Domestic cats convert [²H₈]‐β‐carotene to [²H₄]‐retinol following a single oral dose

Abstract

Many animals convert β-carotene to retinol to meet their vitamin A (VA) requirement. However, this pathway is inefficient in many carnivores. This study quantified the plasma response to a single oral dose of [(2) H(8)]-β-carotene in adult domestic cats, including measurement of [(2) H(4)]-retinol derived from the dose. Cats were fed with either a control diet containing adequate VA (n = 5) or a VA-devoid diet (n = 5) for 28 days. An oral dose of either 5 mg/kg body weight (BW) (n = 4) or 10 mg/kg BW (n = 6) of [(2) H(8) ]-β-carotene was administered on day 28. Plasma samples were collected prior to dosing and at 6, 12, 24, 32, 48, 72, 120, 168 and 216 h post-dose. Plasma retinoids and β-carotene were measured using HPLC and [(2) H(4)]-retinol by GC-ECNCI-MS (gas chromatography/electron capture negative chemical ionization/mass spectrometry). β-carotene was undetectable in plasma prior to dosing. Post-dose, mean peak plasma β-carotene was 0.37 ± 0.06 nmol/ml at 9.0 ± 1.8 h following the dose, while [(2) H(4) ]-retinol peaked at 3.71 ± 0.69 pmol/ml at 55.2 ± 16.3 h. The ratio per cent of total area under the curve for [(2) H(4)]-retinol compared with the β-carotene response was 4.6 ± 2.6%. There was little effect of diet or dose on the β-carotene or [(2) H(4)]-retinol responses. The appearance of [(2) H(4)]-retinol in plasma indicates that cats are capable of converting β-carotene to active VA. Conversion efficiency was not calculated in this study, but it is likely inadequate to meet cats' VA requirement without the inclusion of preformed VA in the diet.

A cross-sectional study of owner-reported health in Canadian and American cats fed meat- and plant-based diets

“…The proportion of respondents keeping cat(s) only (653/1325 49%) did not differ from those keeping dog(s) and cat(s) (672/1325, 51%). The median number of cats kept per respondent was two (range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Most cats were acquired from shelters, rescues or veterinarians (664/1241, 54%), followed by tamed stray, feral or found cats (214/1241, 17%) or inherited or gifted from friends and family (167/1241, 13%).…”

“…As a consequence, cats have unique nutritional adaptations resulting in particular dietary requirements [3,4]. Briefly, in comparison to their omnivorous counterpart, the domestic dog, the cat's requirement for total protein is higher, and they require dietary provision of taurine, long-chain polyunsaturated fatty acids and vitamin A [1,[5][6][7][8]. Protein content and quality, in terms of amino acid digestibility, bioavailability and balance, is typically higher in animal-derived as opposed to plant-derived ingredients [9].…”

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

“…Many of these early studies were conducted before the advent of HPLC methods for analysis of retinoids and carotenoids so they suffered from a lack of sensitivity and specificity of analytical methods. Data from our laboratory indicates that cats do have the ability to convert BC to VA, though the conversion efficiency is very low [186]. Regardless, it is clear from the earlier depletion studies that BC cannot replace VA in the diets of cats.…”

“…However, more recent studies and our own experiments have found absorption of BC supplements into plasma to be quite substantial in cats, though these studies use relatively high doses [177, 186, 187]. Domestic cats consuming commercial diets seem to have very low to no circulating BC [18, 187].…”

Plant Kingdom as Source of Vitamins

“…Noteworthy, not all animal species are able to convert provitaminic carotenoids: in most carnivorous species, this pathway is inefficient or insufficient (Green et al 2011).…”