Saturday, 19 December 2015

The bones of the matter - Blog 5

We have all heard of the French Paradox – How do french women stay so impossibly slim on a diet based on wine, cheese and butter? Have you heard about the Asian paradox?  Given the connection between dairy products,  calcium intake, bone density and hip fractures, how is it that Asians,  who have low dairy and low calcium diets,  have such a low risk of hip fracture (Anderson & Sjöberg, 2001).

In a population, hip fractures are easier to measure than bone density consequently there is more data on it. You need to fall (or have impact) and have low bone density to fracture your hip. Factors like exercise (and presumably alcohol consumption) affect how much falling goes on. The serious news: Hip fractures are to be avoided if you are over 65 as it significantly increases your chance of dying  in the following year (Walsh, 2011).

Bones do need calcium, along with phosphorus (eggs are a good source) and Vitamin D (Oily fish)(Harvard Medical School, 20013). Dairy products supply up to ¾ of our dietary calcium. For women in my age group it is virtually impossible to get the recommended daily  allowance  (now known as the DRI) of 1000 - 1300 mg (depends on who you ask) without dairy -  1 cup milk has 400mg, of yoghurt 300mg while 1 cup of broccoli  has 60mg,  10 almonds, 30mg (NZ Nutrition Foundation, 2014). Could Asians be getting away with a calcium intake way below the DRI because it’s not the only thing going on (Harvard Medical School, 20013).

There is definitely something questionable about the recommendations which soar for older women  (NZ Nutrition Foundation, 2014). Bone density does decrease with age and there is a link between intakes <400mg per day and fractures (Warensjö et al., 2011). However it looks doubtful that higher (1000- 1300mg) calcium intake is the right approach. In fact exercise seems to be the strongest influence on reducing hip fracture (Kannus, 1999).

While it is indisputable that  the Kneebone’s connected to the thigh bone and the thigh bone’s connected to the hip bone, the hip bone’s connection to our leading national industry does cry out (like a bobby calf, separated from its mother) for more research.

In my next blog: How, according to Fonterra, milk can make you more muscular and attractive to the opposite sex (when taken in conjunction with an active lifestyle).

References:
Anderson, J. J. B., & Sjöberg, H. E. (2001). Dietary calcium and bone health in the elderly: uncertainties about recommendations. Nutritional Research, 21(1-2), 263-268.
Harvard Medical School. (20013). What you need to know about Calcium. Retrieved from http://www.health.harvard.edu/staying-healthy/what_you_need_to_know_about_calcium
Kannus, P. (1999). Preventing osteoporosis, falls, and fractures among elderly people. The British Medical Journal, 318(7178), 205-2016.
NZ Nutrition Foundation. (2014). Calcium. Retrieved from http://www.nutritionfoundation.org.nz/nutrition-facts/minerals/calcium
Walsh, N. (2011). Mortality High in Year After Hip Fracture. Retrieved from http://www.medpagetoday.com/Orthopedics/Orthopedics/28742
Warensjö, E., Byberg, L., Melhus, H., Gedeborg, R., Mallmin, H., Wolk, A., & Michaëlsson, K. (2011). Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study. Retrieved from http://www.bmj.com/content/342/bmj.d1473.abstract


3 comments:

Christina Victoria said...

An interesting paradox indeed. It makes sense that Asian women consume little calcium since they have a high rate of lactose intolerance, and that elderly Asian women have just as high a vertebral fracture occurrence rate as Caucasian women do (http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Background/asian_american_women.asp), but it's puzzling that their hip fracture rate is significantly lower. There is some evidence that longer hip axis length contributes to a higher risk of hip fracture, and Asian women generally have shorter hip axis lengths than their Caucasian counterparts, even after height adjustment. There are also some physiological mechanism differences between the races that could contribute to the lower fracture rate among Asians despite lower overall bone mineral density (see the 'Do Risk Factors for Fracture Differ by Ethnicity and Race?' section in http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111798/). But the data is fairly limited; I agree with you that more research is required.

Regardless of age, I think basic resistance/strength training (not just cardiovascular exercise on its own) coupled with good calcium consumption is your best defense against fractures, and there's evidence supporting this (http://www.cdc.gov/physicalactivity/growingstronger/why/index.html). For example, I know a young fit girl about my age that was not calcium deficient in the least, yet had recurrent, inexplicable fractures in her wrist, hip, toes etc that occurred spontaneously as she was doing athletic training over the past two years. The problem only went away when she started doing additional strength training on top of her sports training. Of course, the type of strength training recommended for an older adult will be a bit different to what's appropriate for a younger person.

Jindina Locke said...

Very interesting. I hadn't considered that before, but yes, it does weaken the argument that calcium is the key to less fractures. I believe strength training is definitely an integral part to the equation. Perhaps exercises such as Tai Chi, which are performed regularly in Asian countries and improve balance, maybe reduce the incidence of falling, and therefore the incidence of fractured hips. Christina makes a good point about the shorter hip axis lengths, surely this increases their strength to some degree. It would be interesting to see a study done on this.

Cherie Grey said...

Its a very interesting topic seeing as I have now hit the danger zone apparently.