体内外实验测定淀粉的消化吸收特性

目的　采用体内外实验测定方法比较不同性质的淀粉 ,即可消化淀粉 (DS)和抗性淀粉 (RS)的消化吸收特性。方法　根据Englyst方法采用体外消化实验方法测定了 4种淀粉样品中DS、RS含量 ,再采用十二指肠灌注法直接将DS、RS注入到大鼠十二指肠 ,观察 4h内血糖变化 ,另采用代谢实验方法观察RS对碳水化合物和氮表观吸收率的影响 ,以及对消化酶分泌的影响。结果　体外实验表明 ,4种淀粉样品中以普通市售玉米淀粉DS含量最高 ,而马铃薯淀粉中 76 %为不消化的RS。动物实验表明 ,DS在十二指肠灌注后1 2 0min内血糖达到最大峰值 ;RS吸收相对缓慢 ,但总表观吸收率仍可达 96 %以上。另外RS可促进粪氮排出 ,降低氮表观吸收率 ,并可改变胃液和胃蛋白酶分泌。结论　利用体内外实验方法证明RS吸收缓慢但相对完全 ,部分佐证了Englyst以消化时间 1 2 0min作为界定DS和RS的方法     

抗性淀粉的代谢及对血糖的调节作用

目的 :　利用天然稳定同位素技术 ,探讨抗性淀粉吸收代谢的特点及对血糖调节的影响。方法 :　 7名健康志愿者分别试食 40 g天然富1 3C的葡萄糖、可消化淀粉 ( DS)和抗性淀粉( RS) ,测定餐后 0～ 2 40 min血糖 ,1 3C-血糖、血胰岛素水平和餐后 3 0 h呼气中1 3CO2 转化率及累积转化率。结果 :　食用 RS后 ,血糖和 1 3C-血糖水平明显低于食用葡萄糖和 DS;以葡萄糖餐后 1 2 0min的血糖生成指数 ( GI)和 1 3C-GI为 1 0 0 % ,RS的 GI值和 1 3C-GI值分别为 2 3 .5 8%和 5 5 .5 6% ;RS餐后呼气中1 3CO2 转化率的峰值明显低于葡萄糖和 DS( P<0 .0 5 ) ,但是 3 0 h累积转化率可达94.0 % ,与葡萄糖 ( 96.9% )和 DS( 1 0 2 .0 % )接近 ( P>0 .0 5 ) ;RS使餐后胰岛素升高幅度、胰岛素 /葡萄糖比值明显低于葡萄糖和 DS( P<0 .0 5 )。结论 :　抗性淀粉吸收缓慢但较完全 ,与葡萄糖和DS相比 ,具有维持餐后血糖稳态 ,提高机体胰岛素敏感性的作用     

锌对高糖高脂饲料喂养大鼠胰岛素敏感性影响

目的 探讨不同剂量锌对高糖高脂饮食大鼠胰岛素敏感性的影响.方法 健康雄性SD大鼠68只,随机分为正常饲料组(n=29)和高糖高脂组(n=39);喂养17周后正常饲料组和高糖高脂组再分别随机分成5组,分别给予蒸馏水、5、10、15、30 mg/kg锌灌胃,持续7周;测定大鼠血糖、空腹胰岛素(FINS)和糖化血红蛋白水平(HbA1c),计算稳态模型胰岛素抵抗指数(HOMA-IR)和胰岛素敏感指数(ISI).结果 正常饲料组和高糖高脂组大鼠在灌胃前后血糖差异均无统计学意义;与灌胃前比较,锌灌胃后高糖高脂组FINS、HOMA-IR均有不同程度升高(P＜0.05),高糖高脂+10、15 mg/kg锌组灌胃后FINS分别为(13.574±2.297)、(11.050±1.654) μIU/mL,均低于其他各组(P＜0.05);与灌胃前比较,锌灌胃后高糖高脂组ISI水平有不同程度降低,高糖高脂+15 mg/kg锌组灌胃后ISI水平为(-1.733±0.075),均低于其他各组(P＜0.05).结论 锌可在一定程度上提高高糖高脂饲料喂养大鼠胰岛素敏感性,但不同剂量锌效果存在差异.     

抗性淀粉对饮食诱发葡萄糖耐量异常的预防

目的 :　研究抗性淀粉对长期高蔗糖饮食诱发大鼠葡萄糖耐量异常的预防作用。方法 :　将 3 0只健康成年雄性 Wistar大鼠随机分成 3组 ,分别给予基础饲料、高蔗糖 (5 0 % )普通淀粉饲料 (HDS) ,高蔗糖抗性淀粉饲料 (HRS,含抗性淀粉 1 4% )。从第 4w开始每 2 w进行 1次口服葡萄糖耐量实验 ,至第 1 2 w为止。处死大鼠并收集血样、肝脏、肌肉等组织 ,测定血糖、胰岛素、糖化血红蛋白、血脂、血浆淀粉酶、肝糖原、肌糖原、红细胞膜 Na+ ,K+ - ATP酶活性等生化指标。结果 :　从第 1 0 w起 ,HDS组大鼠开始出现餐后血糖升高的现象 ,1 2 w时 HDS组大鼠餐后血糖和糖化血红蛋白明显高于对照组和 HRS组 (P<0 .0 5 ) ;肝糖原升高 ,而肌糖原降低 ,血浆淀粉酶和红细胞膜 Na+ ,K+ - ATP酶活性明显降低 ,与对照组相比 (P<0 .0 5 )。 HRS组大鼠除血浆淀粉酶活性低于对照组外 (P<0 .0 5 ) ,其他指标均与对照组没有显著性差别。结论 :　抗性淀粉可部分阻止高蔗糖饮食诱发的大鼠葡萄糖耐量异常的发生 ,这可能与降低餐后葡萄糖吸收 ,改善葡萄糖转运有关。     

大鼠的实验性铁与锌营养缺乏

目的观察铁锌同时缺乏和单独缺乏对大鼠铁锌营养状况的影响。方法按照2×2析因设计,将4w龄雄性wistar大鼠随机分为4组:缺铁缺锌组(F0Z0):喂以低铁低锌饲料(铁7.10mg/kg,锌5.14mg/kg),自由进食;单纯缺铁组(F0Z1):喂以低铁饲料(铁7.10mg/kg,锌40mg/kg);单纯缺锌组(F1Z0):喂以低锌饲料(锌5.14mg/kg,铁40mg/kg);铁锌正常组(F1Z1):喂以铁锌正常饲料(铁40mg/kg,锌40mg/kg);后3组均与F0Z0组对喂。喂养42d后,处死大鼠,分别测定Hb、Hct、血清铁、血清锌、肝脏铁、肝脏锌、胫骨锌等指标。结果实验结束时F0Z0组大鼠的Hb平均水平降至82.36g/L,血清锌0.78μg/ml,成功建立缺铁缺锌大鼠模型。4组大鼠的各项指标水平大多以F0Z0组最低,F0Z1组或F1Z0组次之,F1Z1组最高;铁缺乏可导致大鼠血清铁、肝脏铁含量明显下降,也可降低肝脏锌水平;锌缺乏能显著降低机体肝脏锌、胫骨锌水平;在体重、Hb、Hct、血清锌这四项指标上存在铁锌交互作用。结论大鼠铁锌同时缺乏时铁锌营养状况最差,缺锌可能会增加对铁的吸收利用,缺铁会减少体内锌储存量。     

营养

05 0 60 9　膳食钙对高脂膳食大鼠骨骼肌解偶联蛋白 3基因表达的影响 /于新凤…∥卫生研究 2 0 0 3 ,3 2 (3 ) 2 0 4～ 2 0 7为探讨膳食钙对高脂膳食大鼠骨骼肌解偶联蛋白3 (UCP3 )基因表达的影响 ,将雄性Wistar大鼠随机分成6组 ,每组 9只 ,分别喂以基础饲料A组 (0 5 %钙 )、高脂低钙饲料B组 (0 0 8%钙 )、高脂正常钙饲料C组(0 5 %钙 )、高脂高钙饲料D和E组 (1 %和 1 5 %钙 )和高脂高钙 (1 5 %钙 ) 维生素D(60 0IU % )饲料F组 ,9周后取血测全血血糖、血清瘦素、胰岛素、甲状腺激素 ,应用RT PCR方法测定骨骼肌UCP3mRNA表…     

褪黑素改善高糖高脂饲养大鼠胰岛素敏感性

目的:观察褪黑素对高糖高脂饲养大鼠胰岛素敏感性的影响。方法:将18只雄性SD大鼠(150~200g)随机分为正常组(CD组)与高糖高脂组(HFSD组),分别饲以正常饲料与高糖高脂饲料(53%基础饲料含蔗糖37%和猪油10%)喂养6个月后,给药治疗2个月;治疗期间,给褪黑素组(Mel组)每天腹腔注射药物褪黑素(Melatonin,Mel,4 mg/kg),对照组腹腔注射生理盐水。测定空腹血糖、胰岛素、甘油三酯(TG)、游离脂肪酸(FFA)、高密度脂蛋白胆固醇(HDL—C)水平,做口服葡萄糖耐量实验(OGTT)和胰岛素敏感性实验。结果:高糖高脂饮食可诱导SD大鼠产生胰岛素抵抗,引起SD大鼠空腹血糖、血清胰岛素、TG、FFA水平升高;胰岛素敏感性、HDL—C水平下降。褪黑素治疗后,胰岛素敏感性增强,改善了胰岛素抵抗。结论:Mel能降低高糖高脂饲养SD大鼠糖脂状况,提高胰岛素敏感性,改善胰岛素抵抗。     

初断乳大鼠锌补充对成年高脂诱导肥胖后胰岛素的影响

目的 探讨初断乳大鼠锌补充对成年期高脂饮食下胰岛素水平的影响,为阐明生命早期适量补锌预防成年后胰岛素抵抗的机制提供重要依据。方法 初断乳雄性SD大鼠85只随机分为基础饲料组和高、中、低锌补充组。锌补充4周后各组均以基础饲料喂养1周,于第5周末检测大鼠血糖、胰岛素水平并计算胰岛素抵抗指数。随后将基础饲料组大鼠随机分为肥胖组和正常对照组,肥胖诱导组及3个锌补充组均喂以高脂饲料。高脂干预8周后处死所有大鼠并检测上述指标。结果 大鼠成年高脂干预后,1)3个锌补充组分别较肥胖诱导组体重明显降低(P＜0.05),高脂饲料喂养后锌补充组体重正常,而肥胖诱导组发生肥胖;2)3个锌补充组分别较肥胖诱导组血糖、胰岛素明显降低(P＜0.05),而胰岛素抵抗指数明显升高(P＜0.05),高脂饲料喂养后锌补充组胰岛素水平正常,而肥胖诱导组产生胰岛素抵抗。结论 生命早期适量补锌可持续发挥作用,在一定程度上维持成年后高脂膳食下血糖和胰岛素处于正常水平,预防胰岛素抵抗发生。     

抗性淀粉对大鼠肝脏胆固醇代谢相关基因表达的影响

目的:观察抗性淀粉(RS)对大鼠肝脏胆固醇代谢相关基因表达的影响,探讨RS干预胆固醇代谢的作用机制。方法:将18只大鼠随机分为三组,分别饲食正常化学纯合饲料(对照组)、含15%RS纯合饲料(低RS组)和含30%RS纯合饲料(高RS组)6w。采用实时荧光定量PCR技术检测各组大鼠肝组织中胆固醇7a-羟化酶(CYP7A1)、肝清除细胞B1受体(SR-B1)、肝低密度脂蛋白受体(LDLR)mRNA表达水平。检测各组大鼠血胆固醇、盲肠内容物短链脂肪酸(SCFA)含量。结果:大鼠肝组织CYP7A1mRNA、SR-B1mRNA、LDLRmRNA表达水平及盲肠内SCFA含量,高RS组与对照组相比显著增加(P<0.05)。血清胆固醇水平,RS干预组显著低于对照组(P<0.05)。结论:RS通过增强肝组织胆固醇代谢相关基因表达水平,增加盲肠内SCFA含量,发挥降低血胆固醇的作用。     

高脂高糖饲料对建立实验糖耐量受损大鼠模型的效果分析

目的探讨脂肪和蔗糖对诱导大鼠糖耐量受损的作用及影响因素,并分析产出指标间的相互关系。方法选择两批不同体重的Wistar大鼠,分别随机分为4组(第2批)和5组(第1批),包括对照组和不同配比的高脂高糖饲料(HFS)组,每组至少10只。喂养8周后,通过测定体重、血糖和血脂变化,并采用多因素分析,比较脂肪、糖水平对引发大鼠糖耐量受损指症的影响。结果与对照组相比,高脂高糖饲料组大鼠体重显著增加,血糖、血脂明显升高,其增加幅度与鼠龄负相关(P0.05)。多因素分析结果显示:脂肪是引起大鼠体重增长、血糖、血脂异常的主要因素(P0.05),高脂高糖饲料引起的血糖耐量受损与脂肪摄入量的关系具有明显的统计学意义。高糖饲料对血糖的影响主要起到辅助增高的作用,但却可明显升高TG水平(P0.05),随着饲料中蔗糖水平增高TG上升趋势明显。结论制造糖耐量受损实验大鼠模型时,应尽量选择低龄大鼠;高脂高糖饲料中的蔗糖和脂肪配比要合理,以10%脂肪、20%蔗糖的比例较好。     

Effects of resistant starch RS4 on magnesium and iron absorption in Wistar rats

The effect of resistant starch RS4 on apparent absorption of magnesium and iron was studied in Wistar rats. The rats (4 groups male n=12 and 4 groups female n=12) were fed for 4 weeks diets: control with wheat starch (K) and 3 diets with modified resistant starches (S1, S2, S3). After an adaptation period (14 d), rats were transferred to metabolic cages. Dietary intake and faeces were monitored for 3 days. Mg and Fe levels were assessed in diets and feces by atomic absorption spectrometry. Apparent absorption of minerals was calculated as mineral intake minus fecal excretion and expressed as persentage of intake. Our results confirmed that Mg apparent absorption in female rats fed diet with resistant starch S2 was significantly increased (+37%) compared with the control group.     

Absorption and tissue distribution of zinc, iron and copper by rats fed diets containing lactalbumin, soy and supplemental sulfur-containing amino acids

Zinc, copper and iron utilization was examined in rats fed diets containing 30% lactalbumin (L); 30% soy assay protein (S) or 30% soy assay protein supplemented with 0.26% cysteine (SC), 0.45% methionine (SM), 0.26% cysteine and 0.45% methionine (SCM) or 0.71% cysteine (SXC). Diets L, SC and SCM contained equal amounts of cysteine; diets L, SM and SCM contained equal amounts of methionine; diets L, SCM, SXC contained equal amounts of sulfur-containing amino acids. Rats fed diet L had significantly higher levels of zinc in tibias, kidneys and plasma; higher levels of copper in kidneys; and higher levels of iron in tibias than rats fed diet S. Rats fed diet L also absorbed (apparent and true) significantly more zinc; excreted significantly more zinc of endogenous origin in the feces; and absorbed (apparent) significantly less copper than rats fed diet S. Rats fed the soy diets supplemented with sulfur-containing amino acids, especially diet SXC, tended to have elevated levels of zinc in their tibias and kidneys and greater apparent and true absorptions of zinc than rats fed diet S. Rats fed diet SXC still had significantly lower zinc levels in tissue than rats fed diet L. Apparent absorption of zinc was similar among rats fed diets L, SCM and SXC.     

Replacement of digestible wheat starch by resistant cornstarch alters splanchnic metabolism in rats.

Splanchnic metabolism was investigated in rats fed either a diet containing highly digestible wheat starch (DS diet) or amylase-resistant cornstarch (RS diet). In rats fed the latter diet, there was a considerable enlargement of the cecum and an increase in the production and absorption of volatile fatty acids (VFA), chiefly acetic and propionic acids. As a result, the major substrates absorbed from the digestive tract were glucose in rats fed the DS diet and both glucose and VFA in rats fed the RS diet. The liver removed about one-third of the absorbed glucose in rats fed the DS diet, whereas there was a slight release of glucose by the liver in rats fed the RS diet. Plasma insulin was higher in rats fed the DS diet, and there were smaller fluctuations of plasma insulin and liver glycogen between the fed and postabsorptive periods in rats adapted to the RS diet. In these animals, propionate was the major VFA taken up by the liver and approximately 50% of absorbed acetate was also removed by the liver. During the postabsorptive period, there was still a substantial contribution of VFA, especially propionate, to liver metabolism. A depressive effect of the RS diet on plasma triglycerides, cholesterol and free fatty acids was observed only during the postabsorptive period. Replacement of a large part of absorbed glucose by VFA apparently allows time for absorption of energy fuels to be extended and dampens the fluctuations of glucose metabolism during the light: dark cycle.     

Effects of dietary zinc levels, phytic acid and resistant starch on zinc bioavailability in rats

Summary Background Owing to its fermentability, it has been advocated that resistant starch (RS) has a positive effect on the absorption of minerals by increasing their solubility in the hindgut. In marginally zinc–deficient rats, the enhancement of zinc bioavailability by RS occurs mostly when the diet contains phytic acid. Aim of the study This study aims to investigate the effect of dietary zinc level and phytic acid on the cecal zinc pools and zinc bioavailability of rats fed RS. Methods Wistar rats (male, 3wk old) were divided into eight groups (n = 6), and fed diets containing either 5% cellulose (control fiber: insoluble and low fermentable) or 20 % RS (test fiber: soluble and fermentable), with or without the addition of 1% sodium phytate, at the 10 and 30 mg/kg dietary zinc levels, for 21 days. Results At 10 mg Zn/kg, RS increased femur zinc concentration only in the group receiving the phytate–containing diet, while at 30 mg Zn/kg it increased femur zinc concentration in rats fed both phytate–free and phytate–containing diets. The total content of zinc in the cecum was increased by the higher dietary zinc level and tended to be increased by the addition of phytate, which is assumed to impair zinc absorption in the small intestine. Feeding RS lowered cecal pH values, which correlated with increasing values of zinc solubility (r = –0.3471; P < 0.05). The later was, in turn, directly associated with zinc apparent absorption (r = 0.3739; P < 0.05). Conclusions The increase in zinc bioavailability by RS occurs when dietary zinc levels are adequate and/or zinc absorption is impaired in the small intestine, increasing the influx of unabsorbed zinc into the cecum and favoring the increase of zinc bioavailability when RS fermentation lowers the cecal pH.     

Cysteine-rich intestinal protein and intestinal metallothionein: an inverse relationship as a conceptual model for zinc absorption in rats.

Dietary zinc may regulate zinc absorption in part via the inhibitory effect of intestinal metallothionein, but the mechanism is unknown. We recently showed that cysteine-rich intestinal protein (CRIP) binds zinc during transmucosal zinc transport, and that CRIP may function as an intracellular zinc carrier. The present experiments examine the interaction of CRIP and metallothionein with zinc to evaluate their potential roles in the mechanism of zinc absorption. Intestinal metallothionein concentrations were lower and zinc absorption rates from isolated intestinal loops were higher in rats fed a low zinc diet compared with those fed a high zinc diet or given parenteral zinc to induce metallothionein synthesis. Zinc status did not affect the apparent CRIP concentration, but markedly altered the distribution of 65Zn in intestinal cytosol as determined by gel filtration HPLC. More 65Zn was associated with CRIP (40 vs. 14%) and less was bound to metallothionein (4 vs. 52-59%) in rats fed the low zinc diet compared with rats of high zinc status. Luminal zinc concentration also affected the distribution of 65Zn in the cytosol. CRIP bound progressively less (from 42 to 25%) of the 65Zn taken up from the lumen as the luminal zinc concentration was increased from 5 to 300 mumol/L. Collectively these data suggest that CRIP is a saturable, intracellular zinc transport protein, and that metallothionein inhibits zinc absorption by binding zinc in competition with CRIP. A hypothetical model for the mechanism of transcellular zinc absorption involving metallothionein and CRIP is presented and discussed.     

Effect of carbohydrates on lead absorption and retention in weanling rats

This study was designed to determine the effect of corn starch, lactose, and sucrose on lead (Pb) absorption and retention in rat tissues and organs. Seventy weanling Wistar male rats were assigned to the following five treatment groups: Group 1, 31.2% sucrose + 29.3% starch; Group 2, 31.2% lactose + 29.3% starch; Group 3, 60% corn starch (control); Group 4, 52.1% sucrose + 8.4% starch; Group 5, 52.1% lactose + 8.4% starch. All diets were supplemented with 200 ppm lead nitrate. The animals were fed the experimental diets for 8 weeks after which they were sacrificed. Analysis of lead in whole blood, bone (tibia and femur), carcass ash, and gut (alimentary canal) was done by atomic absorption spectrophotometric (AAS) technique. Results indicated that lactose in the diet caused increased lead retention by these tissues. Pb concentration was highest in blood (500% of the control) and bone (433% of control) of animals fed the Group 5 diet with the second highest level for the tissues of rats fed the Group 2 diet. Rats fed the high lactose diet showed the lowest weight gain and those fed the low sucrose diet showed the highest weight gain. The sucrose diets caused increased Pb in bone. In rats fed the sucrose diets, the Pb content of feces was greater than the value in rats fed the corn starch diet. The results of this study show that lactose has a higher stimulatory effect on Pb retention than sucrose.     

Fermentation of soybean flour with Aspergillus usamii improves availabilities of zinc and iron in rats

Soybean flour was fermented with Aspergillus usamii to improve the availabilities of dietary zinc and iron through the degradation of phytate. Three kinds of experimental diets that differed in protein sources were prepared: one consisting of 40% fermented soybean flour (RS diet), one consisting of 40% fermented soybean flour (FS diet), and one consisting of 20% regular soybean flour and 20% fermented soybean flour (RF diet). Zinc solubilities in the upper and the lower segments of the small intestine were higher in rats fed the FS diet than in rats fed the RS diet. The FS group showed higher solubility of iron in the lower small intestine than the RS group did. Zinc concentrations in the femur and plasma and iron concentrations in the liver and plasma were higher in the FS group than in the RS group. These results suggested that the fermentation of soybean flour improved the availabilities of dietary zinc and iron, which may be induced by increasing the solubilities of these minerals in the small intestine through the reduction of phytate content. Femoral and plasma zinc concentrations in the RF group were higher than in the RS group, but lower than in the FS group. No difference was noted in liver and plasma iron concentrations between the RF group and the FS group. Although phytase activity in FS degrades phytate in the RF diet, higher activity may be needed to degrade phytate completely.     

Studies of iron:zinc interactions in adult rats and the effect of iron fortification of two commercial infant weaning products on iron and zinc status of weanling rats

The effect of iron on zinc absorption in the rat, and vice versa, was investigated from single starch:sucrose test meals (containing 65Zn or 59Fe) by whole body counting. Zinc had no effect on iron absorption, but iron reduced zinc absorption when the total ionic species in the meal (iron plus zinc) reached 1.36 mg. Below this level, high iron:zinc molar ratios (10:1) had no effect on zinc absorption, presumably because the transport mechanism for zinc had not reached full capacity. Previous iron intake had no effect on zinc absorption. The relevance of these findings to infant foods was explored by feeding rats exclusively a vegetable or cereal weaning product, with or without additional iron, for 12 d and measuring zinc and iron status. The added iron raised body iron stores and caused a small reduction in zinc status in animals fed the oat, but not the vegetable, diet as measured by plasma and femur zinc concentrations. Since the threshold level of 1.36 mg ionic species would be exceeded when the animal ate 3-4 g of the iron-fortified weaning food at any one time, it appears that the iron:zinc interactive effect was absent in the vegetable and less potent in the oat formulation than in a carbohydrate test meal. Alternatively, it may be the case that the animals had responded over time to reduced zinc availability by increasing whole body zinc retention.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of sucrose and starch on the development of anemia in copper- and iron-deficient rats

The purpose of this investigation was to compare the effects of sucrose and starch on the development of copper and iron deficiency. Male Sprague-Dawley rats (n = 48) were fed one of eight diets in a 2 X 2 X 2 factorial design for 24 d. Two levels of copper (deficient, 0.7 microgram/g, or adequate, 8.3 micrograms/g) and iron (deficient, 8.3 micrograms/g, or adequate, 50 micrograms/g), and two types of carbohydrate (sucrose or starch, 62% of the diet) were fed. Copper-deficient rats had significantly lower hematocrit, hemoglobin and tibia iron levels and depressed copper and iron absorption when fed sucrose instead of starch. The apparent absorption of copper, but not iron, was significantly lower when rats deficient in both copper and iron were fed sucrose rather than starch. Iron-deficient rats fed sucrose apparently absorbed significantly more iron than those fed starch; however, sucrose did not significantly improve hematocrit and hemoglobin levels. The metabolism of copper and iron by rats fed diets adequate in these nutrients was not affected by the type of dietary carbohydrate. These data indicate that the type of dietary carbohydrate alters both copper and iron metabolism, particularly in copper-deficient rats.