X-Message-Number: 25101 Date: Thu, 18 Nov 2004 20:32:07 -0800 (PST) From: Doug Skrecky <> Subject: apples, spinach, spirulina versus Alzheimer's? Antioxidant-Rich Diets Improve Age-Related Declines In Mental Function Of Rats Tampa, FL (July 15, 2002) - Popeye was right - eat your spinach. In fact, add some fresh-cut apples to that spinach salad. Two new animal studies by researchers at the University of South Florida Center for Aging and Brain Repair and James A. Haley Veterans Hospital bolster a growing body of evidence that certain fruits and vegetables may protect the brain against the ravages of age. The complementary research papers appear in today's issue of the Journal of Neuroscience. "If these pre-clinical findings translate to humans, it suggests that eating a diet high in antioxidant-rich fruits and vegetables may help reverse declines in learning and memory as you get older," Paula Bickford, PhD, lead author of both studies and a professor at the USF Center for Aging and Brain Repair. In the first study, co-authored by USF's M. Claire Cartford, PhD, older rats fed a diet rich in spinach for six weeks showed a reversal in the normal loss of learning that occurs with age. The rats that ate rat chow containing 2 percent freeze-dried spinach learned to associate the sound of a bell tone with a subsequent puff of air faster than those fed regular rat chow, the study found. The test measured how quickly the rats learned to blink, after hearing the tone, in anticipation of the oncoming puff of air - a conditioned response shown to slow with age in rodents and humans. Spinach is rich in antioxidants, which scientists say can counteract free radicals generated in the body during normal metabolism and exposure to environmental insults such as pollution, ultraviolet light and radiation. An excess of free radicals can damage cellular lipids, protein and DNA. Studies suggest that a lifelong accumulation of free radicals can slow mental processes in old age and may be a factor in Alzheimer's and Parkinson's diseases, Dr. Bickford said. The second study, co-authored by Carmelina Gemma, PhD, of USF and James A. Haley VA Hospital, found that the benefit of a diet high in fruits and vegetables depends on the levels of antioxidant nutrients in the fruits and vegetables. Furthermore, the researchers suggest, the protective effect of antioxidants may be linked to their ability to reverse age-related accumulations of potentially harmful inflammatory substances in the brain. The USF researchers compared three groups of older rats. One group ate a diet supplemented by spirulina, a blue-green algae high in antioxidant activity. The second group was fed a daily ration of apple, a food moderate in antioxidant activity, with their rat chow. The third group ate a cucumber-enriched diet, low in antioxidant activity. Aged rats fed either spirulina-or apple-enriched diets for two weeks demonstrated improved neuron function, a suppression of inflammatory substances in the brain, and a decrease in malondialdehyde (MDA), a marker for oxidative damage. In fact, spirulina reversed the impairment in adrenergic neural function normally associated with aging. There was no improvement in rats fed a diet supplemented with cucumber. "Not all foods are cr eated equal," Dr. Bickford said. "Cucumbers taste good and have lots of fiber. But unlike spirulina and apples, they are not rich in phytochemicals that have antioxidant or anti-inflammatory effects in the brain." The research has hopeful implications for the prevention of neurodegenerative disorders in an increasingly aging population, but still must be tested in humans, Dr. Bickford said. Until then, the USF neuroscientist recommends that daily diets include a variety of richly colored fruits and vegetables - the most colorful ones tend to pack the greatest antioxidant punch. She favors spinach salads for lunch and routinely snacks on blueberries and strawberries. "Studies like these are lending scientific credibility to what nutritionists, and our mothers, have been telling us for years," Dr. Bickford said. "Eat your fruits and vegetables. They're good for you!" Researchers at the University of Colorado Health Sciences Center and Denver Veterans Affairs Medical Center contributed to the study on diets enriched with spirulina, apples and cucumbers. J Neurosci. 2002 Jul 15;22(14):5813-6 Eighteen-month-old Fischer 344 rats fed a spinach-enriched diet show improved delay classical eyeblink conditioning and reduced expression of tumor necrosis factor alpha (TNFalpha ) and TNFbeta in the cerebellum. Diets high in antioxidant properties are known to reverse some deficits in neuronal and cognitive function that occur in aging animals. Antioxidants are also known to reduce levels of proinflammatory factors in the CNS. We report here that 6 weeks of a spinach-enriched diet ameliorates deficits in cerebellar-dependent delay classical eyeblink learning and reduces the proinflammatory cytokines tumor necrosis factor alpha (TNFalpha) and TNFbeta in the cerebelli of eyeblink-trained animals. Eighteen-month-old Fischer 344 rats were given spinach-enriched lab chow or regular lab chow for 6 weeks. The rats were then given 6 d of 30 trials per day training using a 3 kHz tone conditioned stimulus and airpuff unconditioned stimulus. Rats were killed 3 weeks after eyeblink training. Cytokine expression was measured using RNase protection assay analysis in the eyeblink-trained animals and in a group of young control animals given regular lab chow diet. Old animals on the spinach-enriched lab chow diet learned delay eyeblink conditioning significantly faster than old animals on the regular diet. Cerebelli fr om older animals on the spinach-enriched diet had significantly less TNFalpha and TNFbeta than cerebelli from older animals on the control diet. J Neurosci. 2002 Jul 15;22(14):6114-20 Diets enriched in foods with high antioxidant activity reverse age-induced decreases in cerebellar beta-adrenergic function and increases in proinflammatory cytokines. Antioxidants and diets supplemented with foods high in oxygen radical absorbance capacity (ORAC) reverse age-related decreases in cerebellar beta-adrenergic receptor function. We examined whether this effect was related to the antioxidant capacity of the food supplement and whether an antioxidant-rich diet reduced the levels of proinflammatory cytokines in the cerebellum. Aged male Fischer 344 rats were given apple (5 mg dry weight), spirulina (5 mg), or cucumber (5 mg) either in 0.5 ml water by oral gavage or supplied in the rat chow daily for 14 d. Electrophysiologic techniques revealed a significant decrease in beta-adrenergic receptor function in aged control rats. Spirulina reversed this effect. Apple (a food with intermediate ORAC) had an intermediate effect on cerebellar beta-adrenergic receptor physiology, and cucumber (low ORAC) had no effect, indicating that the reversal of beta-adrenergic receptor function decreases might be related to the ORAC dose. The mRNA of the proinflammatory cytokines tumor necrosis factor-alpha (TNFalpha) and TNFbeta was also examined. RNase protection assays revealed increased levels of these cytokines in the aged cerebellum. Spirulina and apple significantly downregulated this age-related increase in proinflammatory cytokines, whereas cucumber had no effect, suggesting that one mechanism by which these diets work is by modulation of an age-related increase in inflammatory responses. Malondialdehyde (MDA) was measured as a marker of oxidative damage. Apple and spirulina b ut not cucumber decreased MDA levels in the aged rats. In summary, the improved beta-adrenergic receptor function in aged rats induced by diets rich in antioxidants is related to the ORAC dose, and these diets reduce proinflammatory cytokine levels. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=25101