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You are what you eat, right?

This systematic review aimed to explore how some livestock-raising practices could influence human health.

Tags:
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.

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Other Articles in Issue #45 (July 2018)