Evangeline Mantzioris

A practical approach to increasing intakes of n-3 polyunsaturated fatty acids: use of novel foods enriched with n-3 fats.

Objectives: To assess the effects of providing a wide range of foodstuffs containing n-3 polyunsaturated fatty acids (PUFA), occurring naturally or from fortification, on intake and blood and tissue proportions of n-3 PUFA.Design: Before/after dietary intervention study.Setting: Adelaide, Australia.Subjects: 16 healthy males recruited from the community.Interventions: Subjects were provided with a range of foodstuffs naturally containing n-3 PUFA (fresh fish, canned fish, flaxseed meal, canola oil) and items fortified with fish oil (margarine spread, milk, sausages, luncheon meat, french onion dip). Food choices were left to the discretion of each subject. Intake was estimated by diet diary. Blood was collected at—2, 0, 2, and 4 weeks for fatty acid analysis.Main outcome measures: Dietary intakes; plasma, platelet, and mononuclear cell phospholipid fatty acids.Results: Consumption of n-3 PUFA increased significantly: α-linolenic acid (ALA) from 1.4 to 4.1 g/day (P<0.001), eicosapentaenoic acid (EPA) from 0.03 to 0.51 g/day (P<0.001), and docosahexaenoic acid (DHA) from 0.09 to 1.01 g/day (P<0.001). Linoleic acid (LA) intake decreased from 13.1 to 9.2 g/day (P<0.001). The proportions of EPA and DHA increased significantly in all phospholipid pools examined; plasma EPA from 1.13% of total fatty acids to 3.38% (P<0.001) and DHA from 3.76 to 7.23% (P<0.001); mononuclear cell EPA from 0.40 to 1.25% (P<0.001) and DHA from 2.33 to 4.08% (P<0.001); platelet EPA from 0.41 to 1.2% (P<0.001) and DHA from 1.64 to 3.07% (P<0.001).Conclusions: Incorporating fish oil into a range of novel commercial foods provides the opportunity for wider public consumption of n-3 PUFA with their associated health benefits.Sponsorship: Dawes Scholarship, Royal Adelaide Hospital.

Ratios of linoleic acid to α-linolenic acid in formulas for term infants

Commercial infant formulas with a ratio of linoleic acid (LA) to a-linolenic acid (ALA) of 10:1 or higher are nutritionally inadequate; the tissue levels of docosahexaenoic acid (DHA) are lower and the visual function indices are reduced in infants who are fed these formulas. All the evidence points to using LA:ALA ratios of less than 8:1, but there has been only one study in infants that used formulas with reduced LA:ALA ratios, and only biochemical indices were monitored. There is a need for both short-term studies to establish the ratios of LA to ALA that will make possible the accumulation of DHA to levels close to those in breast-fed infants and long-term trials to determine the effects of such fat blends on growth and development.

A low omega-6 polyunsaturated fatty acid (n-6 PUFA) diet increases omega-3 (n-3) long chain PUFA status in plasma phospholipids in humans.

This study aimed to determine the effect of reducing the dietary linoleic acid (LA) intake from ~5% to <2.5% energy (%E) on n-3 long chain PUFA (LCPUFA) status in humans. Thirty-six participants followed a <2.5%E LA diet for 4 weeks. Nutrient intakes were estimated from diet diaries and blood samples were collected for assessment of fatty acid composition in plasma and erythrocyte phospholipids. LA intakes were reduced from 4.6%E to 2%E during the low LA intervention (P<0.001) while n-3 LCPUFA intakes were unchanged. LA and total n-6 PUFA content of plasma and erythrocyte phospholipids were significantly reduced after the low LA diet phase (P<0.001). The n-3 LCPUFA content of plasma phospholipids was significantly increased after the low LA diet compared to baseline (6.22% vs. 5.53%, P<0.001). These data demonstrate that reducing LA intake for 4 weeks increases n-3 LCPUFA status in humans in the absence of increased n-3 LCPUFA intake.

The effect of modifying dietary LA and ALA intakes on omega-3 long chain polyunsaturated fatty acid (n-3 LCPUFA) status in human adults: a systematic review and commentary.

This paper presents a systematic review of human studies investigating the effect of altering dietary omega-3 polyunsaturated fatty acid (n-3 PUFA) alpha-linolenic acid (ALA) and omega-6 polyunsaturated fatty acid (n-6 PUFA) linoleic acid (LA) intakes on n-3 long-chain polyunsaturated fatty acid (LCPUFA) status in adult humans. The results suggest that it is possible to increase n-3 LCPUFA status by reducing LA and/or increasing ALA intake in humans, although decreasing LA intake to below 2.5%E may be required to specifically increase levels of the n-3 LCPUFA docosahexaenoic acid (DHA). The majority of studies in this area to date have been relatively poor in quality, which limits the ability to draw robust conclusions, and we present a series of recommendations to improve the quality of future studies in fatty acid nutrition in humans.

Differences in the interpretation of a modernized Mediterranean diet prescribed in intervention studies for the management of type 2 diabetes: how closely does this align with a traditional Mediterranean diet?

Purpose and MethodsAdherence to Mediterranean diet (MedDiet) is associated with the prevention and management of type 2 diabetes mellitus (T2DM). However, in intervention studies, there is discordance in the interpretation of a MedDiet. The purpose of this paper was to examine, synthesize, and develop a narrative review, exploring the qualitative differences in the interpretation of a modernized MedDiet prescribed as an intervention in clinical trials for the management of T2DM, and how closely this aligns with a traditional MedDiet. The ‘traditional’ MedDiet is often described as a dietary pattern high in unprocessed plant foods (fruits, vegetables, legumes, nuts, wholegrain cereals, and olive oil); moderate consumption of wine; low moderate in fish/shellfish; and an infrequent consumption of red meat, animal fats, vegetable oils, and processed foods.Results and ConclusionsSynthesis of the reviewed literature demonstrates considerable variation in the qualitative interpretation of a MedDiet. We also identified inadequate reporting of MedDiet interventions, despite a number of studies referring to their intervention as a ‘traditional’ MedDiet. The majority of studies emphasized the same key dietary components and principles: an increased intake of vegetables, wholegrains, and the preferential consumption of white meat in substitute of red and processed meat and abundant use of olive oil. However, the reporting of specific dietary recommendations for fruit, legumes, nuts, bread, red wine, and fermentable dairy products were less consistent or not reported. Irrespective of the discordance in the interpretation of a MedDiet, a number of studies included in the present review reported improved glycaemic control and favorable cardiovascular outcomes with adherence to a Mediterranean-style diet. Nevertheless, greater clarity and depth of reporting amongst intervention studies is warranted for the refinement of a modernized MedDiet definition that is distinct from a prudent dietary pattern.