Biomedical subjects

T R Overton

Publications and source records attributed to T R Overton.

At least 37 records · Page 2Linked to original sources

PubMed2000

Protein nutrition in late pregnancy, maternal protein reserves and lactation performance in dairy cows.

Empirical evidence suggests that prolonged underfeeding of protein to late-pregnant dry cows can have modest negative carry-over effects on milk volume and/or protein yield during early lactation, and may also cause increased incidence of metabolic diseases associated with fatty liver. However, assessment of requirements is hampered by lack of information on relationships between dietary intake of crude protein (N x 6.25) and metabolizable protein supply during late pregnancy, and by incomplete understanding of the quantitative metabolism of amino acids in maternal and conceptus tissues. Inability of the postparturient cow to consume sufficient protein to meet mammary and extra-mammary amino acid requirements, including a significant demand for hepatic gluconeogenesis, necessitates a substantial, albeit transient, mobilization of tissue protein during the first 2 weeks of lactation. Ultimately, much of this mobilized protein appears to be derived from peripheral tissues, especially skeletal muscle and, to a lesser extent, skin, through suppression of tissue protein synthesis, and possibly increased proteolysis. In the shorter term, soon after calving, it is likely that amino acids required for hepatic glucose synthesis are diverted from high rates of synthesis of splanchnic tissue and export proteins, including serum albumin. The prevailing endocrine milieu of the periparturient cow, including major reductions in plasma levels of insulin and insulin-like growth factor-I, together with insulin resistance in peripheral tissues, must permissively facilitate, if not actively promote, net mobilization of amino acids from these tissues.

Animal Nutritional Physiological Phenomena↗

PubMed1999

Longitudinal changes in radial bone density in older men.

OBJECTIVE: To examine changes in radial bone density and biochemical status, with particular reference to calcium, over 18 months in a group of older men. SUBJECTS: Thirty-six healthy men (aged 66 76 y) were recruited to the study during July and August, 1993. These men were free-living residents of Edmonton who were recruited through local organizations for the retired and semi-retired. Data for the younger group of men (age 29-60 y) were taken from a previous study conducted in our laboratory. DESIGN: using special-purpose computed tomography (gammaCT), trabecular (TBD), cortical (CBD) and integral (IBD) bone densities (gm/cm3) were measured in the ultra-distal radius at 6-month intervals over 18 months. At baseline, and at each subsequent study visit, serum was obtained from each subject for determinations of calcium, phosphate, 25-hydroxyvitamin D, alkaline phosphatase, and immunoreactive parathyroid hormone. A 24-h urine sample was also obtained at each study visit for determination of urinary calcium, phosphate and creatinine. RESULTS: In repeated measures analysis of variance of the data for the older men serum 25-hydroxyvitamin D was significantly decreased (P<0.001) over time, while TBD was increased (+0.60% per year, P<0.01). Longitudinal rates of change for TBD, CBD and IBD were: -0.94%, 0.92% and 0.74% per year respectively when bone density data at baseline for the older men and the historical data for younger men were combined. However, separate analyses of the data for the younger and the older men indicated no significant age-related changes in bone density for men aged 29-60 y, or for men aged 66-76 y. However, differences in TBD, CBD and IBD between the younger and older groups of men were significant (P < 0.001). CONCLUSIONS: In a group (n = 36) of older men (mean age 71.7 y) studied longitudinally over 18 months, bone density in the distal radius did not decrease over time. Mean bone density in this group of men was, however, significantly (P < 0.001) lower than in a group of younger men (n = 17, mean age 46.7 y). Regression analysis using cross-sectional bone density data at baseline for the older male group, and historical data for the younger male group, indicates that bone loss occurs with increasing age at a rate of about 1% per year averaged over ages 29-76 y. Bone density variables were not correlated with either height or weight, or with any biochemical or hormonal variable measured in this study.

Adult↗

PubMed1999

Substrate utilization for hepatic gluconeogenesis is altered by increased glucose demand in ruminants.

Hepatocytes isolated from 10 Dorset wethers that were treated with excipient or 1.0 g/d of phlorizin for 72 h were used to determine the effects of increased glucose demand on utilization of [1-(14)C]propionate and [1-(14)C] alanine for oxidative metabolism and gluconeogenesis. Control and phlorizin-treated wethers excreted 0 and 62.8 g/d of glucose into the urine, respectively. Phlorizin treatment tended to increase conversion of propionate and alanine to CO2. A phlorizin x substrate interaction for conversion to glucose indicated that conversion of alanine to glucose was increased more by phlorizin treatment than was conversion of propionate (285 vs 166% of controls). Phlorizin treatment did not affect estimated Ks for conversion of substrates to either CO2 or glucose; however, phlorizin increased estimated Vmax for conversion of substrates to CO2 and tended to increase estimated Vmax for conversion of substrates to glucose. Phlorizin treatment slightly increased the ratio of conversion of propionate to glucose compared with CO2 and slightly decreased the ratio of conversion of alanine to glucose compared with CO2. In vitro addition of 2.5 mM NH4Cl decreased conversion of propionate to CO2 and glucose but had little effect on conversion of alanine to CO2 and glucose. Estimated Ks and Vmax for conversion of substrates to CO2, Ks for conversion of substrates to glucose, and Vmax for conversion of alanine to glucose were not affected by NH4Cl; however, Vmax for conversion of propionate to glucose was decreased by NH4Cl. These data indicate that although utilization of propionate for gluconeogenesis is extensive, amino acids have the potential to increase in importance as gluconeogenic substrates when glucose demand is increased substantially. Furthermore, excess ammonia decreases the capacity of hepatocytes to utilize propionate for oxidation and gluconeogenesis.

Alanine↗

PubMed1998

Metabolic adaptation to experimentally increased glucose demand in ruminants.

Four Dorset wethers were studied in a Latin square design with 72-h periods to determine the metabolic adaptations that occur in support of increased glucose demand in ruminants. Wethers injected at 8-h intervals with excipient or a total of .5, 1.0, or 2.0 g/d of phlorizin excreted an average of 0, 72.7, 97.9, and 98.5 g/d of glucose into the urine, respectively. Both acute (2 to 24 h after the first injection) and chronic (8-h intervals from 8 to 72 h after the first injection) adaptations of plasma variables to phlorizin treatment were assessed. Concentrations of plasma glucose decreased linearly with increasing phlorizin dose during the 1st 24 h of treatment and tended to decrease linearly with phlorizin dose during 8 to 72 h of treatment. Urea N tended to increase linearly during 2 to 24 h and increased linearly during 8 to 72 h. Nonesterified fatty acids increased linearly with phlorizin injection during the entire treatment period. beta-Hydroxybutyrate increased quadratically with phlorizin injection during 2 to 24 h and tended to increase quadratically during 8 to 72 h. The ratio of insulin to glucagon tended to decrease linearly with phlorizin injection during the 1st 24 h but was unaffected from 8 to 72 h. Triiodothyronine, but not thyroxine, tended to decrease linearly with phlorizin injection during 8 to 72 h. Cortisol was not affected by treatment. Digestibilities of energy and N were not affected by treatment. Urinary energy excretion increased with phlorizin injection in proportion to the amounts of glucose excreted into the urine. These data indicate that phlorizin-treated wethers largely adapted to phlorizin treatment by 24 h after the first injection and are a suitable model for further investigations of hepatic adaptation to increased glucose demand in ruminants.

3-Hydroxybutyric Acid↗

PubMed1998

Supplemental fat and nicotinic acid for Holstein cows during an entire lactation.

The objectives of this experiment were to determine long-term responses to supplemental fat (from whole soybeans and liquid animal fat) and to determine whether the supplementation of nicotinic acid would enhance milk protein content or yield. From wk 4 through 43 postpartum, 44 multiparous Holstein cows (10 to 12 per treatment) were assigned to one of four dietary treatments: 1) control, 2) control plus 12 g/d of nicotinic acid, 3) supplemental fat, and 4) supplemental fat plus 12 g/d of nicotinic acid. The dry matter intake of cows did not differ among dietary treatments. Yields of milk, solids-corrected milk, and 3.5% fat-corrected milk were increased by nicotinic acid; the yield of fat-corrected milk during wk 4 to 25 was increased by supplemental fat. Contents of crude protein (CP) and true protein in milk were less for cows fed diets supplemented with fat or nicotinic acid; casein content was decreased by nicotinic acid. Intake of net energy for lactation was greater for cows fed supplemental fat; energy balance was greater during wk 4 to 25 for cows fed diets supplemented with fat. Body condition score and body weight were less when nicotinic acid was added to the control diet than when it was added to the diet supplemented with fat. Supplemental fat increased the concentration of nonesterified fatty acids (NEFA) in plasma; nicotinic acid increased NEFA when it was added to the control diet but decreased NEFA when it was added to the diet supplemented with fat. Nicotinic acid did not prevent the decrease in milk CP content that was induced by dietary fat, but it did increase milk yield and tended to increase the yield of milk CP.

3-Hydroxybutyric Acid↗

PubMed1998

Effects of source of carbohydrate and protein and rumen-protected methionine on performance of cows.

Multiparous Holstein cows were fed diets consisting of alfalfa silage, corn silage, and a concentrate mixture containing primarily ground shelled corn or corn gluten feed; the diets were supplemented with 0 or 20 g/d of rumen-protected Met. The 183-d experimental period followed a 21-d covariate period beginning at calving. Data from early lactation (d 22 to 105) and the entire experiment were analyzed. Yields of milk and milk crude protein were not affected by treatment. Corn gluten feed increased the percentages of milk fat and total solids. The rumen-protected Met tended to increase both the crude protein and casein N content of milk. Body weight, milk fat percentage, and yields of milk fat, 3.5% fat-corrected milk, and total solids were greater when ground shelled corn and 20 g/d of rumen-protected Met or corn gluten feed and 0 g/d of rumen-protected Met were fed than when ground shelled corn and 0 g/d of rumen-protected Met or corn gluten feed and 20 g/d of rumen-protected Met were fed. A similar interaction for dry matter intake was significant only during d 22 to 204. Corn gluten feed increased plasma concentrations of His, Ile, Leu, and Val. Rumen-protected Met increased plasma concentrations of Met, decreased His, and tended to decrease Arg, Lys, and Orn. These data suggest that the dietary source of carbohydrate and protein can modulate the response of cows to rumen-protected Met.

Amino Acids↗

PubMed1998

Effects of Yucca shidigera extract and soluble protein on performance of cows and concentrations of urea nitrogen in plasma and milk.

Twelve multiparous Holstein cows averaging 122 d postpartum were used in a replicated Latin square design with 21-d periods. Cows were fed diets containing either low or high soluble protein supplemented with 0 or 9 g/d of Yucca shidigera extract per cow. Dry matter intake and yields of milk, fat, 3.5% fat-corrected milk, and total solids were not affected by treatment. High soluble protein increased percentages of fat and total solids in milk but decreased percentages of crude protein and true protein in milk. Yucca shidigera extract did not affect percentages or yields of milk components, ruminal NH3 N, or urea N in milk or plasma. High soluble protein tended to increase both ruminal pH and concentrations of ruminal NH3 N. Yucca shidigera extract did not affect ruminal pH or NH3 N. High soluble protein increased concentrations of urea N in plasma and milk when both were measured by enzymatic assay, but differences in milk urea N measured by mid infrared reflectance spectroscopy were not significant. Neither Yucca shidigera extract nor increased ruminally undegradable protein was beneficial in this trial when fed to cows milking 30 to 35 kg/d. Concentrations of urea N in milk as measured by mid infrared reflectance spectroscopy were higher than those measured by enzymatic assay, but measurements by mid infrared reflectance spectroscopy were not as sensitive to treatment differences as were measurements by enzymatic assay.

Ammonia↗

PubMed1997

Production and composition of milk from Jersey cows administered bovine somatotropin and fed ruminally protected amino acids.

Eight multiparous and 4 primiparous Jersey cows averaging 92 d of lactation were utilized in a replicated 4 x 4 Latin square design with 28-d periods to determine responses to bovine somatotropin (bST) and ruminally protected Met and Lys when diets were fed that contained supplemental fat. Treatments were 1) control [no bST or ruminally protected amino acids (AA)], 2) control plus bST, 3) control plus ruminally protected AA, and 4) control plus bST plus ruminally protected AA. Dry matter intake was increased by bST but was unaffected by ruminally protected AA. Milk yield was increased by bST but was not altered by ruminally protected AA compared with the control diet. The bST tended to increase percentages of fat and total solids in milk and increased yields of fat, protein, 3.5% fat-corrected milk, and total solids. Ruminally protected AA increased percentages of fat, protein, and total solids in milk; however, yields of milk components were unaffected by ruminally protected AA. Body weight and body condition scores were unaffected by treatment. Concentrations of essential AA in plasma were unaffected by bST administration. Ruminally protected Met and Lys increased the concentration of Met and tended to increase the concentration of Lys in plasma. The lack of an increase in yields of milk and milk protein when ruminally protected AA were fed suggests that adequate amounts of Met and Lys were supplied by the control diet and protein reserves of the cows to meet the AA requirements for synthesis of milk and milk components.

Amino Acids↗

PubMed1996

Quantitative radiographic changes in the mandible, femur and vertebra in lactating rats fed a low-calcium diet.

OBJECTIVE: To determine whether similar changes occur in the mandible, femur and vertebral body in generalized osteopenia. METHODS: Osteopenia was induced in the bred animal group using a low calcium diet from parturition onwards. Control groups were virgin and bred rats fed a normal diet. Rats in each group were weighed weekly, and subgroups of 12 rats in each treatment group were killed at ages 18, 24, 36 and 48 weeks. A separate reference group of 12 rats was killed at age 12 weeks, i.e. day 0 of the comparative study. The mandibles, both femurs and the first lumbar vertebrae of all rats were removed post-mortem and radiographs made for each individual bone; measurements of cortical thickness and bone widths were made from these radiographs using a computer-based video image analysis system. RESULTS: Significant differences among treatment groups were detected for each bone type; changes were sustained over the 48-week study period for the femur and vertebrae but were transient, except for alveolar bone height, in the mandible. Significant differences were found for cortical thicknesses and bone widths in the mandible, femur and vertebrae, based on the duration of the low-calcium diet. Although significant differences in the thickness of some cortices were found in the mandible, dimensional changes were small. CONCLUSIONS: Mandibular cortical width is an unreliable indicator of osteopenia in this rat model.

Analysis of Variance↗

PubMed1996

Evaluation of a ruminally protected methionine product for lactating dairy cows.

In Experiment 1, three ruminally and duodenally cannulated cows were used to assess the extent of ruminal protection and postruminal release of Met from ruminally protected Met using a polyester bag technique. The ruminally protected Met contained 85.1% DL-Met (wt/wt). Ruminal disappearance of Met averaged 5.8, 8.1, 21.8, 37.5, and 87.5% after 3, 6, 12, 24, and 96 h of incubation, respectively. Postruminal disappearance of Met from bags inserted in the duodenum after treatment with pepsin-HCl averaged 63.4, 62.6, 51.6, 43.6, and 8.8% for bags incubated in the rumen for 3, 6, 12, 24, and 96 h, respectively. In Experiment 2, 12 cows were fed either 0 or 20 g/d of ruminally protected Met from 7 to 10 d prepartum until 18 wk postcalving. Cows were fed the same total mixed diet. The DMI; yields of milk, CP, and SNF; and percentages of fat, CP, and SNF in milk were not affected by treatment. However, yields of fat and 3.5% FCM increased when ruminally protected Met was fed. Milk N components were not affected by treatment. Concentrations of Met increased in plasma when ruminally protected Met was fed. The mechanism for the increased production of milk fat and 3.5% FCM when ruminally protected Met was fed is unknown.

Amino Acids↗

PubMed1996

Effects of dietary fat with or without nicotinic acid on nutrient flow to the duodenum of dairy cows.

Four Holstein cows, fitted with ruminal and duodenal cannulas, were utilized in a 4 x 4 Latin square design to investigate the effects of supplementing nicotinic acid to diets that contained 35% alfalfa haylage, 15% corn silage, and either 50% of a low fat concentrate or 10% whole raw soybeans and 40% of a high fat concentrate containing tallow. Treatments in a 2 x 2 arrangement were 1) low fat, no supplemental nicotinic acid; 2) low fat, 12 g/d of nicotinic acid; 3) high fat, no supplemental nicotinic acid; and 4) high fat, 12 g/d of nicotinic acid. The DMI and OM apparently and truly digested in the rumen and apparently digested postruminally were not different among treatments. Addition of fat to the diet decreased the concentration of total VFA in ruminal fluid but did not alter the molar proportions of any of the VFA; supplementation of nicotinic acid tended to decrease the molar proportion of acetate. Amounts of NAN, microbial N, nonammonia nonmicrobial N, and AA that flowed to the duodenum were similar among diets. The concentration of urea N in plasma decreased, and concentrations of cholesterol and triglycerides increased, when cows were fed supplemental fat. Milk composition and production of milk, 4% FCM, and milk components were not altered by addition of fat or nicotinic acid to the diet. Supplementation of fat or nicotinic acid to diets of dairy cows was not beneficial in this experiment.

Animal Nutritional Physiological Phenomena↗

PubMed1996

Response of cows fed a low crude protein diet to ruminally protected methionine and lysine.

Ten cows (mean = 128 DIM) were utilized in a replicated 5 x 5 Latin square design and fed diets formulated to supply adequate (18% CP) or inadequate (14% CP) Met and Lys. A prototype supplement of ruminally protected Met and Lys was added to the 14% CP diet to provide 0, 50, 100, and 150% of the predicted deficiency of Met and Lys. The DMI; yields of milk, 3.5% FCM, total N, protein N, and whey N; plasma concentrations of Arg, Cit, His, Ile, Leu, Orn, Phe, Pro, Tyr, Val, and urea N were greater for cows fed the 18% CP diet. Supplementing ruminally protected Met and Lys to the 14% CP diet did not affect DMI or yields of milk, 3.5% FCM, milk CP, and milk SNF. Milk fat yield was affected quadratically because it was greater when 0 or 150% of the deficiency of Met and Lys was supplied. Percentages of CP and casein N in milk increased linearly as cows were fed increasing amounts of ruminally protected Met and Lys. Plasma concentrations of urea N, Met, and Lys increased when ruminally protected Met and Lys were fed; however, other nutrients probably were limiting for synthesis of milk and milk protein when cows were fed a 14% CP diet because yields of each were not increased by ruminally protected Met and Lys.

Amino Acids↗

PubMed1995

Ruminal fermentation and passage of nutrients to the duodenum of lactating cows fed mixtures of corn and barley.

Five Holstein cows were used in a 5 x 5 Latin square design and fed diets containing five different ratios of starch from ground shelled corn and steam-rolled barley. The DMI decreased and both the proportions of OM and starch digested in the rumen increased as barley starch increased in the diet. Corn and barley starches fed in a ratio of 75:25 maximized the proportions of ADF and NDF digested in the rumen. Replacement of 25% of the corn starch with barley starch resulted in the largest increase in the molar percentage of propionate and the largest decrease in the molar percentage of acetate in ruminal fluid. Passage of NAN to the duodenum was not affected by treatment; however, the percentage of nonammonia nonmicrobial N in NAN decreased as barley starch increased. Passage of AA to the duodenum was largest when corn and barley starches were fed in ratios of 100: 0 and 0:100 because of the influence of DMI and microbial protein synthesis. Production of Milk, CP, and SNF was similar when cows were fed diets containing corn and barley starches in ratios of 100:0, 75:25, and 50:50 but was decreased when the ratios were 25:75 and 0:100. Increased production responses of cows when diets contained larger amounts of starch from ground shelled corn were probably due to increased DMI.

Amino Acids↗

PubMed1994

Kinetics of niacin supplements in lactating dairy cows.

The kinetics of niacin supplements in lactating dairy cows and the stability of supplements during in vitro fermentation were examined. Four multiparous Holstein cows (200 DIM) with ruminal and duodenal cannulas were fed a TMR either unsupplemented or supplemented with 12 g/d of nicotinic acid, 12 g/d of nicotinamide, or 6 g/d combination of each niacin source in a 4 x 4 Latin square design. Ruminal and duodenal concentrations of nicotinic acid increased with niacin supplementation, but DMI, yields of milk and FCM, most measures of milk composition, ruminal VFA, and plasma NEFA and BHBA concentrations were unaffected by niacin supplementation at this stage of lactation. Apparent digestibilities of most nutrients were greater when both sources of niacin were supplemented than when either source was supplemented separately. Duodenal nicotinic acid concentrations were higher for cows supplemented with nicotinamide than for cows receiving nicotinic acid, but the opposite was true for nicotinic acid concentrations in plasma. The results of both experiments indicated that nicotinamide was converted rapidly to nicotinic acid by microorganisms in the reticulorumen. Supplementation with either nicotinic acid or nicotinamide effectively can increase the amount of nicotinic acid available to the cow; however, some source effects remain to be explained.

Animal Feed↗

PubMed1994

Digestibility and effects of three forms of mostly saturated fatty acids.

Four nonlactating Holstein cows fitted with ruminal cannulas were used in a 4 x 4 Latin square design with 14-d periods. Treatments were 1) control, no added fat; 2) 5.0% prilled fatty acids (iodine value = 14); 3) 5.6% prilled hydrogenated tallow (iodine value = 8); and 4) 5.0% flaked fatty acids (iodine value = 14). Diets consisted of alfalfa haylage, corn silage, and concentrate (40:20:40, DM basis). Intake of the TMR (16.4% CP and 25.4% ADF) was restricted to 1.5% of BW so that DMI was similar among diets (9.2 kg/d). Total fatty acid intakes averaged 293, 749, 747, and 686 g/d for treatments 1 to 4, respectively. Digestibilities of total C16, total C18, and total fatty acids were greater for prilled fatty acids than for prilled hydrogenated tallow. Total tract apparent digestibilities of DM, OM, CP, ADF, and NDF did not differ among treatments. Treatments did not affect concentration of total VFA or acetate:propionate ratio in ruminal fluid. Concentration of cholesterol in plasma was lowest when cows were fed the control diet and was greater when cows were fed prilled fatty acids than when they were fed prilled hydrogenated tallow or flaked fatty acids. The three forms of saturated fatty acids did not affect nutrient digestibilities or ruminal fermentation characteristics, but the digestibility of fatty acids in prilled hydrogenated tallow was lower than in prilled fatty acids. Digestibilities of fatty acids and other nutrient fractions and characteristics of ruminal fluid generally were similar between flaked and prilled fatty acids, despite the larger particle size of flaked fatty acids.

Animals↗

PubMed1992

Bone mass measurements in the distal forearm using dual-energy x-ray absorptiometry and gamma-ray computed tomography: a longitudinal, in vivo comparative study.

Indices of bone mass were measured in 23 volunteers weekly over 14-16 weeks using dual-energy x-ray absorptiometry (DEXA) and special-purpose computed tomography (gamma-CT). In vitro, the precision for both systems was excellent (coefficient of variation less than 0.5%). Over 4 months, the precision in vivo (average CV for all subjects) for DEXA measures (BMD, g/cm2, and BMC, g/cm) varied between 0.6 and 1.1%; with gamma-CT it varied from 1.1% for TBD (g/cm3) to 2.2% for CBD (g/cm3). Correlation between the indices of bone mass measured using DEXA and gamma-CT at the ultradistal site was moderate, but these indices were not correlated at the distal third site. When BMD and BMC were derived from the CT index IBD, however, the correlation between these gamma-CT indices and the corresponding DEXA indices was high for both ultradistal and proximal radial sites.

Absorptiometry, Photon↗

PubMed1992

Changes in the linear attenuation coefficient of canine appendicular bone following intravenous infusion of strontium lactate, measured using gamma-ray computed tomography.

Changes in the average linear attenuation coefficient (LAC) within a fixed measurement volume in the proximal end of the dog tibia, which contains trabecular bone and associated soft tissues (the trabecular bone "space"), were monitored continuously using gamma-ray computed tomography (gamma-CT) prior to, during, and following intravenous infusion of strontium (Sr) lactate. An infusion of 1.3-4.7 g of Sr over a period of 110-160 minutes into 20-kg dogs resulted, within 6-8 hours, in an increase of 0.019-0.045 cm-1 (P less than 0.002) in the LAC. Calibration of the gamma-CT system showed that 0.44 mg/cm3 of Sr produced a change of 0.01 cm-1 in the LAC. Using this conversion factor, the Sr concentration in the trabecular bone space resulting from infusion, as measured by flame atomic absorption spectroscopy, agreed with that predicted by the change observed in the LAC. Sr present in the serum and urine was consistent with the changes observed in the LAC over the study period. Control dogs infused with mineral-free solutions showed no change in LAC. Calcium equivalents required to give the changes observed in the LAC using Sr indicate that variations in skeletal turnover in man can be monitored in the peripheral skeleton using gamma-CT.

Animals↗

PubMed1992

Vitamin B12 and folate status of a selected group of free-living older persons.

Vitamin B12 and folate status was determined in 50 male and 47 female free-living subjects (65-77 years) in winter and summer. The mean intake calculated from 3-day food records met the Canadian recommended intake (RNI) for both gender and season, however, probability analysis of dietary data revealed a number of subjects at risk of deficiency. Although the mean plasma levels were within the acceptable range for both vitamins, some 9 to 14% of individual subjects had folate plasma levels below normal. Fewer subjects had subnormal plasma vitamin B12 levels. Although mean values for dietary intake and plasma concentration of folate and vitamin B12 may indicate nutritional adequacy, a proportion of an older population may be at nutritional risk.

Aged↗