Sedentary behaviour and health in children: Evaluating the evidence

There is much to do about sedentary behaviour -too much (prolonged) sitting, for example by means of TV watching, computer and other IT activities, long school or office days et cetera- as a possible risk factor for cardiometabolic health. Scientists have claimed that sedentary time is a risk factor for cardiometabolic health partly or largely independent of physical activity. I.e. even if you do enough exercise, if you sit most of the rest of the day, your cardiometablic health may be at unnecessary risk. Some countries have already proposed recommendations for maximum sedentary time and interventions to reduce or interrupt sedentary time have been developed and are being tested or implemented.
In a commentary just published in the journal Preventive Medicine, with Prof. Mai Chin A Paw as first author, we argue that the evidence for sedentary behaviour as an independent cardiometabolic risk factor for children and adolescents is certainly not yet convincing, and propose research that should be conducted first to see if a stronger case can be build for treating sedentary behaviour as a separate risk factor, before we start using the meagre means for preventative interventions on sedentary behaviour instead of promoting physical activity and healthy eating.

Personal, home- and friend-related factors regarding diet, physical activity and sedentary behaviours among schoolchildren in Europe

To design interventions that target energy balance-related behaviours -i.e. diet, physical activities (PA) and sedentary behaviours- among school-age children, knowledge the possible determinants of these behaviours is needed. In a study just published in PLOS ONE -with Dr. Saskia te Velde as first author- we investigated schoolchildren's  personal beliefs and attitudes, home- and friend-related variables regarding soft drink intake, fruit juice intake, breakfast consumption, TV viewing and physical activity in eight countries across Europe. This study was part of the ENERGY project.
A majority of the children reported unfavourable attitudes, preferences and subjective norms regarding soft drink, fruit juice intake and TV viewing accompanied with high availability and accessibility at home. Few children reported unfavourable attitudes and preferences regarding breakfast consumption and PA. Many children reported unfavourable health beliefs regarding breakfast consumption and TV viewing. Substantial differences between countries were observed, especially for variables regarding soft drink intake, breakfast consumption and TV viewing.
We concluded that children across Europe have favourable attitudes to some healthy behaviours (PA, breakfast intake) as well as to some unhealthy behaviours (soft drink consumption, TV viewing). Additionally, many children across Europe have personal beliefs and are exposed to social environments that are not supportive to engagement in healthy behaviours. Moreover, the large differences in personal, family and friend-related variables across Europe argue for implementing different intervention strategies in the different European countries.

Patterns in sedentary behaviour: data reduction issues

Sedentary behaviour may be another risk factor for obesity and cardiometabolic risk. Sedentary lipoprotein lipase activity, leading to a prolonged time in which cellular metabolism substrates are present in the vascular compartments.
behaviour is not the same as the opposite of lack of physical exercise: even people who have enough exercise may sit too much during the rest of the day. Recent evidence suggest that it may be prolonged, uninterrupted sitting -rather than total sitting time- that may increase cardiometabolic risk. Prolonged sitting leads to the loss of contractile stimulation in weight-bearing muscles, which suppresses skeletal muscle
However, measuring sitting time and sedentary patterns is not as straightforward as it may seem. Sedentary behaviour is maybe best measured with accelerometers, however, no consensus is yet established on such accelerometer data most validly reflect sedentary time or sedentary patterns.
In a study just published in PLOS ONE -with Prof. Mai Chin A Paw as first author- we aimed to establish evidence-based accelerometer data reduction criteria to accurately assess total sedentary time and sedentary patterns in children. More than 1000 children in five countries in Europe wore accelerometersfor at least 6 consecutive days. We explored 1) non-wear time criteria; 2) minimum daily valid wear time; 3) differences between weekday and weekend day; and 4) minimum number of days of accelerometer wear by comparing the effects of commonly used data reduction decisions on total sedentary time, and duration and number of prolonged sedentary bouts.
More than 60 consecutive minutes of zero counts was the optimal criterion for non-wear time. Increasing the definition of a valid day from 8 to 10 hours wear time hardly influenced the sedentary outcomes, while the sample size of children with more than 4 valid days increased from 69 to 81%. On weekdays, children had on average 1 hour more wear time, 50 minutes more total sedentary time, 26 minutes more sedentary time accumulated in bouts, and 1 more sedentary bout. At least 6 days of accelerometer data were needed to accurately represent weekly sedentary time and patterns.

No main effect of daily vitamin B-12 and folic acid supplementation on fracture incidence in elderly

Elevated plasma homocysteine concentrations are a risk factor for osteoporotic fractures. Lowering homocysteine with combined vitamin B-12 and folic acid supplementation may reduce fracture risk.
In a paper that just appeared in pre-publication in the American Journal of Clinical Nutrition -with Janneke van Wijngaarden and Karin Swart as the main authors- the methods and results of the B-vitamins for the PRevention Of Osteoporotic Fractures (B-PROOF)] study are presented. The rationale and full description of the design of this study was published in an earlier paper in BMC Geriatrics. This study aimed to determine whether vitamin B-12 and folic acid supplementation reduces osteoporotic fracture incidence in hyperhomocysteinemic elderly individuals.
This was a double-blind, randomized, placebo-controlled trial in 2919 participants aged ≥65 y with elevated homocysteine concentrations. Participants were assigned to receive daily 500 μg vitamin B-12 plus 400 μg folic acid or placebo supplementation for 2 y. Both intervention and placebo tablets
also contained 600 IU vitamin D3.
Osteoporotic fractures occurred in 61 persons (4.2%) in the intervention group and 75 persons (5.1%) in the placebo group. Osteoporotic fracture risk was not significantly different between groups. For persons >80 y, osteoporotic fracture risk appeared to be somewhat lower in the intervention group than in the placebo group. The total number of adverse events (including mortality) did not differ between groups. However, 63 and 42 participants in the intervention and placebo groups, respectively, reported incident cancer.
These data show that combined vitamin B-12 and folic acid supplementation had no effect on osteoporotic fracture incidence in this elderly population. Exploratory subgroup analyses suggest a beneficial effect on osteoporotic fracture prevention in the very old. However, supplement use was also associated with increased incidence of cancer, although the study was not designed for assessing cancer outcomes. Therefore, vitamin B-12 plus folic acid supplementation cannot be recommended at present for fracture prevention in elderly people.

Health related quality of life and survival in patients with head and neck cancer: A systematic review

In a study just published in the journal Oral Oncology -with Annette van Nieuwenhuizen as first author- we systematically reviewed the available scientific evidence on the association between health-related quality of life and survival in patients with head and neck cancer.
Nineteen studies were included in the review. We found strong evidence for a positive association between pre-treatment physical functioning and survival and between change in global quality of life from pre-treatment to 6 months after treatment and survival. I.e. patients with better physical functioning before treatment and with more positive or less negative changes in global quality of life had better survival.

The school nutrition environment in 7 countries in Europe

The school is an important setting for promoting healthy eating especially at the transition from childhood to adolescence. In a study just published in e-pub in the journal Health and Place, with Prof. Nanna Lien as first author, we explored differences in school nutrition environment factors in elementary schools across seven countries in Europe. A secondary aim was to explore whether any of these school nutrition environment factors were associated with soft drink consumption of young adolescents.  With questionnaires administered by school staff and management and by audits -i.e. direct systematic observations of the school food environment by our researchers- the school food environment was assessed. We looked at such issues as availability and accessibility of foods, rules and regulations regarding food and eating, and role modelling and actual teaching regarding healthy eating by school staff. A large variety of food policy and practices influencing the school food and nutrition environment were found within and between countries across Europe. However, only very few significant association with  the pupils׳ soft drink consumption were found.

Do children and parents agree on parenting practices regarding dietary, physical activity and sedentary behaviours?

Parents and their parenting practices play an important role in shaping their children's dietary and physical activity behaviours and the home environment where these behaviours develop and take place. Measurement of such parenting practices can be based on parent- or child reports, but parents and children may not necessarily agree on how they experience and report such parenting practices. In a study just published in pre-pub in the journal BMC Public Health we aimed to assess agreement between parent and child reports on parental practices regarding such lifestyle behaviours that contribute to energy balance, and risk for overweight and obesity.
We used the data from the ENERGY-project, in which a cross-sectional survey was conducted among 10-12 year old children and their parents in eight European countries. Both children and parents filled in a questionnaire on 14 parental practices regarding five different behaviours (i.e. soft drink, fruit juice and breakfast consumption, sports activity and watching TV) and socio-demographic characteristics. Children's weight, height, and waist circumference were measured at school. We calculated percentages of agreement between children and their parents and kappa statistics per practice and country and assessed factors associated with agreement using multilevel linear regression. Reports of 6425 children and their parents were available for analysis. Overall mean agreement between parent and child reports was 43% and varied little among countries. The lowest agreement was found for questions assessing joint parent-child activities, such as sports or watching TV, and for parental allowance of the child to have soft drinks, or to watch TV. In general, agreement was lower for boys, younger children, younger parents, parents with less than 14 years of education, single parents, and parents who had higher BMI's.
Parents and children thus perceive parental practices regarding dietary, physical activity and sedentary behaviours differently in all parts of Europe, with considerable variation across specific practices and countries.