Safety evaluation of vitamin A in growing dogs

Morris, Penelope J.; Salt, Carina; Raila, Jens; Brenten, Thomas; Kohn, Barbara; Schweigert, Florian J.; Zentek, Jürgen

doi:10.1017/s0007114512000128

Cited by 15 publications

(26 citation statements)

References 16 publications

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“…More recently, eight-week-old Labrador Retrievers and Miniature Schnauzers were fed one of four retinyl acetate concentrations to achieve intakes of 5.24, 13.10, 78.60, and 104.80 umol retinol (5000, 12 500, 75 000, and 100 000 IU VA/4184 kJ) (1000 kcal) ME for 1 yr [29]. There was no effect of VA concentration on any hematological or biochemical variables, bone-specific alkaline phosphatase, crossed-linked carboxyterminal telopeptides of type one collagen, and dual X-ray absorptiometry.…”

Section: Vitamin Amentioning

confidence: 99%

Meeting the Vitamin A Requirement: The Efficacy and Importance ofβ-Carotene in Animal Species

Green

Fascetti

2016

The Scientific World Journal

106

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Vitamin A is essential for life in all vertebrate animals. Vitamin A requirement can be met from dietary preformed vitamin A or provitamin A carotenoids, the most important of which is β-carotene. The metabolism of β-carotene, including its intestinal absorption, accumulation in tissues, and conversion to vitamin A, varies widely across animal species and determines the role that β-carotene plays in meeting vitamin A requirement. This review begins with a brief discussion of vitamin A, with an emphasis on species differences in metabolism. A more detailed discussion of β-carotene follows, with a focus on factors impacting bioavailability and its conversion to vitamin A. Finally, the literature on how animals utilize β-carotene is reviewed individually for several species and classes of animals. We conclude that β-carotene conversion to vitamin A is variable and dependent on a number of factors, which are important to consider in the formulation and assessment of diets. Omnivores and herbivores are more efficient at converting β-carotene to vitamin A than carnivores. Absorption and accumulation of β-carotene in tissues vary with species and are poorly understood. More comparative and mechanistic studies are required in this area to improve the understanding of β-carotene metabolism.

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Section: Vitamin Amentioning

confidence: 99%

Meeting the Vitamin A Requirement: The Efficacy and Importance ofβ-Carotene in Animal Species

Green

Fascetti

2016

The Scientific World Journal

106

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“…Data on the safety of dietary vitamin A intake at levels up to 104·80 μmol retinol (100 000 IU vitamin A)/4184 kJ (1000 kcal) have been reported previously with regard to the markers of vitamin A metabolism, haematological and biochemical variables and dual-energy X-ray absorptiometry ( 3 ) . In the present study, we evaluated the development of body weight and body composition and compared observed energy intake with predicted energy intake in response to the potential impact of dietary vitamin A intake.…”

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confidence: 98%

“…Vitamin A is an essential nutrient for dogs; however, intake of dietary vitamin A can be variable and is dependent on the natural levels of vitamin A found in some raw materials used in petfood, especially liver. Previously, it has been shown that growing as well as adult dogs can tolerate a wide range of vitamin A levels in their diet ( 1 – 3 ) due to their capacity to increase the levels of retinyl esters in serum ( 4 ) and the ability to excrete vitamin A as both retinol and retinyl esters in the urine ( 3 , 5 – 7 ) . The impact of vitamin A and its metabolic product retinoic acid on energy metabolism in dogs is not clear, although data from rodents indicate an influence of retinoic acid on both thermogenesis and lipid synthesis via its actions when bound to the retinoic acid receptor ( 7 , 8 ) .…”

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confidence: 99%

Energy intake, growth rate and body composition of young Labrador Retrievers and Miniature Schnauzers fed different dietary levels of vitamin A

Brenten¹,

Morris²,

Salt³

et al. 2014

Br J Nutr

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Research in rodents has shown that dietary vitamin A reduces body fat by enhancing fat mobilisation and energy utilisation; however, their effects in growing dogs remain unclear. In the present study, we evaluated the development of body weight and body composition and compared observed energy intake with predicted energy intake in forty-nine puppies from two breeds (twenty-four Labrador Retriever (LAB) and twenty-five Miniature Schnauzer (MS)). A total of four different diets with increasing vitamin A content between 5·24 and 104·80 mmol retinol (5000-100 000 IU vitamin A)/4184 kJ (1000 kcal) metabolisable energy were fed from the age of 8 weeks up to 52 (MS) and 78 weeks (LAB). The daily energy intake was recorded throughout the experimental period. The body condition score was evaluated weekly using a seven-category system, and food allowances were adjusted to maintain optimal body condition. Body composition was assessed at the age of 26 and 52 weeks for both breeds and at the age of 78 weeks for the LAB breed only using dual-energy X-ray absorptiometry. The growth curves of the dogs followed a breed-specific pattern. However, data on energy intake showed considerable variability between the two breeds as well as when compared with predicted energy intake. In conclusion, the data show that energy intakes of puppies particularly during early growth are highly variable; however, the growth pattern and body composition of the LAB and MS breeds are not affected by the intake of vitamin A at levels up to 104·80 mmol retinol (100 000 IU vitamin A)/4184 kJ (1000 kcal).

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“…Moreover, the rice bran diet presented greater palatability compared to the defatted rice bran diet. Vitamin A (retinol), whose safe upper limit in complete diets for dogs ranges from 5.24 to 104.80 mmol, is an essential fat-soluble vitamin at the center of investigations in dogs in the context of immune stimulation, vision-supporting functions, reproduction, bone growth, and cellular differentiation [88][89][90]. In dogs, unlike humans where retinyl esters are only detected in plasma in cases of intoxication or following a vitamin A-rich meal [91], vitamin A is present in the plasma predominantly in the form of retinyl esters, in both adequate and vitamin A-deprived states [92].…”

Section: The "Market Stand" Of Functional Pet Foodsmentioning

confidence: 99%