supplementation in men with reduced sperm quality may contribute to a significant improvement in sperm motility and morphology. The doses studied ranged from 1.5 g to 3 g EPA+DHA daily over periods of 3 to 6 months.
Oxidative stress and sperm DNA integrity
Sperm cells are particularly vulnerable to oxidative stress, as their cell membranes are rich in polyunsaturated fatty acids. Paradoxically, this high PUFA content — to which DHA contributes — can make membranes susceptible to oxidation. However, omega-3 fatty acids may also contribute to protecting sperm DNA through anti-inflammatory and antioxidant mechanisms. Studies on this topic show mixed results, and the net effect likely depends greatly on baseline status and intake of other antioxidants.
Omega-3 before pregnancy: the timing aspect
An important but frequently overlooked aspect is the timing of omega-3 intake. Building good omega-3 status takes time: to bring the omega-3 index — the proportion of EPA+DHA in red blood cells — to an optimal level, several weeks or months of regular supplementation are generally needed.
This means: anyone who only starts omega-3 supplementation at the beginning of pregnancy may enter the critical early phase of the child's development with suboptimal status. For this reason, many reproductive medicine specialists recommend optimising omega-3 intake during the preconception phase — that is, months before a planned pregnancy.
The omega-3 index as a reference value
The omega-3 index measures the proportion of EPA+DHA in total fatty acids of red blood cell membranes. A value of 8% or above is considered optimal, below 4% as at risk. Many people in Central European countries fall in the 5–6% range. You can find information about the omega-3 index and how to measure it in our article on the omega-3 to omega-6 ratio.
Diet and omega-3 in the preconception phase
Foods with high EPA/DHA content
The best natural source of EPA and DHA is oily sea fish. For the preconception phase, similar recommendations apply as in pregnancy: around two portions of oily sea fish per week (salmon, herring, mackerel, sardines) provide a good dietary basis. When selecting fish in the preconception phase — and especially if pregnancy is already possible — you should choose species with low mercury content.
| Food | EPA+DHA content (per 100 g) | Note |
|---|---|---|
| Atlantic salmon | approx. 2,200 mg | Good choice, low in mercury |
| Atlantic mackerel | approx. 2,500 mg | Very rich in omega-3 |
| Herring | approx. 1,700 mg | Economical, good source |
| Sardines (tinned) | approx. 1,400 mg | Convenient, low in contaminants |
| Tuna (fresh) | approx. 1,300 mg | Limit due to mercury content |
| Algae oil supplement | 200–500 mg DHA per capsule | Vegan, direct DHA source |
For vegetarians and vegans
Plant-based omega-3 sources such as linseed oil, chia seeds or walnuts contain ALA (alpha-linolenic acid), but not EPA or DHA. The conversion of ALA to EPA and DHA in the human body is very inefficient (less than 5%). Anyone following a vegan or vegetarian diet who is concerned about fertility should consider DHA supplements based on algae oil, which contain DHA directly and in some cases also EPA.
Omega-3 and medically assisted reproduction (MAR)
For couples resorting to medically assisted reproduction techniques such as IVF (in vitro fertilisation) or ICSI (intracytoplasmic sperm injection), the question arises whether omega-3 can improve the outcomes of these treatments.
Some observational studies have reported a positive association between a woman's omega-3 status and IVF outcomes, including higher fertilisation rates and better embryo quality. However, methodologically robust randomised controlled trials on this specific topic are still limited. The CARE Study (Cochrane review on omega-3 during pregnancy) included women with and without fertility problems and provided the most comprehensive evidence to date on omega-3 in the reproductive phase.
For men undergoing IVF or ICSI treatments, optimising sperm quality through omega-3 may be complementarily sensible — this should, however, be done in consultation with the reproductive medicine specialist.
Men: practical tips on omega-3 intake
Since sperm maturation takes approximately three months (spermatogenesis cycle of approx. 72–74 days), experts recommend starting to improve omega-3 intake at least three months before planned conception — or before medical reproduction procedures. This allows changes in sperm DHA content to develop and potentially improve sperm parameters.
For men, the same general dosage recommendations apply as for adults: 250–500 mg EPA+DHA daily as a baseline. Studies on male fertility frequently used higher doses (1.5–3 g daily). Here too: medical consultation before supplementation.
Summary of the scientific evidence
| Aspect | Level of evidence | Key findings |
|---|---|---|
| Egg quality (female) | Moderate | Observational studies: association between DHA in follicular fluid and embryo quality |
| Endometrial receptivity | Preliminary | Animal experimental data + early clinical indications |
| PCOS-related parameters | Moderate | Improvement in insulin, triglycerides, inflammatory markers in small RCTs |
| Sperm quality (male) | Moderate | Association studies + small RCTs: improved motility and morphology |
| IVF outcomes | Preliminary | Positive observational studies; RCTs largely lacking |
| Preterm birth prevention after conception | Very strong | Cochrane 2018: 70 RCTs, 19,927 women (PMID 30480773) |
Frequently asked questions
Can omega-3 really improve fertility?
Studies show associations between good omega-3 status and various parameters of reproductive health — in women (egg quality, hormonal balance) and in men (sperm quality). Whether omega-3 supplementation causally leads to higher pregnancy rates has not been conclusively proven scientifically. The research is, however, promising and the general safety of omega-3 is well documented.
When should I start taking omega-3 when trying to conceive?
Since building a good omega-3 index takes several weeks or months, many reproductive medicine specialists recommend starting regular omega-3 intake at least three months before planned conception. The same applies to men: sperm maturation takes approximately three months, so an early start is sensible.
What omega-3 dosage is recommended when trying to conceive?
There is currently no clear dosage recommendation specifically for the preconception phase in the form of official guidelines. As a general guide, the standard recommendation of 250–500 mg EPA+DHA daily applies as a baseline. Studies on male and female fertility frequently used higher doses (1–3 g daily). Discuss the appropriate dosage for your situation with your doctor.
Is omega-3 also relevant for men when trying to conceive?
Yes. DHA is an important component of sperm cell membranes and influences their motility and function. Studies show associations between low DHA content in sperm and reduced sperm quality. Some small intervention studies report improvements in sperm motility and morphology with omega-3 supplementation. Early optimisation of omega-3 status (at least 3 months before conception) therefore seems sensible for men too.
Which omega-3 source is best when trying to conceive?
Oily sea fish (salmon, herring, mackerel, sardines) is the most natural and nutritious source. Two portions per week cover a large part of requirements. For vegetarian or vegan diets, algae oil is the preferred alternative, as it contains DHA directly. For preconception supplements, a fish oil or algae oil verified for contaminants and without excess vitamin A is recommended.
Medical disclaimer
This article is for general information purposes only and does not replace medical advice. All study results presented are based on scientific research published up to February 2026. Research into omega-3 and fertility is ongoing — causal conclusions cannot be drawn from observational studies. Dietary supplements in the preconception phase should always be taken in consultation with a doctor, particularly during medically assisted treatments. Dietary supplements are not a substitute for a balanced diet.
Related articles: Omega-3 during pregnancy · Omega-3 during breastfeeding · Omega-3 to omega-6 ratio