DHA (docosahexaenoic acid) is one of the most important nutrients when it comes to supporting the health of the brain. As a key component of omega-3 fatty acids, DHA plays a foundational role in the maintenance of brain function.
Unlike other fats in the diet, DHA isn’t just a source of energy—it’s part of the brain’s architecture. It supports the way we think, feel, and adapt, and emerging research continues to highlight its influence on mood, memory, and overall emotional resilience.
In this article, we’ll explore the science behind DHA’s impact on mental wellbeing, from its role in neurotransmitter function to its influence on cognitive ageing.
What is DHA and Where Is It Found?
DHA is a long-chain omega-3 fatty acid found mainly in marine sources such as salmon, mackerel, sardines, and anchovies. Smaller amounts are present in algae, which is the original source of DHA in the marine food chain. High-quality fish oil or algae-based supplements are also commonly used to support intake.
While plant-based omega-3s like ALA (from flax, chia, or walnuts) have some health benefits, the body must convert ALA into DHA—a process that’s highly inefficient. On average, less than 5% of ALA is converted, and this depends on factors like age, hormones, and overall health.
The Brain’s Preference for DHA
The human brain is made up of around 60% fat, and of that fat, DHA is the most abundant omega-3 found in grey matter . It is highly concentrated in the membranes of neurons, where it plays a vital role.
These membranes aren't static—they’re constantly adapting to the needs of the body and brain. When they contain adequate DHA, neurons are better able to receive and transmit signals, supporting processes like memory, emotional regulation, and executive function. Put simply, DHA helps brain cells “talk” to one another more effectively.
DHA and Mood Regulation
Multiple scientific studies have explored the role of DHA in supporting emotional wellbeing, particularly through its influence on neurotransmitter systems and inflammation in the brain.
- Neurotransmitter function: DHA helps regulate the release and activity of key brain chemicals such as serotonin and dopamine . These neurotransmitters are closely linked with emotional balance, motivation, and reward. Some evidence suggests that DHA improves receptor sensitivity, making it easier for these chemical messages to be received and acted upon.
- Reducing neuroinflammation: DHA has been shown to reduce pro-inflammatory cytokines can lower levels of pro-inflammatory cytokines such as TNF-α and IL-6 in the brain and support the production of specialised pro-resolving mediators (SPMs), which help to attenuate neuroinflammation in the hippocampus region of the brain. A 2021 review published in Nutrients highlighted DHA’s neuroprotective effect, particularly in areas of the brain associated with emotional processing.
- HPA axis regulation: The hypothalamic-pituitary-adrenal (HPA) axis governs the body’s response to stress. DHA may help regulate this system, reducing the impact of prolonged stress on mental wellbeing. By helping to modulate the release of cortisol , DHA may support a more balanced response to external demands.
Cognitive Resilience and Brain Ageing
Beyond mood, DHA plays a key role in maintaining cognitive function throughout life. Numerous studies have found a link between higher blood levels of DHA and better cognitive performance —especially in areas such as memory, attention, and processing speed.
Studies show that older adults with higher DHA levels performed better on memory and learning tests and had greater brain volume in key cognitive regions. This is particularly significant, as the natural ageing process tends to reduce both brain DHA content and cognitive flexibility over time.
By maintaining membrane integrity and reducing oxidative stress, DHA may help protect neurons from age-related damage, supporting long-term brain health.
DHA and Hormonal Mental Health
Hormonal changes—especially during perimenopause and postmenopause—can affect neurotransmitter balance, brain energy metabolism, and emotional resilience. Oestrogen, which has well documented neuroprotective and mood-supportive effects, declines during this transition, and many women notice shifts in cognition and mood as a result.
DHA may offer targeted support during menopause, particularly for brain health. It plays a role in maintaining synaptic plasticity—the brain’s ability to form and adapt neural connections—which underpins learning, memory, and emotional flexibility. A 2022 review published in Nutrients discussed the role of omega-3 polyunsaturated fatty acids (PUFAs), including DHA, in cognitive health during menopause. It referenced findings where supplementation with EPA and DHA improved verbal memory and reduced psychomotor response time in postmenopausal women, suggesting a beneficial effect during this hormonally dynamic phase.
Dietary Sources and Supplementation
For most people, aiming for two to three servings of oily fish per week can provide a meaningful amount of DHA. Examples include:
- Salmon (wild-caught if possible)
- Sardines
- Mackerel
- Anchovies
For those who eat little to no fish, high-quality supplements—such as fish oil or algae-based DHA—can be a convenient and effective way to support intake. Algae-derived supplements are especially useful for individuals following a vegetarian or vegan diet.
Putting DHA into Practice
DHA is a structural and functional cornerstone of the brain. From modulating neurotransmitters that influence motivation and mood, to supporting memory and learning through all life stages, its role in mental wellbeing is well-established.
While oily fish is the most reliable food source, supplements—particularly algae-based options for those following a plant-based diet—can be a practical way to support intake where diet falls short.
Understanding how DHA works allows us to make more informed choices about the foods and nutrients we prioritise. In doing so, we’re not just supporting the brain—we’re supporting the way we engage with the world, adapt to life’s demands, and maintain a sense of emotional balance.
*The advice in this article is for information only and should not replace medical care. As with any nutritional supplement please consult your qualified healthcare professional before use, especially if pregnant, breastfeeding, if you have a known medical condition or are taking medication. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.
Genna Nelson
Nutritional Therapist and GN Wellness
