James Lind Alliance research priorities: what role do carbohydrates, fats and proteins have in the management of Type 2 diabetes, and are there risks and benefits associated with particular approaches?

AIMS: To assess the role played by carbohydrates, fat and proteins in the management of Type 2 diabetes. BACKGROUND: Diabetes research tends to reflect the interests of academics or the pharmaceutical industry, rather than those of people living with Type 2 diabetes. The James Lind Alliance and Diabetes UK addressed this issue by defining the research priorities of people living with Type 2 diabetes. Three of the top 10 research priority questions focused on lifestyle. METHODS: A narrative review was undertaken with a structured search strategy using three databases. Search terms included the three macronutrients and Type 2 diabetes. No restrictions were placed on macronutrient quantity or length of study follow-up. Outcomes included changes in HbA1c , body weight, insulin sensitivity and cardiovascular risk. RESULTS: There is no strong evidence that there is an optimal ratio of macronutrients for improving glycaemic control or reducing cardiovascular risk. Challenges included defining the independent effect of macronutrient manipulation and identifying the effects of macronutrients, independent of foods and dietary patterns. Extreme intakes of macronutrients may be associated with health risks. CONCLUSIONS: It is challenging to formulate food-based guidelines from studies based on macronutrient manipulation. Structured education should be offered to support individuals in discovering their optimal, individual dietary approach. Recommendations for dietary guidelines should be expressed in terms of foods and not macronutrients.

Dietary intake in people consuming a low-carbohydrate diet in the UK Biobank.

BACKGROUND: Low-carbohydrate diets are becoming increasingly popular, although their dietary quality outside of clinical studies is unknown. A previous study analysed the dietary intake in people consuming a reduced-carbohydrate diet (<40% calories). However, it is not clear what foods people consume when carbohydrate is reduced to below 26% of total calories. METHODS: In the present cross-sectional study, the dietary and nutrient intake collected via up to five consecutive 24-h dietary recalls and a food frequency questionnaire of 444 individuals (aged 46-79 years) consuming <26% of calories from carbohydrate (LCHO) was compared with that of 131 897 individuals consuming ≥45% calories from carbohydrate (NCHO) using the UK Biobank Dataset. Absolute cut-offs to define the low-carbohydrate group (<130 g day-1 ; n = 1953 versus ≥225 g day-1 , n = 113 036) were also used. RESULTS: Both NCHO (>45% calories and ≥225 g) groups consumed significantly more high-sugar, high-fat snacks [median 6.0, interquartile range (IQR) = 2.0-11.0 and median 6.0, IQR = 3.0-11.8, respectively) compared to the LCHO (<26% calories and <130 g) groups (median 0, IQR = 0-2.8 and median 1, IQR = 0-3.8, respectively) (P < 0.0001). Both LCHO groups reported consuming significantly more red meat, oily fish, nuts and seeds but fewer fruits, vegetables and pulses compared to the NCHO groups. In general, the consumption of oily fish, nuts, seeds and pulses was low across the whole cohort and differences in intake between the LCHO and NCHO groups were small. After adjusting for socio-economic status, most differences remained. CONCLUSIONS: Carbohydrate restriction is associated with both beneficial and potentially deleterious dietary changes compared to a normal carbohydrate intake.

Dietary intake in people consuming a reduced-carbohydrate diet in the National Diet and Nutrition Survey.

BACKGROUND: Diets reduced or low in carbohydrates are becoming increasingly popular. The replacement foods and their accompanying nutrients determine the health effects of such diets. However, little is known about the dietary intake of people consuming reduced or low carbohydrate diets. METHODS: In this cross-sectional study, the dietary and nutrient intake of individuals aged 16-75 years consuming less than 40% of energy from carbohydrate (n = 430) was compared with individuals consuming equal to or more than 40% energy from carbohydrate (n = 1833) using the UK National Diet and Nutrition Survey. RESULTS: Those consuming less than 40% of total energy from carbohydrate reported a higher consumption of red and processed meat, butter, oily fish and vegetables, as well as a lower consumption of soft drinks and pulses, than those with a normal carbohydrate intake. After adjusting for socio-economic status, only red meat intake was different between the groups, and reached the maximum recommended daily intake daily intake. There were no significant differences in micronutrient intakes between the groups, although magnesium, selenium and potassium, along with fibre, were lower than recommended amounts across the cohort. CONCLUSIONS: Individuals consuming reduced or low carbohydrate diets could benefit from replacing some red meats with white meats and vegetable sources of protein, and increasing vegetable intake.

Improvements in stage of change correlate to changes in dietary intake and clinical outcomes in a 5-year lifestyle intervention in young high-risk Sri Lankans.

The objectives of a stage-matched approach to lifestyle change are that individuals progress forward through the stages of change. It also posits that progression through the stages of change is associated with positive changes in lifestyle behaviours. Measuring the relationship between stage of change and food intake is challenging due to the plurality of dietary behaviours. Furthermore, it is not clear whether changes in behaviour are sustained long-term. In this study we assess the movement through stages of change in the intensive (visits every 3months) and control groups (visits annually) of a large-scale primary prevention study in cardiovascular disease, carried out in 2637 children and young adults in Sri Lanka between 2007 and 2012. We also examine their relationship to dietary behaviours and clinical outcomes. We demonstrate that individuals in both groups continue to progress through stages of change over the course of the study and that measures of dietary behaviours improved from baseline to final follow-up. We also demonstrate that stage of change positively correlates to dietary behaviours including the ratio of recommended:not-recommended items, unpolished:polished starches and low-fat:high-fat food items throughout each year of the study. Finally, participants in the later stages of change at Y2, Y3 and Y4, had a significantly attenuated increase in weight and waist circumference at the final visit in both groups. We therefore demonstrate the usefulness of stage-matched approach in modifying complex dietary behaviours, and that stage of change is a valid measure of dietary behaviours across a large population over time.