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Essay: Review Of Studies Into The Interaction Between Nutrition And Calcium Levels In The Human Physiology – NUT212 Title: Principles of Nutrition -Semester 1 2016

There have been numerous studies into the interaction between nutrition and calcium levels in the human physiology. The aim of this report is to review four such studies, which were conducted by: Black et al (Study 1), Vatanparast et al (Study 2), Moore et al (Study 3) and Peters et al (Study 4).

Commonalities between these four studies involved the evaluation of calcium intake through nutrition, and the consideration of a possible interaction on bone mineral density (BMD), but their research methodologies were different.

In Study 1, the objective was to measure bone health and density comparisons between prepubescent children who were long-term milk-drinking avoiders, and those children who drank milk regularly. The study recruited 50 milk drinking avoiders (30 girls, 20 boys) aged between 3 to 10 years old and compared their anthropometric bone measurements to a control group of 200 milk drinking children. The main reasons for milk avoidance were intolerance (40%), bad taste (42%) and lifestyle choices (18%). The participant data was collected via a 90-minute appointment at the Bone Research Laboratory, in which a food frequency questionnaire was given; measurements of height, weight, lean body mass, fat mass, body fat percentage and bone radius were also taken. They concluded that long-term avoidance of drinking cow’s milk is associated with poor bone health and smaller stature (1).

In Study 2, the objective was to evaluate the accumulation of total-body bone mineral content (TBBMC) through dietary consumption of milk products, vegetables and fruit in boys and girls from childhood to late adolescence. The data was collected through a 7-year longitudinal study, from 85 boys and 67 girls ranging in age from 8 to 20 years old. Anthropometric measurements and physical activity levels were collected every 6 months; dietary data was collected 2 to 4 times a year in different seasons, and annual bone scans was also collected. This study concluded that adequate intake of calcium, fruit and vegetables had a positive effect on TBBMC in boys aged 8 to 20 years old. It also deduced that the underreporting of dietary intake in girls could explain why the same results did not appear in girls (2).

Study 3, the objective of was to ascertain childhood dairy intake on later adolescent bone health. The study design for this research was a 12-year longitudinal study, following 106 children who were aged between 3 and 5 years at the beginning of the study, but only 84 had complete usable data. The data collected involved multiple sets of dietary intake diaries taken over the study period, and measurements of bone mineral content (BMC), bone area (BA) and BMD were taken in the final year of the study, when the children were between 15 and 17 years of age. This study concluded that there is evidence to suggest a positive correlation between childhood consumption and adolescent bone health (3).

Study 4,  the objective to evaluate calcium and vitamin D intake, and evaluate the impact of breakfast and dairy products on the total intake of these nutrients. There were initially 330 adolescents who had agreed to participate, but only 160 students followed through with the study; 78 males and 82 females aged between 16 to 20 years old participated, based on the study exclusion criteria. Each of the participants were given a three-day dietary record to access calcium and vitamin D intake. This study concluded that the majority of the study population did not consume the recommended quantities of calcium and vitamin D. It was also noted that breakfast was an important strategy in improving calcium and vitamin D intake.

In the discussion of these four studies, there were limitations that impacted on the results, such as under-reporting, lifestyle, sample size, and the fact that diet and physical activity were self-reported. One of the biggest limitations is the interaction between people and food. Each of the studies did not include individual physiological changes in growth from one participant to the next.

All four studies attempted to find a correlational relationship to suggest possible causation; this was more evident in Studies 1 and  4. Study 4 was the only study that included vitamin D in its research, because vitamin D promotes calcium absorption (4). These studies were an over simplification of relationships and taking into account the study’s limitations, this would render the results  fundamentally flawed.

While Studies 2 and 3 where prospective longitudinal studies; which are likely to provide with best available evidence (3), again these studies did not take into account the limitations that could have an impact within the results, such as taking into account natural growth from childhood to adolescence and under reporting of dietary intake.

To conclude, what these four studies suggest is that our body requires calcium to function properly; calcium is not just for bone health, but our heart, muscles and nerves also require this mineral (5). Studies like these are necessary in order to better understand the interaction between food and human physiology. We understand what happens when we are not given the right food to eat, because history provides evidence of what happens when society is deprived of good, healthy foods. What would be needed is a global dietary review from different nations that does not just involve the Japanese, Western or Mediterranean diet, but also includes pre-colonization Indigenous diets; a true global review.

Reference

  1. Black RE, Williams SM, Jones IE, Goulding A. Children who avoid drinking cow milk have low dietary calcium intakes and poor bone health. Am J Clin Nutr. 2002;76(3):675-80.
  2. Vatanparast H, Baxter-Jones A, Faulkner RA, Bailey DA, Whiting SJ. Positive effects of vegetable and fruit consumption and calcium intake on bone mineral accrual in boys during growth from childhood to adolescence: the University of        Saskatchewan Pediatric Bone Mineral Accrual Study. Am J Clin Nutr. 2005;82(3):700-6.
  3. Moore LL, Bradlee ML, Gao D, Singer MR. Effects of average childhood dairy intake on adolescent bone health. J Pediatr. 2008;153(5):667-73.
  4. Heaney RP. Vitamin D and calcium interactions: functional outcomes. Am J Clin Nutr. 2008;88(2):541S-4S.
  5. Nordin BE. Calcium and osteoporosis. Nutrition. 1997;13(7-8):664-86.

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