Adolescents are considered a nutritionally at-risk group, because as they transition to adulthood, they become increasingly independent and in many instances their lifestyle behaviours are adversely affected. This may include decreased physical activity, increased rates of smoking and alcohol consumption, weight gain, and poor quality diets.1,2

The International Osteoporosis Foundation states that the micronutrients of most importance to optimise bone health are calcium and vitamin D.

One of the consequences of poor-quality diets include deficiencies in micronutrients such as calcium and vitamin D. Calcium and vitamin D are extremely important for skeletal development and the attainment of peak bone mass. Serum and cellular calcium concentrations are controlled, in part, by the actions of vitamin D.3,4,5

The accrual of more than 90% of peak bone mass occurs during adolescence and by ages 25-30, the majority of new bone formation is completed.  Calcium comprises about 30% of bone mineral, and calcium deposition in bones occur at almost 300mg/day at its peak during adolescence.3,4

Reasons for low calcium intake among adolescents

Apart from the factors mentioned above, Rouf et al found that adolescents have limited knowledge of the sources of calcium, how calcium can prevent disease such as osteoporosis in later life, the recommended amounts they are supposed to consume. Some had physical barriers to consumption of calcium (eg lactose intolerance).6

A Canadian study found that adolescence and young adults consider calcium only as important for children and the elderly, while other studies show that adolescence prefer sugary drinks to milk, which is an important source of calcium.7,8

A South African study by Wrottesley et al, found that intakes of calcium, iron, zinc, vitamin A, riboflavin and niacin were below the recommended dietary allowances (RDA) in children between the ages of 10- and 13-years because of rapid urbanisation and the adoption of unhealthy diets.8

What are some of the consequences of low calcium intake during adolescence?

An adequate calcium intake throughout adolescence reduces the risk of osteoporosis in later life (see article on page 26) through greater bone acquisition during growth. Furthermore, state Harkness et al, numerous observational studies have noted an inverse association between body weight, percent body fat, and dietary calcium intake.5,9

Vitamin D receptor is expressed in all calcium-regulated tissues, including the ovary, thus, calcium and vitamin D appear to be necessary for full ovarian function.5

Furthermore, Fang et al found that higher dietary calcium intakes during adolescence is associated with faster height growth in boys. Very low intakes of dietary calcium (below 327mg/d) may result in lower adult stature. On a side-note, in men, height phobia is the most common type (3.3%–6.3%), while it ranks third for women (see article on page 40).10,11

What is the recommended calcium intake during adolescence?

Both physical activity and calcium intake show a positive impact on bone mass, according to the American National Osteoporosis Foundations. The International Osteoporosis Foundation states that the micronutrients of most importance to optimise bone health are calcium and vitamin D.12,13

Studies have shown that supplementation with calcium result in biologically, and statistically significant positive effect on bone mineral density and/or bone mineral content accrual.12

Table 1: American Institute of Medicine recommendations on dietary intake of calcium in children and adolescents14 

Age Calcium RDA (mg/day) Vitamin D RDA (µg/day)*
0-6 months 200** 10** (400IU/day)
6—12 months 260** 10 (400IU/day)
1-3 years 700 15 (600IU/day)
4-8 years 1000 15 (600IU/day)
9-13 years 1300 15 (600IU/day)
14-18 years 1300 15 (600IU/day)

*As cholecalciferol, 1µg cholecalciferol = 40IU/day under the assumption of minimal sunlight.

** Because RDAs have not been established for infants the adequate intake (AI) is shown. AI is the value that meets the needs of most children.

Conclusion

According to Patton et al, prioritising adolescent nutritional status in both females and males, as well as promoting healthy attitudes and behaviours around diet, physical activity, substance use and stress in this population, are critical to improving the intergenerational transmission of health and well-being.15

References
  1. Naude CE, et al. Vitamin D and calcium status in South African adolescents with alcohol use disorders. Nutrients, 2012.
  2. Rouf A, Nour M, Allman-Farinelli M. Improving Calcium Knowledge and Intake in Young Adults Via Social Media and Text Messages: Randomized Controlled Trial. JMIR, 2020.
  3. Christian P and Smith CP. and Adolescent Undernutrition: Global Burden, Physiology, and Nutritional Risks. Annals of Nutrition and Metabolism, 2018.
  4. Boskey AL, Coleman R. Aging and bone. J Dent Res, 2010.
  5. Harkness LS and Bonny AE. Calcium and Vitamin D Status in the Adolescent: Key Roles for Bone, Body Weight, Glucose Tolerance, and Estrogen Biosynthesis. Journal of Paediatric and Adolescent Gynaecology, 2005.
  6. Rouf A, Clayton S, Allman-Farinelli M. The barriers and enablers to achieving adequate calcium intake in young adults: a qualitative study using focus groups. J Hum Nutr Diet, 2019.
  7. Marcinow ML, et al. Young Adults’ Perceptions of Calcium Intake and Health. Health Education & Behavior, 2014.
  8. Wrottesley SV, et al. A review of adolescent nutrition in South Africa: transforming adolescent lives through nutrition initiative. South African Journal of Clinical Nutrition, 2020.
  9. Banna J, et al. Parent and household influences on calcium intake among early adolescents. BMC Public Health,
  10. Fang A, et al. Low Habitual Dietary Calcium and Linear Growth from Adolescence to Young Adulthood: results from the China Health and Nutrition Survey. Nature Scientific Reports, 2017.
  11. Altemus M, et al. Sex differences in anxiety and depression clinical perspectives. Front Neuroendocrinol, 2014.
  12. Weaver CM, et al. The National Osteoporosis Foundation’s position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations. Osteoporos Int, 2016.
  13. International Osteoporosis Foundation. Nutrition in Children. https://www.osteoporosis.foundation/health-professionals/prevention/nutrition-children-and-adolescents.
  14. Food & Nutrition Board, Institute of Medicine, National Academy of Sciences (NIH). Nutrient Recommendations: Dietary Reference Intakes (DRI) Tables. Available from: https://ods.od.nih.gov/Health_Information/Dietary_Reference_Intakes.aspx.
  15. Patton GC, et al. Adolescence and the next generation. Nature, 2018.