Vitamin B-12 status in a macrobiotic community

Vegetarian diets and diets which restrict animal-source foods during childhood in high-income countries

Increasing numbers of populations in the West are restricting their intake of meat and other animal products for reasons relating to health or ethics; in many countries, these restrictions are already common for cultural, religious, or socio-economic reasons. By following their parent's diet, children are exposed in parallel. This narrative review aims at assessing current data regarding vegetarian diets in children from birth to 18 years of age, which include, by increasing degree of restriction, flexitarian, lacto-ovo-vegetarian, lacto-vegetarian, pescatarian, vegan and macrobiotic diets. The 202 references include 45 studies in children. The more restrictive the diet and the younger the child, the greater the risk of nutritional deficiency. Of particular concern are vitamin B12, iron, zinc, calcium, n-3 long-chain polyunsaturated fatty acids, and protein and energy intake, especially in pregnant and nursing women, infants and young children. Providing an adequate lacto-ovo-vegetarian diet is relatively easy, whereas the maintenance of more restrictive diets may be challenging. The benefits and risks of vegetarian diets in adults are relatively well documented, but data for children are scarce. Vegan and macrobiotic diets should be discouraged in pregnant and lactating mothers as well as in young children, who, otherwise, should pay careful attention to ensuring nutritional adequacy, blood testing and appropriate supplementation. The health consequences of a chosen diet should be discussed with parents and adolescents to ensure the best possible adherence to advice and prescriptions. There is a need for well conducted studies in children but also for better knowledge of nutrition in healthcare professionals.Abbreviations: ALA: α-linolenic acid; ARA: arachidonic acid; ASF: animal source foods; BMC: bone mineral content; BMD: bone mineral density; DHA: docosahexaenoic acid; DRV: dietary reference value; EPA: eicosapentaenoic acid; FLD: flexitarian diet; LA: linoleic acid; LC-PUFA: long-chain polyunsaturated fatty acids; LOVD: lacto-ovo-vegetarian diet; LVD: lacto-vegetarian diet; MAD: macrobiotic diet; OMD: omnivorous diet; PSF: plant-source foods; SFA: saturated fatty acids; VGD: vegetarian diets; VND: vegan diet.

Risk Assessment of Micronutrients Deficiency in Vegetarian or Vegan Children: Not So Obvious

Vegetarian diets have gained in popularity worldwide and therefore an increasing number of children may be exposed to the resulting nutritional consequences. Among them, the risk of micronutrient shortfall is particularly of concern. This narrative review aims to assess and discuss the relevance of micronutrient deficiency risk based on the available data. It mainly draws attention to iron, zinc, iodine, and vitamins B12 and D intake. Diets that are more restrictive in animal source foods, such as vegan diets, have a greater likelihood of nutritional deficiencies. However, the actual risk of micronutrient deficiency in vegetarian children is relatively difficult to assert based on the limitations of evidence due to the lack of well-designed studies. The risk of vitamin B12 deficiency must be considered in newborns from vegan or macrobiotic mothers and children with the most restrictive diet, as well as the risk of iron, zinc, and iodine deficiency, possibly by performing the appropriate tests. A lacto-ovo-vegetarian diet exposes a low risk if it uses a very varied diet with a sufficient intake of dairy products. Vegan and macrobiotic diets should be avoided during pregnancy and childhood. There is a need for education and nutrition guidance and the need for supplementation should be assessed individually.

Newborn screening for propionic, methylmalonic acidemia and vitamin B12 deficiency. Analysis of 588,793 newborns

OBJECTIVES

We present the results of our experience in the diagnosis and follow up of the positive cases for propionic, methylmalonic acidemias and cobalamin deficiencies (PA/MMA/MMAHC) since the Expanded Newborn Screening was implemented in Madrid Region.

METHODS

Dried blood samples were collected 48 h after birth. Amino acids and acylcarnitines were quantitated by MS/MS. Newborns with alterations were referred to the clinical centers for follow-up. Biochemical and molecular genetic studies for confirmation of a disease were performed.

RESULTS

In the period 2011-2020, 588,793 children were screened, being 953 of them were referred to clinical units for abnormal result (192 for elevated C3 levels). Among them, 88 were false positive cases, 85 maternal vitamin B12 deficiencies and 19 were confirmed to suffer an IEM (8 PA, 4 MMA, 7 MMAHC). Ten out 19 cases displayed symptoms before the NBS results (6 PA, 1 MMA, 3 MMAHC). C3, C16:1OH+C17 levels and C3/C2 and C3/Met ratios were higher in newborns with PA/MMA/MMAHC. Cases diagnosed with B12 deficiency had mean B12 levels of 187.6 ± 76.9 pg/mL and their mothers 213.7 ± 95.0; 5% of the mothers were vegetarian or had poor eating while 15% were diagnosed of pernicious anemia. Newborns and their mothers received treatment with B12 with different posology, normalizing their levels and the secondary alterations disappeared.

CONCLUSIONS

Elevated C3 are a frequent cause for abnormal result in newborn screening with a high rate of false positive cases. Presymptomatic diagnosis of most of PA and some MMA/MMAHC is difficult. Vitamin B12 deficiency secondary to maternal deprivation is frequent with an heterogenous clinical and biochemical spectrum.

Effects of Prolonged Whey Protein Supplementation and Resistance Training on Biomarkers of Vitamin B12 Status: A 1-Year Randomized Intervention in Healthy Older Adults (the CALM Study)

We investigated the effect of long-term whey supplementation on biomarkers of B12 status in healthy older adults subjected to different schemes of supplements and exercise. The total study population examined at baseline consisted of 167 healthy older adults (age ≥ 65 year) who were randomized to 1-y intervention with two daily supplements of (1) whey protein (3.1 µg B12/day) (WHEY-ALL), (2) collagen (1.3 µg B12/day) (COLL), or (3) maltodextrin (0.3 µg B12/day) (CARB). WHEY-ALL was comprised of three groups, who performed heavy resistance training (HRTW), light resistance training (LITW), or no training (WHEY). Dietary intake was assessed through 3-d dietary records. For the longitudinal part of the study, we included only the participants (n = 110), who met the criteria of ≥ 50% compliance to the nutritional intervention and ≥ 66% and ≥ 75% compliance to the heavy and light training, respectively. Fasting blood samples collected at baseline and 12 months and non-fasting samples collected at 6 and 18 months were examined for methylmalonic acid, B12 and holotranscobalamin. At baseline, the study population (n = 167) had an overall adequate dietary B12 intake of median (range) 5.3 (0.7-65) µg/day and median B12 biomarker values within reference intervals. The whey intervention (WHEY-ALL) caused an increase in B12 (P < 0.0001) and holotranscobalamin (P < 0.0001). In addition, methylmalonic acid decreased in the LITW group (P = 0.04). No change in B12 biomarkers was observed during the intervention with collagen or carbohydrate, and the training schedules induced no changes. In conclusion, longer-term daily whey intake increased plasma B12 and holotranscobalamin in older individuals. No effect of intervention with collagen or carbohydrate or different training regimes was observed. Interestingly, the biomarkers of B12 status appeared to be affected by fasting vs. non-fasting conditions during sample collection.

Infantile Tremor Syndrome or a Neurocutaneous Infantile B12 Deficiency (NIB) Syndrome?

OBJECTIVES

To prospectively study the clinical and developmental profile; hematological profile and the B-12 status using multiple parameters in children with Infantile tremor syndrome (ITS).

METHODS

In this observational study (NCT02762682) (July 2015 through December 2016) children (and their mothers) with a clinical diagnosis of ITS were evaluated clinically; and development was assessed by CAPUTE scales. A complete blood count (CBC); peripheral blood smear examination; markers of vitamin B12 status (serum B12, homocysteine, folate); acylcarnitines [using Tandem mass spectrometry (TMS)] and urine methylmalonic acid (MMA) [Gas chromatography mass spectrometry (GCMS)] were estimated. A control group of children and their mothers were sampled for comparison.

RESULTS

A total of 286 individuals were enrolled for this study. One-hundred-ten children with ITS were screened and 92 (20 with tremors; age 12.7 ± 5 mo, 61 boys) children and their mothers were enrolled. Fifty-one children and their mothers were enrolled as controls. The median clinical linguistic & auditory milestone-developmental quotient (CLAM-DQ) was 32 (IQR 20.6-45.5) and median cognitive adaptive test-developmental quotient (CAT-DQ) was 36.2 (IQR 18.7-49.0). All babies except 9 (ovo-veg) had vegetarian mothers. Head circumference below 2 SD (WHO standards) was seen in 84% and below 3 SD in 58%. The CBC findings were; Hb- 8.3 ± 1.6 g/dl, Thrombocytopenia-29 (32%), mean corpuscular volume (MCV)- 92.2 ± 13.4, MCV- more than 95 fL-38(42%), Red cell distribution width (RDW)- 21.6 ± 6.5, and macrocytes on peripheral smear in 68%. In 89 (97%) out of 92 children had laboratory features of deficient B12 status. Two-thirds of the mothers also had evidence of B12 deficiency.

CONCLUSIONS

ITS is, in all likelihood is a consequence of vitamin B12 defeciency. It has a significant impact on head growth and development of affected infants.

Associations of Circulating Methylmalonic Acid and Vitamin B-12 Biomarkers Are Modified by Vegan Dietary Pattern in Adult and Elderly Participants of the Adventist Health Study 2 Calibration Study

BACKGROUND

Elevated plasma methylmalonic acid (MMA) is a functional biomarker of vitamin B-12 status but limited information is available on its prevalence in US vegetarians.

OBJECTIVES

The study examines the prevalence of plasma MMA ≥0.27 µmol/L in those consuming vegetarian diets, its associations with vitamin B-12 intake and biomarkers, and the modifying effect of vegetarian patterns on these associations.

METHODS

In this cross-sectional study (n = 785), concentrations of MMA, vitamin B-12, holotranscobalamin (holoTC), and homocysteine (Hcy) were determined in participants of the calibration substudy of the Adventist Health Study 2 (AHS-2). Vitamin B-12 intake from food, fortified food, and supplements was assessed by six 24-h recalls. Regression models were used to estimate ORs of having high MMA as related to vitamin B-12 status biomarkers, vitamin B-12 intake, and dietary pattern.

RESULTS

The prevalence of low vitamin B-12 status defined by serum vitamin B-12 <148 pmol/L, holoTC <35 pmol/L, MMA ≥0.27 and ≥0.37 μmol/L, or Hcy ≥15 μmol/L, and the OR of having high MMA did not differ by dietary pattern, possibly due to intake from fortified food and supplements. Total daily vitamin B-12 intake in the second tertile range of 4.4-14.5 μg/d reduced the likelihood of elevated MMA by 69%; and a doubling of vitamin B-12 intake was associated with a 4.3% decrease in plasma MMA. The association between log plasma MMA and biomarkers was modified by diet, with the vegan pattern showing an ∼3-fold stronger association with log serum vitamin B-12 and Hcy than did the nonvegetarian pattern.

CONCLUSIONS

The prevalence of vitamin B-12 intake <2.0 μg/d was 15.2% in vegans, 10.6% in lacto-ovo-vegetarians, and 6.5% in nonvegetarians. Given the irreversible neurological consequences of vitamin B-12 inadequacy, the importance of regular supplemental vitamin B-12 intake in adult and elderly individuals is stressed.

Cyano-B12 or Whey Powder with Endogenous Hydroxo-B12 for Supplementation in B12 Deficient Lactovegetarians

Lactovegetarians (n = 35) with low vitamin B12 (B12) status were intervened for eight weeks capsules containing cyano-B12 (CN-B12), (2 × 2.8 µg/day), or equivalent doses of endogenous B12 (mainly hydroxo-B12 (HO-B12)) in whey powder. Blood samples were examined at baseline, every second week during the intervention, and two weeks post-intervention. The groups did not differ at baseline in [global median (min/max)] plasma B12 [112(61/185)] pmol/L, holotranscobalamin [20(4/99)] pmol/L, folate [13(11/16)], the metabolites total homocysteine [18(9/52)] µmol/L and methylmalonic acid [0.90(0.28/2.5)] µmol/L, and the combined indicator of B12 status (4cB12) [-1.7(-3.0/-0.33)]. Both supplements caused significant effects, though none of the biomarkers returned to normal values. Total plasma B12 showed a higher increase in the capsule group compared to the whey powder group (p = 0.02). However, the increase of plasma holotranscobalamin (p = 0.06) and the lowering of the metabolites (p > 0.07) were alike in both groups. Thereby, the high total plasma B12 in the capsule group was not mirrored in enhanced B12 metabolism, possibly because the B12 surplus was mainly accumulated on an "inert" carrier haptocorrin, considered to be of marginal importance for tissue delivery of B12. In conclusion, we demonstrate that administration of whey powder (HO-B12) or capsules (CN-B12) equivalent to 5.6 µg of B12 daily for eight weeks similarly improves B12 status but does not normalize it. We document that the results for plasma B12 should be interpreted with caution following administration of CN-B12, since the change is disproportionately high compared to the responses of complementary biomarkers.

Kinetic analysis of transcellular passage of the cobalamin-transcobalamin complex in Caco-2 monolayers

We suggest a novel kinetic approach to quantifying receptor–ligand interactions via the cellular transport and/or accumulation of the ligand. The system of cobalamin (Cbl, vitamin B12) transport was used as a model, because Cbl is an obligatory cofactor, taken up by animal cells with the help of a transport protein and a membrane receptor. Bovine transcobalamin (bTC) stimulated the cellular accumulation and transcytosis of radioactive [⁵⁷Co]Cbl in polarized monolayers of Caco-2 cells. The bovine protein was much more efficient than human TC. The transport was inhibited in a dose-dependent manner by the unlabeled bTC-Cbl complex, the ligand-free bTC, and the receptor-associated protein (RAP). This inhibition pattern implied the presence of a megalin-like receptor. Quantitative assessment of kinetic records by the suggested method revealed the apparent concentration of receptors in vitro (≈15 nM), as well as the dissociation constants of bTC–Cbl (K_d = 13 nM) and RAP (K_d = 1.3 nM). The data were used to estimate the effective luminal concentrations of TC-specific receptors in kidneys (3.8 µM) and intestine (50 nM), the tissues resembling polarized Caco-2 cells.

Bioavailability of Vitamin B12 from Dairy Products Using a Pig Model

The present study compares the bioavailability of vitamin B₁₂ (B₁₂) of dairy products or synthetic B₁₂, using the pig as an experimental model for humans. Eleven pigs were used in a cross-over design to assess the net portal drained viscera (PDV) flux of blood plasma B₁₂ after ingestion of tofu (TF; devoid of B₁₂), Swiss cheese (SC), Cheddar cheese (CC), yogurt (YG), and synthetic B₁₂ (TB₁₂; TF supplemented with cyanocobalamin), providing a total of 25 µg of B₁₂ each. PDV blood plasma flow for SC and CC were higher than for TF and TB₁₂ (p ≤ 0.04) whereas YG was higher than TF (p = 0.05). Porto-arterial difference of blood plasma B₁₂ concentrations were higher for CC and TB₁₂ than for TF and YG (p ≤ 0.04) but not different from SC (p ≥ 0.15). Net PDV flux of B₁₂ was only different from zero for CC. However, the net PDV flux of B₁₂ for CC was not different from SC or TB₁₂. Cumulative net PDV flux of B₁₂ for SC, TB₁₂, and CC were 2.9, 4.4, and 8.3 µg 23 h post-meal, corresponding to a bioavailability of 11.6%, 17.5%, and 33.0%, respectively. In conclusion, CC had the best bioavailability of B₁₂ among the tested dairy products or compared to synthetic B₁₂.

Foods and Supplements Associated with Vitamin B12 Biomarkers among Vegetarian and Non-Vegetarian Participants of the Adventist Health Study-2 (AHS-2) Calibration Study

To investigate the association between plasma concentration of vitamin B₁₂ and B₁₂ intake from supplements, fortified foods, and animal source foods among vegetarians and non-vegetarians, we conducted a cross-sectional analysis among 728 participants of the Adventist Health Study 2 (AHS-2) calibration study. The median age of participants was 58 years, 65.4% were female, and 50.3% were White. We used six 24 h dietary recalls to measure B₁₂ intake, serum vitamin B₁₂, and holotranscobalamin (holoTC) concentration. B₁₂ supplements had a significantly positive association with plasma B₁₂ among all subjects (p trend < 0.001), especially among vegans and lacto-ovo vegetarians (p trend < 0.001). Among non-users of B₁₂ supplements, B₁₂ intake from milk substitutes was significantly positively associated with holoTC (p trend < 0.004) and serum B12 (p trend < 0.030). In non-vegetarians, holoTC was significantly positively associated with B₁₂ intake from eggs, while serum B₁₂ was significantly positively associated with B₁₂ intake from milk in the upper tertile compared to the lower, and B₁₂ intake from meat in the middle compared to the lower tertile intake (p < 0.011). Supplements containing B₁₂ followed by B₁₂ intake from milk substitutes were significant contributors of plasma vitamin B₁₂ concentration.

Position paper on vegetarian diets from the working group of the Italian Society of Human Nutrition

BACKGROUND

Interest in vegetarian diets is growing in Italy and elsewhere, as government agencies and health/nutrition organizations are emphasizing that regular consumption of plant foods may provide health benefits and help prevent certain diseases.

METHODS AND RESULTS

We conducted a Pubmed search, up to September, 2015, for studies on key nutrients (proteins, vitamin B12, iron, zinc, calcium, vitamin D, and n-3 fatty acids) in vegetarian diets. From 295 eligible publications the following emerged: Vegetarians should be encouraged to supplement their diets with a reliable source of vitamin B12 (vitamin-fortified foods or supplements). Since the plant protein digestibility is lower than that of animal proteins it may be appropriate for vegetarians to consume more proteins than recommended for the general population. Vegetarians should also be encouraged to habitually consume good sources of calcium, iron and zinc - particularly vegetables that are low in oxalate and phytate (e.g. Brassicaceae), nuts and seeds, and calcium-rich mineral water. Calcium, iron, and zinc bioavailability can be improved by soaking, germination, and sour-dough leavening that lower the phytate content of pulses and cereals. Vegetarians can ensure good n-3 fatty acid status by habitually consuming good sources of a-linolenic acid (walnuts, flaxseeds, chia seeds, and their oils) and limiting linoleic acid intake (corn and sunflower oils).

CONCLUSIONS

Well-planned vegetarian diets that include a wide variety of plant foods, and a reliable source of vitamin B12, provide adequate nutrient intake. Government agencies and health/nutrition organizations should provide more educational resources to help Italians consume nutritionally adequate vegetarian diets.

Vitamin B12 among Vegetarians: Status, Assessment and Supplementation

Cobalamin is an essential molecule for humans. It acts as a cofactor in one-carbon transfers through methylation and molecular rearrangement. These functions take place in fatty acid, amino acid and nucleic acid metabolic pathways. The deficiency of vitamin B12 is clinically manifested in the blood and nervous system where the cobalamin plays a key role in cell replication and in fatty acid metabolism. Hypovitaminosis arises from inadequate absorption, from genetic defects that alter transport through the body, or from inadequate intake as a result of diet. With the growing adoption of vegetarian eating styles in Western countries, there is growing focus on whether diets that exclude animal foods are adequate. Since food availability in these countries is not a problem, and therefore plant foods are sufficiently adequate, the most delicate issue remains the contribution of cobalamin, which is poorly represented in plants. In this review, we will discuss the status of vitamin B12 among vegetarians, the diagnostic markers for the detection of cobalamin deficiency and appropriate sources for sufficient intake, through the description of the features and functions of vitamin B12 and its absorption mechanism.

Absorption and retention of free and milk protein-bound cyano- and hydroxocobalamins. An experimental study in rats

INTRODUCTION

Cobalamin/Vitamin B12 (Cbl) is an essential vitamin, supplied mainly as hydroxocobalamin (OHCbl) by animal products, including cows' milk. Cyanocobalamin (CNCbl) is the usual form in vitamin pills. The aim was to explore absorption and tissue accumulation of two Cbl forms, administered alone or bound to milk protein.

MATERIALS AND METHODS

We synthesized labeled OH[(57)Co]Cbl from commercially available CN[(57)Co]Cbl. Recombinant bovine transcobalamin (rbTC) was produced in yeast and skimmed milk obtained off the shelf. Male Wistar rats (250-300 g) received labeled Cbl by gastric gavage. First, we administered CN[(57)Co]Cbl, free or rbTC-bound (n = 15 in each group). Rats were sacrificed after two, 24, and 48 h. In the following studies, rats were sacrificed after 24 h. We compared absorption of free or rbTC-bound CN[(57)Co]Cbl added to cows' milk and analogous absorption of OH[(57)Co]Cbl, free or rbTC-bound, to absorption of free CN[(57)Co]Cbl, (n = 10 in each group). Blood, tissues, 24-h urine and feces were collected. Labeled Cbl was measured using a gamma counter. Results are expressed as percentage of administered dose.

RESULTS

Absorptions of CNCbl and OHCbl were neither influenced by rbTC-binding nor administration in milk. Absorption increased in the first 24 h with no further tissue accumulation during the subsequent 24 h. Accumulation of free CNCbl and (OHCbl) was 1.4, (4.1) (liver); 20.2, (16.4) (kidney); and 0.05, (0.02) (plasma)% 24 h after administration. Total organ accumulations were 21.6, (20.5)%. While total accumulations of CNCbl and OHCbl were equal, distributions between liver, kidney, and plasma showed significant differences (p < 0.0001; p = 0.01; p < 0.0001).

CONCLUSIONS

Cbl added to milk (spiked with rbTC) has high bioavailability matching that of free Cbl. OHCbl and CNCbl are absorbed equally well, but much more OHCbl accumulated in the liver. Benefits of oral supplementation with OHCbl compared to CNCbl should be investigated.

Vitamin B₁₂ and vegetarian diets

Vitamin B₁₂ is found almost exclusively in animal-based foods and is therefore a nutrient of potential concern for those following a vegetarian or vegan diet. Vegans, and anyone who significantly limits intake of animal-based foods, require vitamin B₁₂-fortified foods or supplements. Vitamin B₁₂ deficiency has several stages and may be present even if a person does not have anaemia. Anyone following a vegan or vegetarian diet should have their vitamin B₁₂ status regularly assessed to identify a potential problem. A useful process for assessing vitamin B₁₂ status in clinical practice is the combination of taking a diet history, testing serum vitamin B₁₂ level and testing homocysteine, holotranscobalamin II or methylmalonic acid serum levels. Pregnant and lactating vegan or vegetarian women should ensure an adequate intake of vitamin B₁₂ to provide for their developing baby. In people who can absorb vitamin B₁₂, small amounts (in line with the recommended dietary intake) and frequent (daily) doses appear to be more effective than infrequent large doses, including intramuscular injections. Fortification of a wider range of foods products with vitamin B₁₂, particularly foods commonly consumed by vegetarians, is likely to be beneficial, and the feasibility of this should be explored by relevant food authorities.

Critical levels of brain atrophy associated with homocysteine and cognitive decline

Few B-vitamin trials to lower homocysteine (Hcy) have reported evidence of beneficial effects on cognition in older adults with cognitive impairment or Alzheimer's disease. This article reviews the role of Hcy in cognitive decline. It also considers some reasons why meta-analyses have failed to find effects of B-vitamin treatment. Findings from the successful VITACOG trial are examined from a new perspective of critical levels of Hcy and brain atrophy that may impact on the efficacy of B-vitamin treatment. It appears that there is a critical level of brain shrinkage, possibly mediated by elevated Hcy, which when reached, results in cognitive decline, especially in episodic memory performance. Supplements, food sources, and effects of folic acid fortification are discussed in relation to B12 deficiency.

The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12: a review of literature

Individuals following vegetarian diets are at risk for developing vitamin B12 deficiency owing to suboptimal intake. As vitamin B12 is essential for the synthesis of nucleic acids, erythrocytes and in the maintenance of myelin, deficiency may result in a variety of symptoms. Some of these symptoms may be severe while others may be irreversible. The objective of this review was to assess vitamin B12 deficiency, based on reported serum vitamin B12, among individuals adhering to different types of vegetarian diets. A systematic literature search was carried out using multiple search engines including PubMed, Medline, CINAHL plus, ERIC, Nursing and Allied Health Collection and Nursing/Academic Edition. The inclusion criteria consisted of original studies that assessed serum vitamin B12, studies written in English, non-case studies and studies that reported actual percentages of vitamin B12 deficiency. Forty research studies were included. The deficiency prevalence among infants reached 45%. The deficiency among the children and adolescents ranged from 0 to 33.3%. Deficiency among pregnant women ranged from 17 to 39%, dependent on the trimester. Adults and elderly individuals had a deficiency range of 0-86.5%. Higher deficiency prevalence was reported in vegans than in other vegetarians. Thus, with few exceptions, the reviewed studies documented relatively high deficiency prevalence among vegetarians. Vegans who do not ingest vitamin B12 supplements were found to be at especially high risk. Vegetarians, especially vegans, should give strong consideration to the use of vitamin B12 supplements to ensure adequate vitamin B12 intake. Vegetarians, regardless of the type of vegetarian diet they adhere to, should be screened for vitamin B12 deficiency.

How prevalent is vitamin B(12) deficiency among vegetarians?

Vegetarians are at risk for vitamin B(12) (B12) deficiency due to suboptimal intake. The goal of the present literature review was to assess the rate of B12 depletion and deficiency among vegetarians and vegans. Using a PubMed search to identify relevant publications, 18 articles were found that reported B12 deficiency rates from studies that identified deficiency by measuring methylmalonic acid, holo-transcobalamin II, or both. The deficiency rates reported for specific populations were as follows: 62% among pregnant women, between 25% and almost 86% among children, 21-41% among adolescents, and 11-90% among the elderly. Higher rates of deficiency were reported among vegans compared with vegetarians and among individuals who had adhered to a vegetarian diet since birth compared with those who had adopted such a diet later in life. The main finding of this review is that vegetarians develop B12 depletion or deficiency regardless of demographic characteristics, place of residency, age, or type of vegetarian diet. Vegetarians should thus take preventive measures to ensure adequate intake of this vitamin, including regular consumption of supplements containing B12.

Cobalamin deficiency

Cobalamin (Cbl, vitamin B12) consists of a corrinoid structure with cobalt in the centre of the molecule. Neither humans nor animals are able to synthesize this vitamin. Foods of animal source are the only natural source of cobalamin in human diet. There are only two enzymatic reactions in mammalian cells that require cobalamin as cofactor. Methylcobolamin is a cofactor for methionine synthase. The enzyme methylmalonyl-CoA-mutase requires adenosylcobalamin as a cofactor. Therefore, serum concentrations of homocysteine (tHcy) and methylmalonic acid (MMA) will increase in cobalamin deficiency. The cobalamin absorption from diet is a complex process that involves different proteins: haptocorrin, intrinsic factor and transcobalamin (TC). Cobalamin that is bound to TC is called holotranscobalamin (holoTC) which is the metabolically active vitamin B12 fraction. HoloTC consists 6 and 20% of total cobalamin whereas 80% of total serum cobalamin is bound to another binding protein, haptocorrin. Cobalamin deficiency is common worldwide. Cobalamin malabsorption is common in elderly subjects which might explain low vitamin status. Subjects who ingest low amount of cobalamin like vegetarians develop vitamin deficiency. No single parameter can be used to diagnose cobalamin deficiency. Total serum cobalamin is neither sensitive nor it is specific for cobalamin deficiency. This might explain why many deficient subjects would be overlooked by utilizing total cobalamin as status marker. Concentration of holotranscobalamin (holoTC) in serum is an earlier marker that becomes decreased before total serum cobalamin. Concentrations of MMA and tHcy increase in blood of cobalamin deficient subjects. Despite limitations of these markers in patients with renal dysfunction, concentrations of MMA and tHcy are useful functional markers of cobalamin status. The combined use of holoTC and MMA assays may better indicate cobalamin status than either of them. Because Cbl deficiency is a risk factor for neurodegenerative diseases an early diagnosis of a low B12 status is required which should be followed by an effective treatment in order to prevent irreversible damages.

Assessment of the vitamin B12 status of pregnant women in Nigeria using plasma holotranscobalamin

Maternal vitamin B12 deficiency during pregnancy is an independent risk factor for neural tube defects and other neurological problems in infants. We determined the vitamin B12 status of 143 pregnant women in Nigeria representing all trimesters who presented to an antenatal clinic in Jos, Nigeria, using holotranscobalamin II levels (holoTCII), which is a measure of the vitamin B12 that is available for uptake into tissues. The holoTCII concentration ranged from 13 to 128 pmol/L. Using a cutoff of 40 pmol/L, 36% of the women were classified as vitamin B12-deficient. HoloTCII concentrations correlated negatively with plasma homocysteine levels (r = −0.24, P = 0.003) and positively with red blood cell folate concentrations (r = 0.28, P < 0.001). These data underscore the importance of supplementing pregnant women in Nigeria with vitamin B12 in order to ensure adequate vitamin B12 status and decrease the risk for neural tube defects.

Bioavailability of vitamin B₁₂ in cows' milk

The natural source of vitamin B₁₂ in human diets comes from animal products. For example, one glass (250 ml) of milk provides approximately 50 % of the RDA (2·4 μg/d). It was hypothesised that the provision of vitamin B₁₂ from milk is more efficiently absorbed than the synthetic form used in vitamin supplements. Pigs (n 10) were used as a model for intestinal absorption of vitamin B₁₂ in humans to compare the net fluxes of vitamin B₁₂ across the portal-drained viscera (PDV; an indicator of intestinal absorption) after ingestion of meals complemented with conventional and vitamin B₁₂-enriched (via injections to cows) milk (raw, pasteurised or microfiltrated) or with equivalent amounts of cyanocobalamin, the synthetic form used in supplements or unsupplemented. Net flux of vitamin B₁₂ across PDV after the ingestion of milk was positive, though not influenced by milk enrichment (P>0·3) or technological processes (P = 0·8) and was greater than after ingestion of equivalent amounts of cyanocobalamin (cyanocobalamin v. all milk, P ≤ 0·003). In fact, net fluxes of this vitamin were not different from 0 after either cyanocobalamin or the meal devoid of vitamin B₁₂ (unsupplemented v. cyanocobalamin, P = 0·7). The cumulative PDV fluxes during the 24 h following ingestion of meals complemented with milk varied from 5·5 to 6·8 μg. These values correspond to an efficiency of intestinal absorption of vitamin B₁₂ from milk varying between 8 and 10 %. Therefore, vitamin B₁₂, which is abundant in cows' milk, is also substantially more available than the most commonly used synthetic form of this vitamin.

Health aspects, nutrition and physical characteristics in matched samples of institutionalized vegetarian and non-vegetarian elderly (> 65yrs)

Background

Epidemiological studies indicate that a well balanced vegetarian diet offers several health benefits including a lower prevalence of prosperity diseases in vegetarians compared to omnivores. It was the purpose of the present study to compare nutritional and physical characteristics in matched samples of institutionalized vegetarian (V) and non-vegetarian (NV) elderly.

Methods

Twenty-two female and 7 male V (females: 84.1 ± 5.1yrs, males: 80.5 ± 7.5yrs) and 23 female and 7 male NV (females: 84.3 ± 5.0yrs, males: 80.6 ± 7.3yrs) participated. All subjects were over 65 years of age, and free of major disease or physical handicap. Dietary intake, blood profile, anthropometrics, and handgrip strength were determined.

Results

Mean daily energy intake was 6.8 ± 2.0MJ in V females, and 8.0 ± 1.4MJ in the NV females, only the V did not reach the recommended value of 7.8 MJ. Male V and NV had a mean daily energy intake of 8.7 ± 1.6MJ and 8.7 ± 1.2MJ respectively (RDI: 8.8 MJ). Mean carbohydrate intake was significantly below the RDI in NV only (female V: 47.8 ± 7.5E%, female NV: 43.3 ± 4.6E%, male V: 48.1 ± 6.4E%, male NV: 42.3 ± 3.6E%), while protein (female V: 17.3 ± 3.4E%, female NV: 19.5 ± 3.5E%, male V: 17.8 ± 3.4E%, male NV: 21.0 ± 2.0E%), and saturated fat intake (female V: 25.4 ± 8.2 g/day, female NV: 32.2 ± 6.9 g/day, male V: 31.4 ± 12.9 g/day, male NV: 33.4 ± 4.7 g/day) were too high in both V and NV. Mean micronutrient intakes met the RDI's in all 4 groups. Mean blood concentrations for vitamin B12, folic acid, iron, and calcium were normal in all 4 groups. Mean zinc blood serum was below the reference value in all groups, whereas estimated zinc intake was in agreement with the RDI. The mean blood cholesterol concentration was above the 200 mg/dl upper limit in the V group (213 ± 40 mg/dl) and below that limit in the NV (188 ± 33 mg/dl) group. Mean BMI was 26.1 ± 4.7 kg/m² in the female V, 26.8 ± 3.7 kg/m² in the female NV, 23.5 ± 3.7 kg/m² in the male V, and 25.2 ± 4.2 kg/m² in the male NV. V and NV scored below the reference values for the handgrip strength test.

Conclusions

Generally, our results show a similar profile for V and NV concerning dietary intake, blood values, and physical characteristics. Attention should be paid to the intake of mono- and disaccharides and saturated fats in the diet of both V and NV. This study indicates that a vegetarian lifestyle has no negative impact on the health status at older age.

Provision of a school snack is associated with vitamin B-12 status, linear growth, and morbidity in children from Bogota, Colombia

In 2004, Bogotá's Secretary of Education (SED) initiated a snack program in public primary schools. A midmorning food ration was provided free of charge to children to supplement 30 and 50% of their daily requirements of energy and iron, respectively. The purpose of this study, an observational investigation of 3202 children ages 5-12 y, was to examine whether the snack program improved children's nutritional and health status. We measured micronutrient levels (plasma ferritin and vitamin B-12, and erythrocyte folate), anthropometry, and reported morbidity during the first semester of the 2006 school year. After adjusting for socioeconomic status and other school interventions, children at schools receiving the snack (n = 1803) had greater increases in plasma vitamin B-12 (42 pmol/L; P < 0.0001) from baseline to 3 mo of follow-up than children at schools not receiving the snack (n = 1399). They also experienced a smaller decrease in height-for-age Z-scores than children who did not receive the snack (P = 0.001). Provision of the SED snack was associated with significantly fewer reported days with morbidity symptoms (e.g. cough with fever, diarrhea with vomiting), 44% fewer doctor visits (P = 0.02), and 23% fewer days of school absenteeism (P = 0.03). The snack was not related to ferritin or folate levels. In conclusion, provision of a school-administered snack was related to improved vitamin B-12 status and linear growth and decreased reported morbidity. Although provision of the snack was not related to BMI changes over a 4-mo period, snack components such as candy and sugar-sweetened beverages should be replaced with healthier options, as the rates of child overweight in Colombia are not negligible.

Dietary sources of vitamin B-12 and their association with plasma vitamin B-12 concentrations in the general population: the Hordaland Homocysteine Study

BACKGROUND

Limited information is available on the association between vitamin B-12 status and intake from different dietary sources.

OBJECTIVE

We investigated the relation of dietary intake of different food items with plasma vitamin B-12 concentrations in the general population.

DESIGN

A cross-sectional, population-based study of 5937 subjects in 2 age groups (47-49 and 71-74 y) from the Hordaland Homocysteine Study in Norway was conducted by using a food-frequency questionnaire and measurements of plasma vitamin B-12 concentrations.

RESULTS

A significant difference in plasma vitamin B-12 concentrations was observed with increasing total vitamin B-12 intake. A plateau was reached at an intake of approximately 10 microg/d. Plasma vitamin B-12 was associated with intakes of increasing amounts of vitamin B-12 from dairy products or fish (P for trend <0.001 for both) but not with intakes of vitamin B-12 from meat or eggs. For the same content of vitamin B-12, intake from dairy products led to the greatest increase in plasma vitamin B-12. Total intake of vitamin B-12, particularly from milk and fish, decreased the risk of vitamin B-12 concentrations <200 pmol/L and impaired vitamin B-12 function (vitamin B-12 <200 pmol/L and methylmalonic acid >0.27 micromol/L) in the total group and in 71-74-y-old subjects.

CONCLUSIONS

Dietary intake of dairy products and fish are significant contributors to plasma vitamin B-12 and may improve plasma vitamin B-12 status. Vitamin B-12 appears to be more bioavailable from dairy products; guidelines for improving vitamin B-12 status should take this into consideration.

Effect of vitamin B12 deficiency on neurodevelopment in infants: current knowledge and possible mechanisms

Severe vitamin B(12) deficiency produces a cluster of neurological symptoms in infants, including irritability, failure to thrive, apathy, anorexia, and developmental regression, which respond remarkably rapidly to supplementation. The underlying mechanisms may involve delayed myelination or demyelination of nerves; alteration in the S-adenosylmethionine:S-adenosylhomocysteine ratio; imbalance of neurotrophic and neurotoxic cytokines; and/or accumulation of lactate in brain cells. This review summarizes the current knowledge concerning infantile vitamin B(12) deficiency, including a pooled analysis of case studies of infants born to mothers with untreated pernicious anemia or a strict vegetarian lifestyle and a discussion of the mechanisms that may underlie the manifestations of deficiency.

Causes of Vitamin B12 and Folate Deficiency

This review describes current knowledge of the main causes of vitamin B12 and folate deficiency. The most common explanations for poor vitamin B12 status are a low dietary intake of the vitamin (i.e., a low intake of animal-source foods) and malabsorption. Although it has long been known that strict vegetarians (vegans) are at risk for vitamin B12 deficiency, evidence now indicates that low intakes of animal-source foods, such as occur in some lacto-ovo vegetarians and many less-industrialized countries, cause vitamin B12 depletion. Malabsorption of the vitamin is most commonly observed as food-bound cobalamin malabsorption due to gastric atrophy in the elderly, and probably as a result of Helicobacter pylori infection. There is growing evidence that gene polymorphisms in transcobalamins affect plasma vitamin B12 concentrations. The primary cause of folate deficiency is low intake of sources rich in the vitamin, such as legumes and green leafy vegetables, and the consumption of these foods may explain why folate status can be adequate in relatively poor populations. Other situations in which the risk of folate deficiency increases include lactation and alcoholism.

Homocysteine and cobalamin status in German vegans

OBJECTIVE

The study aimed to evaluate the homocysteine and cobalamin status of German vegans and determine whether the intake of very small amounts of foods of animal origin can improve this status.

DESIGN AND SETTING

Cross-sectional study, Germany.

SUBJECTS

The dietary and nutritional intakes of 131 vegans (73 women, 58 men; age range: 20.2-82.1 years) were evaluated using a general questionnaire and two food-frequency questionnaires.

RESULTS

The prevalence of inadequate cobalamin status in volunteers of the German Vegan Study was 28.2%, and that of hyperhomocysteinaemia, 38.1%. Moderate vegans were affected to a lesser extent than were strict vegans. Duration of veganism and cobalamin concentration were inversely correlated (Spearman's r=-0.175, P=0.047). Folate concentration and erythrocyte aspartic acid aminotransferase activity were not correlated with plasma homocysteine concentration, but duration of veganism correlated positively with homocysteine concentration (Spearman's r=0.319, P<0.001). Cobalamin and homocysteine concentrations were inversely correlated (when controlling for duration of veganism; r=-0.602, P<0.001).

CONCLUSION

Cobalamin status needs to be improved in order to minimise the risk of hyperhomocysteinaemia.

Low bone mineral density and bone mineral content are associated with low cobalamin status in adolescents

BACKGROUND

Cobalamin deficiency is prevalent in vegetarians and has been associated with increased risk of osteoporosis.

AIM OF THE STUDY

To examine the association between cobalamin status and bone mineral density in adolescents formerly fed a macrobiotic diet and in their counterparts.

METHODS

In this cross-sectional study bone mineral density (BMD) and bone mineral content (BMC) were determined by DEXA in 73 adolescents (9-15 y) who were fed a macrobiotic diet up to the age of 6 years followed by a lacto-(-ovo-) vegetarian or omnivorous diet. Data from 94 adolescents having consumed an omnivorous diet throughout their lives were used as controls. Serum concentrations of cobalamin, methylmalonic acid (MMA) and homocysteine were measured and calcium intake was assessed by questionnaire. Analysis of covariance (MANCOVA) was performed to calculate adjusted means for vitamin B12 and MMA for low and normal BMC and BMD groups.

RESULTS

Serum cobalamin concentrations were significantly lower (geometric mean (GM) 246 pmol/L vs. 469 pmol/L) and MMA concentrations were significantly higher (GM 0.27 micromol/L vs. 0.16 micromol/L) in the formerly macrobiotic-fed adolescents compared to their counterparts. In the total study population, after adjusting for height, weight, bone area, percent lean body mass, age, puberty and calcium intake, serum MMA was significantly higher in subjects with a low BMD (p = 0.0003) than in subjects with a normal BMD. Vitamin B12 was significantly lower in the group with low BMD (p = 0.0035) or BMC (p = 0.0038) than in the group with normal BMD or BMC. When analyses were restricted to the group of formerly macrobiotic-fed adolescents, MMA concentration remained higher in the low BMD group compared to the normal BMD group.

CONCLUSIONS

In adolescents, signs of an impaired cobalamin status, as judged by elevated concentrations of methylmalonic acid, were associated with low BMD. This was especially true in adolescents fed a macrobiotic diet during the first years of life, where cobalamin deficiency was more prominent.

Vitamin B12 deficiency as a worldwide problem

Pernicious anemia is a common cause of megaloblastic anemia throughout the world and especially in persons of European or African descent. Dietary deficiency of vitamin B12 due to vegetarianism is increasing and causes hyperhomocysteinemia. The breast-fed infant of a vitamin B12-deficient mother is at risk for severe developmental abnormalities, growth failure, and anemia. Elevated methylmalonic acid and/or total homocysteine are sensitive indicators of vitamin B12-deficient diets and correlate with clinical abnormalities. Dietary vitamin B12 deficiency is a severe problem in the Indian subcontinent, Mexico, Central and South America, and selected areas in Africa. Dietary vitamin B12 deficiency is not prevalent in Asia, except in vegetarians. Areas for research include intermittent vitamin B12 supplement dosing and better measurements of the bioavailability of B12 in fermented vegetarian foods and algae.

Dietary Pattern Is Associated with Homocysteine and B Vitamin Status in an Urban Chinese Population

To identify existing dietary patterns and examine associations between these patterns and plasma homocysteine and B vitamin concentrations in an urban Chinese population living in Beijing (n = 119), dietary information was collected with a food frequency questionnaire designed for this population. Plasma homocysteine and B vitamin concentrations were examined. Food group variables, expressed as percentages of total energy intake, were entered into cluster analysis to define three distinct dietary pattern groups. The prevalence of high homocysteine (>11 micromol/L for women and 12 micromol/L for men), was 31.9%; of low folate (<6.8 nmol/L), 36.2%; of low vitamin B-12 (<221 pmol/L), 36.9%; and of low vitamin B-6 (<30 nmol/L), 16.0%. The three dietary patterns derived were defined by relatively greater intake of 1) fruit and milk, 2) red meat and 3) refined cereals. More than 40% of subjects in the refined cereals group had high plasma homocysteine and low plasma folate concentrations, and 67% had low plasma vitamin B-12 concentrations. Those following the refined cereals pattern were 4 and 5.2 times more likely to have high homocysteine and low vitamin B-12 concentrations, respectively, relative to the fruit and milk dietary pattern group (P < 0.01), after adjustment for potential confounders. High intake of refined cereals was associated with low B vitamin and high homocysteine concentrations, whereas the pattern high in fruit and milk was associated with the lowest homocysteine. Dietary patterns appear to play an important role in the micronutrient and homocysteine status of these Chinese adults.

What do vegetarians in the United States eat?

BACKGROUND

Dietary patterns and nutrient intakes of vegetarians in a nationally representative survey have not been described.

OBJECTIVE

We sought to profile and compare nutrient and food consumption patterns of self-defined vegetarians and nonvegetarians in a representative sample of the US population.

DESIGN

Data from 13 313 participants (age: >/= 6 y) in the Continuing Survey of Food Intake by Individuals (CSFII) 1994-1996, 1998 were used to compare vegetarian and nonvegetarian dietary patterns. Self-defined vegetarians and nonvegetarians were those who responded positively or negatively, respectively, to the question "Do you consider yourself to be a vegetarian?" The vegetarian and nonvegetarian groups were further characterized as "no meat" or "ate meat" on the basis of a consumption cutoff of 10 g meat/d reported on 2 nonconsecutive 24-h dietary recalls.

RESULTS

Self-defined vegetarians whose recalls did not include meat represented 0.9% of this nationally representative sample of noninstitutionalized persons residing in the United States. Compared with nonvegetarians who ate meat, self-defined vegetarians aged >/= 20 y had lower body mass indexes regardless of whether they ate meat. Diets of self-defined vegetarians tended to be lower in total fat, saturated fat, and cholesterol and higher in fiber than did the diets of nonvegetarians who ate meat. Self-defined vegetarians whose recalls contained no meat consumed more grains, legumes, vegetables (green leafy and yellow), fruit, and wine, whereas those who ate meat consumed more fruit than did nonvegetarians.

CONCLUSION

Self-defined vegetarians may consume red meat, poultry, or fish. However, their dietary patterns are generally healthier than are those of nonvegetarians.

Vegetarian lifestyle and monitoring of vitamin B-12 status

Vegetarians are at risk to develop deficiencies of some essential nutrients, especially vitamin B-12 (cobalamin). Cobalamin occurs in substantial amounts only in foods derived from animals and is essential for one-carbon metabolism and cell division. Low nutritional intake of vitamin B-12 may lead to negative balance and, finally, to functional deficiency when tissue stores of vitamin B-12 are depleted. Early diagnosis of vitamin B-12 deficiency seems to be useful because irreversible neurological damages may be prevented by cobalamin substitution. The search for a specific and sensitive test to diagnose vitamin B-12 deficiency is ongoing. Serum vitamin B-12 measurement is a widely applied standard method. However, the test has poor predictive value. Optimal monitoring of cobalamin status in vegetarians should include the measurement of homocysteine (HCY), methylmalonic acid (MMA), and holotranscobalamin II. Vitamin B-12 deficiency can be divided into four stages. In stages I and II, indicated by a low plasma level of holotranscobalamin II, the plasma and cell stores become depleted. Stage III is characterized by increased levels of HCY and MMA in addition to lowered holotranscobalamin II. In stage IV, clinical signs become recognizable like macroovalocytosis, elevated MCV of erythrocytes or lowered haemoglobin. In our investigations, we have found stage III of vitamin B-12 deficiency in over 60% of vegetarians, thus underlining the importance of cobalamin monitoring in this dietary group.

The macrobiotic diet in cancer

Macrobiotics is one of the most popular alternative or complementary comprehensive lifestyle approaches to cancer. The centerpiece of macrobiotics is a predominantly vegetarian, whole-foods diet that has gained popularity because of remarkable case reports of individuals who attributed recoveries from cancers with poor prognoses to macrobiotics and the substantial evidence that the many dietary factors recommended by macrobiotics are associated with decreased cancer risk. Women consuming macrobiotic diets have modestly lower circulating estrogen levels, suggesting a lower risk of breast cancer. This may be due in part to the high phytoestrogen content of the macrobiotic diet. As with most aspects of diet in cancer therapy, there has been limited research evaluating the effectiveness of the macrobiotic diet in alleviating suffering or prolonging survival of cancer patients. The few studies have compared the experience of cancer patients who tried macrobiotics with expected survival rates or assembled series of cases that may justify more rigorous research. On the basis of available evidence and its similarity to dietary recommendations for chronic disease prevention, the macrobiotic diet probably carries a reduced cancer risk. However, at present, the empirical scientific basis for or against recommendations for use of macrobiotics for cancer therapy is limited. Any such recommendations are likely to reflect biases of the recommender. Because of its popularity and the compelling evidence that dietary factors are important in cancer etiology and survival, further research to clarify whether the macrobiotic diet or similar dietary patterns are effective in cancer prevention and treatment is warranted.

A critical assessment of some biomarker approaches linked with dietary intake

In this review many examples are given of the complexities involved in using some biomarkers in relation to assessing the effects of dietary exposure, when there is frequently a need to determine changes following long-term low level exposure to dietary components. These range from understanding why the biomarker might be valuable and how best it can be measured, to the pitfalls which can occur in the interpretation of data. Analytical technique is considered in relation to folate and selenium, and flavonoid and carotenoid species are used to illustrate how the metabolism of a compound may alter the validity or adequacy of a marker. Vitamin A is discussed in relation to the difficulties which can arise when there are several biomarkers that may be available to assess exposure to one nutrient. Vitamin B12 is discussed in relation to the dietary choices made by individuals. Possible interactions and the role of measuring total antioxidant capacity is considered in some detail. In contrast to most nutrients, there is a marked lack of biomarkers of either exposure or effect for most non-nutrients. The role of biological effect monitoring is considered for dietary contaminants, fumonisins and polyhalogenated aromatic hydrocarbons. Aflatoxins are discussed to exemplify food contaminants for which the biomarker approach has been extensively studied. Finally some compounds which are deliberately added to foods and some which appear as processing contaminants are each considered briefly in relation to the requirement for a biomarker of exposure to be developed.

Older men and women efficiently absorb vitamin B-12 from milk and fortified bread

Nothing is directly known about the bioavailability of vitamin B-12 from dairy products or fortified grain products. We directly studied vitamin B-12 absorption from water, milk and fortified bread in adult subjects using (58)Co-labeled vitamin B-12 and a whole body gamma-ray counter/spectrophotometer. Sixteen healthy men and women over the age of 60 y with normal serum levels of vitamin B-12 and normal basal gastric acid secretion were studied. (58)Co vitamin B-12 (0.25 microg) was administered in water, milk or fortified bread to each subject along with 185 kBq (5.0 microCi) (51)Cr as a stool marker. Whole body counting was performed 30 min after ingestion of the radioactive dose and at 7 and 14 d after dosing. Mean absorptions from water, milk and fortified bread were 55, 65 and 55%, respectively, and did not differ. The high body retention of the extrinsic vitamin B-12 label from milk and bread may warrant a greater use of such fortified products in the elderly to ensure vitamin B-12 adequacy.

Prolonged exclusive breast-feeding from vegan mother causing an acute onset of isolated methylmalonic aciduria due to a mild mutase deficiency

We describe a case of methylmalonic aciduria (MMA) occurred in a 22-month-old boy whose diet was exclusively based upon breast-feeding from a mother following a long-lasting strict vegetarian diet. Clinical picture showed a dramatic onset, with a profound drowsiness associated with a severe metabolic acidosis, hyperammonemia, macrocytic anemia, ketonuria, and massive methylmalonic aciduria without homocystinuria. Both symptoms and biochemical findings quickly improved thanks to prompt vitamin B(12)parenteral therapy. Biochemical and enzymatic findings allowed a diagnosis of mild mutase deficiency, which only and inadequate dietary B(12)contribution might have revealed. Our case highlights the risk of a prolonged strictly vegetarian diet of lactating mother for providing inadequate amounts of some nutrients to the breast-fed baby. Moreover, such a dietary behaviour could dramatically unmask otherwise clinically unapparent metabolic defects in the baby.

Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring study

BACKGROUND

Low vitamin B-12 status is prevalent among the elderly, but few studies have examined the association between vitamin B-12 status and intake.

OBJECTIVE

We hypothesized that vitamin B-12 concentrations vary according to intake source.

DESIGN

Plasma concentrations and dietary intakes were assessed cross-sectionally for 2999 subjects in the Framingham Offspring Study. The prevalence of vitamin B-12 concentrations <148, 185, and 258 pmol/L was examined by age group (26-49, 50-64, and 65-83 y), supplement use, and the following food intake sources: fortified breakfast cereal, dairy products, and meat.

RESULTS

Thirty-nine percent of subjects had plasma vitamin B-12 concentrations <258 pmol/L, 17% had concentrations <185 pmol/L, and 9% had concentrations <148 pmol/L, with little difference between age groups. Supplement users were significantly less likely than non-supplement-users to have concentrations <185 pmol/L (8% compared with 20%, respectively). Among non-supplement-users, there were significant differences between those who consumed fortified cereal >4 times/wk (12%) and those who consumed no fortified cereal (23%) and between those in the highest and those in the lowest tertile of dairy intake (13% compared with 24%, respectively), but no significant differences by meat tertile. Regression of plasma vitamin B-12 on log of intake, by source, yielded significant slopes for each contributor adjusted for the others. For the total group, b = 40.6 for vitamin B-12 from vitamin supplements. Among non-supplement-users, b = 56.4 for dairy products, 35.2 for cereal, and 16.7 for meat. Only the meat slope differed significantly from the others.

CONCLUSIONS

In contrast with previous reports, plasma vitamin B-12 concentrations were associated with vitamin B-12 intake. Use of supplements, fortified cereal, and milk appears to protect against lower concentrations. Further research is needed to investigate possible differences in bioavailability.

Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians

Dietary and nutritional status of individuals habitually consuming a vegan diet was evaluated by biochemical, hematologic, and immunologic measures in comparison with a nonvegetarian group. On the basis of 4-d dietary records, the intake of female and male vegans tended to be lower in fat, saturated fat, monounsaturated fat, and cholesterol and higher in dietary fiber than that of vegetarians. With computed food and supplement intakes, vegan diets provided significantly higher amounts of ascorbate, folate, magnesium, copper, and manganese in both female and male participants. The body mass index (BMI; in kg/m(2)) of the vegans was significantly lower than that of the nonvegetarians and 9 of the 25 vegans had a BMI <19. Serum ferritin concentrations were significantly lower in vegan men but iron and zinc status did not differ between the sexes. Mean serum vitamin B-12 and methylmalonic acid concentrations did not differ; however, 10 of the 25 vegans showed a vitamin B-12 deficit manifested by macrocytosis, circulating vitamin B-12 concentrations <150 pmol/L, or serum methylmalonic acid >376 nmol/L. Vegans had significantly lower leukocyte, lymphocyte, and platelet counts and lower concentrations of complement factor 3 and blood urea nitrogen but higher serum albumin concentrations. Vegans did not differ from nonvegetarians in functional immunocompetence assessed as mitogen stimulation or natural killer cell cytotoxic activity.

Risk of persistent cobalamin deficiency in adolescents fed a macrobiotic diet in early life

BACKGROUND

Cobalamin deficiency has been described in children consuming macrobiotic diets.

OBJECTIVE

We investigated whether moderate consumption of animal products is sufficient for achieving normal cobalamin function in 73 adolescents who had received a macrobiotic diet until 6 y of age and had then switched to a lactovegetarian, lactoovovegetarian, or omnivorous diet (macrobiotic adolescents).

DESIGN

Hematologic indexes and serum concentrations of methylmalonic acid (MMA), total homocysteine (tHcy), and folate were measured. Current consumption frequency of animal products and cobalamin intake from dairy products were assessed by questionnaire. Data from 94 age-matched adolescents who received an omnivorous diet from birth were used as a reference.

RESULTS

Serum cobalamin concentrations were significantly lower and concentrations of MMA and folate and mean corpuscular volume (MCV) were significantly higher in macrobiotic adolescents than in control adolescents: of macrobiotic adolescents, 21% had abnormal MMA concentrations (>0.41 micromol/L), 37% had abnormal cobalamin concentrations (<218 pmol/L), 10% had abnormal tHcy concentrations (> 12.8 micromol/L), and 15% had abnormal MCV (> 89 fL). In macrobiotic adolescents, dairy products (200 g milk or yogurt and 22 g cheese/d) supplied on average 0.95 microg cobalamin/d; additionally, these adolescents consumed fish, meat, or chicken 2-3 times/wk. In girls, meat consumption contributed more to cobalamin status than the consumption of dairy products, whereas in boys these food groups were equally important.

CONCLUSIONS

A substantial number of the formerly strict macrobiotic adolescents still had impaired cobalamin function. Thus, moderate consumption of animal products is not sufficient for restoring normal cobalamin status in subjects with inadequate cobalamin intake during the early years of life.

Cobalamin

Cobalamin (vitamin B12) is an essential nutrient derived exclusively from bacterial sources. It is an essential cofactor for three known enzymatic reactions. Untreated deficiency, caused by either the autoimmune disease pernicious anemia or nutritional lack, results in a macrocytic anemia and/or subacute combined degeneration of the spinal cord and is eventually fatal. Cobalamin in serum is bound to two proteins, transcobalamin and haptocorrin. The former is responsible for the essential delivery of cobalamin to most tissues. Inadequate tissue availability of cobalamin results in increased concentration of methylmalonic acid and homocyst(e)ine due to inhibition of methylmalonyl-CoA mutase and methionine synthase, respectively. Strict vegetarians have long been known to be at risk of cobalamin deficiency, which develops insidiously over many years. It is now clear that a significant number of the elderly and HIV-positive individuals are also at increased risk of deficiency. Any individual with reduced ability to split cobalamin from food-protein may also become deficient even though intrinsic factor is present. Diagnosis of cobalamin deficiency has frequently relied on total serum cobalamin and the Schilling test. Newer approaches such as analysis of methylmalonic acid, homocyst(e)ine, holotranscobalamin, anti-intrinsic factor antibodies, and serum gastrin may provide more cost-effective testing, as well as identify those with a covert deficiency.

Vegetarian diets and children

Although the general health and development of vegan and vegetarian children seem to be normal, there may be subtle differences compared with omnivores. They are at increased risk of iron deficiency, and impaired psychomotor development associated with iron deficiency has been reported in macrobiotic infants. Fortunately, this impairment is not permanent, and follow-up studies have reported higher-than-average intelligence quotients among older macrobiotic children. Several other hazards of vegetarian diets have been identified, including vitamin B12 deficiency, rickets, and a bulky diet that can restrict energy intake in the first few years of life; however, these pitfalls can be avoided easily, and children can be successfully reared on vegetarian diets.

Extensive laboratory assessment of nutritional status in fit, health-conscious, elderly people living in the Paris area. Research Group on Aging

OBJECTIVE

Nutritional status-related biological indexes were measured in fit, health-conscious elderly subjects in order to establish reference values for people over 70 years.

SUBJECTS

103 men and 90 women aged 70-89 years living freely in the Paris area volunteered to participate.

METHODS

Nutritional status was assessed by anthropometric and biochemical methods.

RESULTS

Serum protein and amino acid status was similar to that of young adults, with only 5.2% of the elderly subjects showing transthyretin concentrations < 0.20 g/L, as well as decreased essential amino acid levels. Iron status, assessed in terms of serum and erythrocyte ferritin levels, total iron binding capacity and erythrocyte protoporphyrin tended to be satisfactory, but iron depletion was detected in 8.8% of the subjects. Serum ferritin levels were elevated in 19.7% of the subjects. Folate and vitamin B12 status was satisfactory, while hypovitaminosis D was observed in 48.2% of cases.

CONCLUSION

Our findings suggest that, in aging uncomplicated by disease, nutritional status is similar to that in younger adults, although the range of values tended to be wider, with a higher risk of certain nutrient deficiencies.