Consumers can meet intake requirements for nutrients such as calcium via non-dairy sources, but these are not a ‘nutritionally significant equivalent’ for dairy foods, according to a new US study.
Writing in the November issue of the journal Nutrition Research, Fulgoni et al. (whose study was co-founded by the National Dairy Council and Dairy Research Institute), concluded that consumption of calcium-equivalent amounts of some non-dairy foods was unrealistic.
2010 US Dietary Guidelines recommend that Americans aged 9 years or older consume 3 cups of low-fat or fat-free milk or milk products daily; children aged 4-8 years are recommended to consume 2.5 cups to meet dietary needs for nutrients such as calcium.
But the scientists said that US citizens only consumed, on average, 1.8 cups of milk or milk products daily, with few consuming the recommended three servings.
Fulgoni et al. wrote: “Many Americans consequently fall short of achieving the recommended intakes for many nutrients provided by dairy products, including calcium, vitamin D and potassium.”
Citing links between milk and milk product consumption and health outcomes such as improved bone health, the scientists noted “many essential nutrients” within dairy foods, which they said contributed about 70 per cent of calcium, for instance, to the diet.
The study profiled various diets based on energy content, to assess the nutritional impact of removing or adding an 8oz (226g) dairy serving, completely removing dairy from diets or using ‘dairy replacement’ foods such as calcium, vitamin-fortified soy drinks and leafy greens.
“The dairy food group (milk, cheese and yogurt), contributes substantial amounts of many essential nutrients to the diet, including protein, vitamins A,D and B12, riboflavin, and minerals calcium, potassium, phosphorus, magnesium and zinc,” Fulgoni et al. wrote.
The scientists concluded that replacing all dairy servings in a diet with calcium-equivalent servings of replacement foods, “may provide the same amount of calcium, but will not equivalently replace other nutrients including magnesium, phosphorus, potassium or protein”.
Fulgoni et al. added that removing a dairy serving or completely eliminating dairy foods from the US diet would have “significant consequences for some already inadequate nutrient intakes”.
“Non-dairy calcium replacement foods would not fill those nutrient gaps,” according to the authors.
Non-dairy calcium sources
The team also assessed US National Health and Nutriton Examination Survey (NHANES) data, which collated nutrient intake data for 16,822 individuals aged over 2 years who completed food surveys between 2003 and 2006.
This data showed that US dairy consumption was mainly white milk, mixtures containing dairy products and cheese. Non-dairy calcium alternatives in use included fortified orange juice, non-fat fortified soy beverage, leafy greens and boy fish.
“[But] for many Americans, these foods are rarely consumed, thus, even these amounts would reflect a significant shift in usual diet patterns,” Fulgoni et al. said.
“Compared with non-dairy calcium food sources, consumption-weighted data shows that dairy products have a significantly greater concentration for many of the nutrients assessed (except for vitamin A, niacin, potassium and magnesium,” they added.
Discussing study weaknesses, the authors cited the assumption that the dietary nutritional adequacy of nutritional profiles was based on the assumption that calcium from non-dairy sources was equivalent to cow’s milk in bioavailability terms.
They wrote:“In reality, fortification techniques (e.g. for soy beverages) and naturally present compounds in some foods (eg. oxalate in some green leafy vegetables) can significantly affect nutrient bioavailability.”
Title: ‘Nutrients from dairy foods are difficult to replace in diets of Americans: food pattern modeling and an analysis of the National Health and Nutrition Examination Survey 2003-2006’
Authors: V.Fulgoni, D.R Keast, N.Auestad, E.E Quann
Source: Nutrition Research 31 (2011) pp.759-765, doi:10.1016/j.nutres.2011.09.017