The results of the review, presented in chapter 2, suggest beneficial effects of whole food in the prevention of, and shortening in duration of, upper respiratory tract infections (URTI). Some food products show clear preventive or shortening effects on URTI; e.g. kiwi, elderberry, pre- and probiotics, fish oil and garlic [1-8]. In patients with recurrent URTI, intervention with a single whole food product can therefore be beneficial. A dietary intervention with multiple food products for URTI is rarely investigated, except for the effects of the Mediterranean diet in children with recurring colds and frequent complications in Spain. This before-after study found decreased URTIs after a change in lifestyle . The effects of the Mediterranean diet are based on the concept of food synergy, meaning that the effects of a combination of foods are much stronger than the effects of single supplements with nutrients . Chapter 3 describes the effects of a nutrient rich diet, consisting of beef (3 times a week), green vegetables (5 times a week), 300 mL whole milk daily and butter, on IgE levels in children. In this retrospective case-control study in 105 children, we observed a decrease in IgE of 9.2 kU/L (= 22 ug/L) after the dietary advice had been followed for 4 months. We did not observe a change in IgE-levels in the control group. Subjective improvements in clinical complaints were recorded in 53% of the children in the intervention group and 29% in the control group (p<0.001). In chapter 4 we investigated the effect of the same dietary advice on fatigue in children. In this non-randomized controlled study in 98 children with unexplained symptoms of fatigue, the sleep domain improved in the intervention group. We evaluated every single food component (of the four in total) and its effect on fatigue in the studied population. Green vegetables improved cognitive tiredness scores significantly, while whole milk improved the sleep domain significantly. Lipid profiles in young children are scarcely investigated when there is no relation with familial dyslipidaemia. What are the consequences for the lipid profile when full fat dairy products are introduced into the diet of young children? Chapter 5 describes the results of a retrospective case-control study on the lipid profiles of children with and without the dietary advice. After 5 months, the intervention group did not show unfavourable lipid profiles. On the contrary, HDL-cholesterol (a favourable prognostic factor for cardiovascular disease) increased significantly after following the dietary advice. Also, the cholesterol/HDL ratio and the non-HDL-cholesterol improved favourably following the dietary advice. No unfavourable trends in lipid profiles were observed. In addition, the body mass index (BMI) and BMI-z scores were not adversely affected by introducing full fat dairy products together with green vegetables and beef. As part of this thesis, a randomized controlled dietary intervention was performed with a dietary change in 118 young children (1-4 years) with recurrent URTI. Again, we evaluated the dietary advice, consisting of green vegetables, beef, whole milk and butter, over 6 months. We found a significant decrease in infection days, catarrhal episodes, coughing and days with fever. Also, antibiotic use decreased by 66.6% over the 6-month period (chapter 6). No significant weight gain or increase in BMI was seen in the intervention group. Laboratory parameters showed decreased C Reactive Protein (CRP) levels, suggestive a lower grade of inflammation in the intervention group, but this finding should be considered with caution since the values are still in the normal range. Fatigue scores improved in children with a subclinical hypothyroidism in our randomized controlled trial (RCT), after following the dietary advice for 6 months (chapter 7). Scores improved in the different fatigue domains, especially in the domains of sleep and total tiredness. The function of the thyroid, expressed by the values of TSH and FT4, was not influenced by the dietary advice. In this study, we could not find an effect of green vegetables on cognitive tiredness, probably because our control group also consumed considerable amounts of green vegetables, and the difference between the groups for this food product was less clear.
|Qualification||Doctor of Philosophy|
|Award date||18 Mar 2020|
|Place of Publication||Enschede|
|Publication status||Published - 18 Mar 2020|
- recurrent upper respiratory tract infections
- Dietary advice
- Whole dairy products