Docosahexaenoic acid and the brain- what is its role?

Docosahexaenoic acid (DHA) is a 22-carbon omega 3 PUFA highly enriched in the neuronal cell membranes and rod outer segment membranes. When DHA is depleted from these cell membranes it is replaced nearly quantitatively by a 22-carbon omega 6 PUFA, docosapentaenoic acid, which has similar, but less potent, biophysical and physiological properties to DHA. It is speculated that omega 6-docosapentaenoic acid is a buffer to prevent the possible catastrophic effects of DHA depletion on brain and visual function. The primary insult from the loss of DHA from cell membrane glycerophospholipids, and replacement by omega 6-docosapentaenoic acid, is on the flexibility/compression of the membrane lipids which affects the optimal function of integral membrane proteins (receptors, voltage-gated ion channels and enzymes). This leads to effects on second messenger systems, and subsequently affects neurotransmitter concentrations due to 'weakened' signals from the initiating receptors. Remembering there are more than 80 billion neurones and many times more synaptic connections between neurons, a very small loss of "efficiency" in signal due to altered properties of membrane proteins would likely result in meaningful changes in brain and visual function. Additionally, impairment of neurotransmission could be due, in part, to sub-optimal brain energy metabolism (glucose entry into the brain), which is significantly reduced in omega 3 deficiency. Many studies report that dietary omega 3 deficiency results in changes in learning, coping with stress, behavioural changes, and responses in visual function. It is thus concluded that DHA is an essential fatty acid for optimal neuronal function.

Development of nutrition science competencies for undergraduate degrees in Australia.

BACKGROUND AND OBJECTIVES: The need for updated competencies for nutrition scientists in Australia was identified. The aim of this paper is to describe the process of revising of these competencies for undergraduate nutrition science degrees in Australia. METHODS AND STUDY DESIGN: An iterative multiple methods approach comprising three stages was undertaken: 1. Scoping study of existing competencies; 2. Exploratory survey; and, 3. Modified Delphi process (2 rounds) involving 128 nutrition experts from industry, community, government and academia. A ≥70% consensus rule was applied to Rounds 1 and 2 of the Delphi process in order to arrive at a final list of competencies. RESULTS: Stage 1: Scoping study resulted in an initial list of 71 competency statements, categorised under six core areas. Stage 2: Exploratory survey-completed by 74 Nutrition Society of Australia (NSA) members; 76% agreed there was a need to update the current competencies. Standards were refined to six core areas and 36 statements. Stage 3: Modified Delphi process-revised competencies comprise five core competency areas, underpinned by fundamental knowledge, skills, attitudes and values: Nutrition Science; Food and the Food System; Nutrition Governance, Sociocultural and Behavioural Factors; Nutrition Research and Critical Analysis; and Communication and Professional Conduct; and three specialist competency areas: Food Science; Public Health Nutrition; and Animal Nutrition. CONCLUSIONS: The revised competencies provide an updated framework of nutrition science knowledge for graduates to effectively practice in Australia. They may be used to benchmark current and future nutrition science degrees and lead to improved employability skills of nutrition science graduates.