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Study under review: Meat, eggs, full-fat dairy, and nutritional boogeymen: Does the way in which animals are raised affect health differently in humans?
Introduction
Cancer prevention recommendations vary significantly[1] from different organizations regarding macronutrient composition and food type. Most of these recommendations are based on epidemiologic studies[2] that vary in population, data evaluation, and dietary assessment methods, and have some inherent biases. Advice to consume a low-fat diet and increase fruit and vegetable intake has yielded inconsistent results[3], with the postulation that there may be a low threshold effect (i.e., benefits are only seen in populations consuming little fruits and vegetables to begin with) or specific nutrients that have benefits.
It appears consumers believe[4] organic food reduces cancer risk, but whether or not this is actually true or not is still being explored. One possible culprit could be depleted nutrients in non-organic crops. From 1950 to 1999, various garden crops are reported to have decreased levels of some nutrients[5], conventionally believed to be because of agricultural conditions and/or practice, but the cause is actually suggested to be the selection of cultivars that increase yield. It has also been suggested that soil mineral depletion[6] has not influenced mineral content of fruits and vegetables, with the only contributor to a ‘dilution effect’ being the adoption of higher yield crop varieties.
The latest buzz on animal foods and cancer risk has to do with some strong evidence that processed and red meat increases cancer risk[7], according to the World Cancer Research Fund. What if the conditions that animals are raised in have an impact on the relationship of animal foods with cancer risk? One review[8] has reported that organically raised animals produce meat and cheese with higher conjugated linoleic acid (CLA), and polyunsaturated fatty acids, such as the now famous omega-3 fatty acids. Another study[9] has suggested that meat from pasture-fed animals contain more healthful nutrients than grain-fed animals, such as fatty acids and antioxidants, which are associated with cancer risk prevention. The specifics of some of these differences are shown in Figure 1.

CLA[10] and omega-3[11] have been associated with various health benefits, and the increased levels of both that are found in products from animals raised in more species-appropriate conditions suggests the raising of animals could impact human health and cancer prevention. The authors of the study under review state that they wanted to address the lack of scientific dialogue regarding differences that pasture-raised animal foods may have on health and cancer prevention. This study aimed to assess the differing effects on CLA and omega-3 and other health biomarkers in humans following the consumption of eggs, butter, cheese, and meat from differently raised animals.
Cancer prevention recommendations vary significantly across organizations, whether it be macronutrient composition or food type, but the public seems to believe that the conditions in which the food is grown have an impact on its cancer-preventive potential. It appears that agricultural conditions and practices are not to blame for the reduced nutrient levels of plants, while animals raised alternatively to conventional methods appear to yield animal products with higher nutritive value, such as increased conjugated linoleic acid (CLA) and omega-3 fatty acid. The study under review aimed to assess differences in CLA, omega-3, and other health biomarkers in humans following the consumption of animal products from animals raised through different methods.
Who and what was studied?
What were the findings?
What does the study really tell us?
The big picture
Frequently asked questions
What should I know?
Other Articles in Issue #45 (July 2018)
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Mini: The International Olympic Committee’s take on what supplements actually work
The IOC released a consensus statement earlier this year chock full of information on dietary supplements. Here, we summarize what they said about which supplements have the best evidence base for athletes.
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Mini: The latest skinny on polyunsaturated fats according to the Cochrane Collaboration
Want a very abbreviated summary of a series of recent meta-analyses examining PUFAs’ effects on cardiovascular health? We got you covered.
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Can vitamin D supplementation during pregnancy improve offspring health?
Vitamin D levels in expecting moms tend to be low worldwide. Supplementing with lower doses of vitamin D while pregnant seems to improve some aspects of their children’s health.
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Is timing really everything?
Casein looks like a good candidate for a protein source that slowly releases amino acids into the body to help with overnight muscle building. But does it actually do any more if taken at night?
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The ketogenic diet — there’s an app for that!
How much of an impact can intensive support combined with a ketogenic diet make on CVD risk markers and glycemic control in people with type 2 diabetes?
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Aspartame: It’s sweet to eat, but is it a trick or a treat?
While you shouldn’t eat it by the bowl, it hardly affects glycemic control
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Does the 16:8 fasting diet boost weight loss and health?
This pilot study examined how restricting feeding to eight hours a day every day affects the weight and metabolic health of people with obesity