Within Public Health Nutrition, the preconception phase, has emerged as a particularly important window for promoting a healthy diet, as it affects both current and future health as well as health in the next generation. Different approaches are used to support dietary change in this phase, and digital interventions are viewed as particularly promising. In this review, we describe digital interventions addressing preconception diet, discuss challenges in targeting the preconception population and highlight issues related to digital designs and measuring intervention effects. We draw upon six digital interventions with dietary outcomes, in different target populations. Only two of the interventions were found to be effective in improving relevant aspects of the participants’ diet, and these targeted specific and narrow groups or a single dietary component. Most of the intervention studies faced considerable challenges with recruitment. High attrition further complicated evaluation. In addition, there were difficulties related to participant engagement with the digital interventions. Challenges with lack of engagement, recruitment and attrition are not new insights within public health research, and we need to acknowledge the need for new approaches to recruitment, intervention development and evaluation. Alternative approaches such as citizen science and participatory action research in which the researchers work closely with the target population and other stakeholders during the whole process, should be explored. Moreover, as the current behavioural interventions that rely heavily on individual agency seem largely unsuccessful, future interventions should consider targeting more upstream and structural determinants of diet, rather than individual behaviour alone.

Military personnel generally under-consume n-3 fatty acids and overconsume n-6 fatty acids. In a placebo-controlled, double-blinded study, we investigated whether a diet suitable for implementation in military dining facilities and civilian cafeterias could benefit n-3/n-6 fatty acid status of consumers. Three volunteer groups were provided different diets for 10 weeks. Control (CON) participants consumed meals from the US Military’s Standard Garrison Dining Facility Menu. Experimental, moderate (EXP-Mod) and experimental-high (EXP-High) participants consumed the same meals, but high n-6 fatty acid and low n-3 fatty acid containing chicken, egg, oils and food ingredients were replaced with products having less n-6 fatty acids and more n-3 fatty acids. The EXP-High participants also consumed smoothies containing 1000 mg n-3 fatty acids per serving, whereas other participants received placebo smoothies. Plasma and erythrocyte EPA and DHA in CON group remained unchanged throughout, whereas EPA, DHA and Omega-3 Index increased in EXP-Mod and EXP-High groups, and were higher than in CON group after 5 weeks. After 10 weeks, Omega-3 Index in EXP-High group had increased further. No participants exhibited changes in fasting plasma TAG, total cholesterol, LDL, HDL, mood or emotional reactivity. Replacing high linoleic acid (LA) containing foods in dining facility menus with similar high oleic acid/low LA and high n-3 fatty acid foods can improve n-6/n-3 blood fatty acid status after 5 weeks. The diets were well accepted and suitable for implementation in group feeding settings like military dining facilities and civilian cafeterias.

Diet is important for the prevention of CVD, and diets high in MUFA might be more cardioprotective than low-fat diets. We hypothesise that inflammation and endothelial cell function will be improved most favourably by a high-MUFA diet compared with a low-fat diet. This was tested in a parallel randomised intervention trial on overweight individuals (aged 28·2 (sd 4·6) years) assigned to a diet moderate in the amount of fat (35–45% of energy; >20% of fat as MUFA; MUFA diet, n 39), a low-fat (20–30% of energy) diet (LF diet, n 43) or a control diet (35 % of energy as fat, n 24) for 6 months after weight loss. Protein constituted 10–20 % of energy in all diets. Food was provided free of charge. Fasting blood samples were collected before and after the intervention and analysed for C-reactive protein (CRP), IL-6, intercellular adhesion molecule, von Willebrand factor (vWF) and tissue factor pathway inhibitor. vWF concentrations tended to fall on the LF diet (4·78 (sd 16·44) %; P = 0·07). Concentrations of IL-6 were reduced by the MUFA (0·37 (sd 0·74) pg/ml; P < 0·01) and LF (0·47 (sd 0·69) pg/ml; P < 0·001) diets, and CRP was reduced on all diets (MUFA: 0·48 (sd 1·93) mg/l (P < 0·01); LF: 1·46 (sd 2·89) mg/l (P < 0·001); control: 1·20 (sd 1·97) mg/l (P < 0·01)). No significant differences were observed between changes induced by the different diets. Our findings suggest that in overweight subjects after weight loss, the MUFA and LF diets have similar long-term effects on inflammation and endothelial cell function.