Predictors and change in dietary behaviours among young men : an intervention in the military
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AbstractYoung men are difficult to reach with conventional nutrition information and they have a low intake of vegetables and fruits and whole grain cereals. The low intake of these foods gives rise to concern about their future health. Few intervention studies have focused on improving young men’s consumption of vegetables, fruits and whole grain cereals and few studies have explored important correlates of young men’s intake of vegetables.
This study is a part of a larger project with the aim to improve the diet among young men in the military by offering a combination of nutritional information and increased availability of vegetables, fruits and whole grain cereals. The present thesis presents the results from a sub study of the larger project. Since the knowledge base on dietary perceptions and behaviour in the target group is weak, the objectives were to first explore factors that may influence young men’s food intake, and then to investigate changes in intake of selected foods and nutrients as well as reflected changes in a biomarker after a dietary intervention. The focus was directed to the foods that were targeted in the intervention: vegetables, fruits and whole grain cereals, with special emphasis on vegetables. The biomarker was plasma homocysteine.
The study included male recruits at Værnes Military Training Centre in the intervention group; 578 recruits at baseline and 376 at follow up. The control group consisted of 105 male recruits at The Norwegian Army, Bardufoss. The dietary intervention programme was a combination of nutritional information and increased availability of vegetables, fruits and whole grain cereals and lasted for five months.
The results from the baseline showed that the recruits in the intervention group had an average intake of vegetables of 244 g/day, of which 43% was potatoes. There was a large variation in the intake of vegetables among the recruits in spite of the fact that the recruits ate most of their meals in the military mess hall. Only 6% of the recruits reached an intake of 450 g of vegetables daily, which was recommended at the time of the study. The most important sources of vegetables were the hot composite dishes served for lunch and dinner. Optimistic bias of own vegetable intake was observed, since nearly one-third of the recruits perceived their intake as sufficient. The recruits reported high preferences for vegetables: 78% reported a liking for raw vegetables, and 58% for cooked vegetables.
The recruit’s intake of vegetables at baseline was positively associated with number of hot meals eaten in the military mess hall, a high intake of vegetables when still living at home, their parent’s socio economic status and high scores on taste preferences for cooked vegetables. Weight beliefs (desire for slenderness) were also positively associated, while social influence and smoking habits were negatively associated with the recruit’s intake of vegetables. These correlates explained 32% of the variance in the recruit’s vegetable intake.
Three different food intake patterns were discerned in a principal component analysis, based on the intake data collected among the recruits in the intervention group at baseline. These were called: 1) plant foods, 2) fast food/soft drinks and 3) milk/cereals, explaining 42% of the variance in the intake. The desire for slenderness was positively related to level of physical activity but not to the food intake patterns. However, BMI was related to food intake pattern; those who scored high on the plant food pattern were less likely to have a high BMI.
After the intervention, a significant change in intake was observed for the food items which were in focus in the intervention. The recruits in the intervention group increased their consumption of vegetables with 55 %, whole grain bread with 29 % and fruits with 12 %. The increases in the intervention group were significantly different from the control group for all these food items. The increased intakes were reflected in increased intake of folate and dietary fibre. Concomitantly, a reduction in plasma total homocysteine (p-tHcy) was observed. The reduction in p-tHcy was significantly related to an increased intake of folate from whole grain bread but not to that from vegetables, fruits and juice. Furthermore, the percentage of recruits who had three out of four correct answers on the nutritional knowledge score increased from 5% to 25% during the intervention. The recruits with increased knowledge scores had increased their vegetable intake more than the others.
In conclusion, behavioural factors were most important in explaining the recruit’s intake of vegetables. The dietary intervention with both increased availability and easily understood nutritional messages, turned out to be effective in increasing the intake of vegetables, fruits and bread among young male recruits. This was reflected in increased intake of both dietary fibre and folate and a reduction in plasma homocysteine. This study has contributed to information on important correlates of vegetable intake and effective strategies for increasing the consumption of healthy food items among young men.
List of papers. Papers I, II and IV are removed from the thesis due to copyright restrictions.
Paper I Preferences and perceptions of personal vegetable consumption: A study among young men in the Norwegian National Guard. Uglem S, Frølich W, Stea TH, Wandel, M. International Journal of Food Sciences and Nutrition. 2008; 59 (4): 279-290 doi:10.1080/09637480701496651
Paper II Correlates of vegetable consumption among young men in the Norwegian National Guard. Uglem S, Frølich W, Stea TH, Wandel, M. Appetite. 2007; 48 (1): 46-53. doi:10.1016/j.appet.2006.06.005
Paper III Body weight, weight perceptions and food intake patterns. A cross-sectional study among male recruits in the Norwegian National Guard. Uglem S, Stea TH, Frølich W, Wandel, M. BMC Public Health. 2011; 11: 343 doi:10.1186/1471-2458-11-343 Published under the terms of the Creative Commons Attribution License
Paper IV A nutrition intervention focusing on vegetables, fruit and bread among young men Uglem S, Stea TH, Kjøllesdal MK, Frølich W, Wandel, M. Submitted
Paper V Association between folate intake from different food sources in Norway and homocysteine status in a dietary intervention among young male adults. Stea TH, Uglem S, Wandel, M, Mansoor MA, Frølich W. British Journal of Nutrition, 2009; 102 (6): 899-906. doi:10.1017/S0007114509301580