Dairy and calcium

In the Western world it is nigh on impossible to avoid dairy. It appears to be the basic ingredient in most beverages and food products from the obvious breakfast lattes to lunchtime cheese sandwiches and post dinner dessert yogurts. Even unsuspected food offerings like Doritos® Cool Ranch® flavoured crisps and Kellogg’s® Special K® cereal Bars contain some form of dairy. It seems that our appetite for dairy as a source of calcium is insatiable.
Dairy
The role of calcium
Calcium is a necessary micronutrient, which promotes good bone health and prevents tooth decay. It is furthermore implicated in muscle function and blood clotting regulation (coagulation). The obvious symptoms of calcium deficiency include rickets in children and osteoporosis, commonly known as brittle bone disease, in adults. Your genetic make-up plays an integral part in your later life bone mass density. However, other factors that affect your ability to achieve maximum bone density include nutrition (calcium and protein intake), physical activity, endocrine status and exposure to risk factors, which include nicotine exposure and excessive alcohol intake. We furthermore understand that levels of vitamin D are tightly linked with the absorption of calcium as adequate vitamin D status is a prerequisite for calcium absorption (Caroli et al. 2011). Vitamin D rich foods include oily fish (mackerel and wild salmon), butter and fortified foods. In many households oily fish seem to be noticeably absent from the menu as most people do not like either the smell or taste, or may follow a vegetarian or vegan diet. Sun exposure can contribute significantly to vitamin D levels and many a UK resident lament annually to the wet summers where adequate sun exposure is severely limited unless you have the opportunity to travel abroad to sunnier climates and spend time outdoors.

Dietary sources of calcium
The NHS choices website list dairy along with a host of other food options as optimum calcium choices, which furthermore include green leafy vegetables, soya products, nuts and fish such as sardines. It is interesting to note that apart from dairy sources, fortified cereals are a major source of calcium in most Western diets due to mandatory fortification (Theobald, 2005).

When making dietary choices it may be useful to note the actual calcium content of our desired meals. In the table below you can see that even though dairy is considered an optimal source of calcium, not all dairy products contain the same amount of calcium when compared gram for gram. There are also a few surprising products listed that may not seem to be an obvious source of calcium.

Calcium in food (per 100 g portion):
Parmesan 1025 mg
Cottage cheese (plain reduced fat) 13 mg
Whole milk 118 mg
Semi-skimmed milk 156 mg
Yogurt (low fat, plain) 162 mg

Wheat flour (white, self-raising) 350 mg
Frosties 453 mg
Gingernut biscuits 130 mg

Curly kale (boiled) 150 mg
Watercress (raw) 170 mg
Figs (dried) 250 mg

Tofu (steamed) 510 mg
Almonds 240 mg
Sesame seeds 670 mg

Sardines (in brine, drained) 540 mg
Whitebait (in flour, drained) 860 mg
Burger (grilled) 110 mg
(Theobald, 2005)

At what stage in life is calcium intake most beneficial?
Most people recognize the importance of dietary calcium in relation to the development of osteoporosis and hence the national and international drive to entice people to consume diary products. A study in rural Swietokrzyskie, Poland, examined 172 women and concluded that even though none of the participants consumed sufficient dietary calcium (the median was approximately 400 mg/day), bone mineral density was not related to current intake but highly dependent on dairy consumption in childhood (Sobas, K, et.al 2010). Therefore it is postulated that calcium intake from birth to puberty is more predictive of higher bone mineral density in later years than intake during those more at risk age, such as post menopausal women who are routinely made aware of the potential risk. Numerous studies have shown that the development of osteoporosis is more dependent on low physical activity, inadequate sun exposure, hormonal disorders, certain pharmacological agents, chronic disease, and a history of fractures in the past than dietary intake of calcium beyond a certain age. However that does not mean that you can omit calcium rich food from your diet especially later on in life. The intake of calcium rich food has been shown to have a protective effect on colorectal cancer. Calcium intake is also associated with a reduction in cardiovascular disease risk and has been linked with positive weight management.

What are the UK guidelines?
The recommended daily intake of calcium for British adults is 700 milligrams (Department of Health, 1999). The intake of calcium has increased over the last 30 years and figures show the average daily intake of UK men is 1007 mg and for women it is 777 mg (Henderson et al, 2002). However it appears that a large proportion of teenage boys and girls are inadequately consuming dietary calcium. This is hardly surprising as most adolescents may not choose oily fish, leafy greens, or nuts and seeds as part of their regular diet. Even though dairy intake appears to be frequent with regular intake of milky coffee drinks and yogurt, it may still be insufficient to safeguard against calcium related illness later on in life, especially when other factors such as lifestyle choices are considered.

Dietary intake of calcium has been shown to have many health benefits, protecting against osteoporosis, certain cancers, heart disease and even aiding weight management. Dairy always seem to top the list for calcium rich food which may be fuelled by the population’s insatiable need for milk, cheese, yogurt and chocolate products. Most people do not know that there are other dietary sources of calcium, which include leafy green vegetables, nuts, seeds, and oily fish. These sources of calcium are however the most notably absent ingredients from many households in modern society even though they each have other important health benefits that one source alone, including dairy, does not provide. If dairy sources of calcium are to be believed to be superior then perhaps all that is needed is the consumption of a cheeseburger and a large milkshake to prevent a host of calcium related illnesses in the long run*.

* May contain traces of irony

References
Caroli A, Poli A, Ricotta D, Banfi G, Cocchi D (2011) Invited review: Dairy intake and bone health: A viewpoint from the state of the art. Journal of Dairy Science, Vol. 94, pp. 5249-5262

Department of Health (1999). Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Tenth impression, London, The Stationery Office

Henderson L, Gregory J, Swan G (2002) The National Diet and Nutrition Survey: Adults Aged 19-64 Years Types and Quantities of Food Consumed. Volume 1, The Stationery Office, London

Sobas, K, et.al (2010) Analysis of the occurrence of dietary and non-dietary factors of fracture risk in relation to bone mineral density in women. Acte Sci. Pol. Techno. Aliment., Vol. 9(3), pp. 373-382.

Theobald, HE (2005) Dietary calcium and health. British Nutrition Foundation, London, UK, pp. 237-277

http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Calcium.aspx accessed 2/4/2013

This article was published in issue 208 of Positive Health On-Line Magazine in August 2013

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