Effects of Age and Dietary β-Carotene on Immunological Variables in Dogs

Abstract

beta-Carotene is a naturally occurring carotenoid reported to have health-promoting effects in several species. Advancing age is known to have a negative impact on various immune variables in several species. This study was conducted in order to assess the effect of age on immune response in dogs and to determine whether beta-carotene is able to reverse this age-associated decline. To test this hypothesis, young and old dogs (n = 36) were fed either a control diet or experimental diets containing supplemental beta-carotene for 2-month periods. Age significantly (P < .05) lowered CD4+ T cell populations (47.2% versus 33.7%; young-control versus old-control, respectively) and beta-carotene restored percent distributions in old dogs to nonsignificance versus younger controls (41.0%). T cell proliferation was lower in old dogs (30,254 +/- 2,248 versus 14,811 +/- 2,497 cCPM; young-control versus old-control, respectively; P < .05), and beta-carotene supplementation significantly improved responses in this age group (21,329 +/- 2,275 cCPM). Although B cell proliferation was depressed with age (17,967 +/- 1,384 versus 7,535 +/- 1,469 cCPM; young-control versus old-control, respectively; P < .05), beta-carotene supplementation improved B cell proliferation in young dogs (23,500 +/- 1,339 cCPM). Old dogs displayed lower delayed-type hypersensitivity test (DTH) responses versus younger controls to both phytohemagglutinin-P (PHA; 11.1 +/- 0.95 versus 7.57 +/- 1.15 mm; young-control versus old-control, respectively; P < .05) and sheep red blood cell (RBC; 9.12 +/- 0.62 versus 8.08 +/- 0.75 mm; young-control versus old-control, respectively; P< .10). beta-Carotene improved these responses, mostly within the first 24-48 hours after injection. In summary, older dogs have lower immunological responses compared with younger controls. beta-Carotene supplementation significantly restored immune responses in older dogs when compared with their age-matched controls and younger counterparts.

Astaxanthin modulates age-associated mitochondrial dysfunction in healthy dogs1

“…Astaxanthin partially restored immunosenescence, an age-associated decline in immune function (Grubeck-Loebenstein, 1997), by increasing antibody production in humans (Jyonouchi et al, 1995). Dietary b-carotene prevented an age-related decline in immune health in dogs (Massimino et al, 2003). In fact, b-carotene improved certain cell-mediated immune response in geriatric dogs to levels observed in young dogs.…”

Nutritional management and disease prevention in healthy dogs and cats

“…The implication is that such enhancement will extend, or reverse the aging process and prevent or reduce the likelihood of disease. Documented alterations in immune and antioxidant parameters in dogs and cats (Hayek et al, 2000;Kearns et al, 2000;Massimino et al, 2003) as well as clinical improvement in cognitive function in dogs through supplementation has been reported (Head, 2007). Existing studies do not address the possible preventive or long-term effects of these supplements and diets, and if animals consuming them will live longer or have a lower incidence of disease.…”

Roles of plant‐based ingredients and phytonutrients in canine nutrition and health

“…Consequently, both β‐carotene and lutein have demonstrated the ability to enhance cell‐mediated and humoral immune response in female Beagle dogs (Chew, Park, Weng, et al, 2000; Chew, Park, Wong, et al, 2000; Kim et al, 2000). Additionally, a study in a group of older dogs (mean age 10.6 years) demonstrates that supplementation with β‐carotene at 17.9 mg/kg diet improved immunological variables by increasing levels of CD4+ T cells, improving T‐cell proliferation and heightening DTH responses (Massimino et al, 2003). The long‐term clinical effects of these immunological shifts remain unknown.…”

“…• Dogs provided βcarotene showed higher CD4+ T-cell levels and displayed increased delayed-type hypersensitivity (DTH) response to both specific and non-specific immune response triggers . • In older dogs supplemented with βcarotene, immunological variables were altered by increasing levels of CD4+ T cells, improving T-cell proliferation, and heightening DTH responses (Massimino et al, 2003). • Yellow-orange vegetables and green leafy vegetables were significantly associated with a decrease in risk of developing transitional cell carcinoma of the urinary bladder in Scottish Terriers (Raghavan et al, 2005).…”