Functional hyperhomocysteinemia in healthy vegetarians: no association with advanced glycation end products, markers of protein oxidation, or lipid peroxidation after correction with vitamin B(12)

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 deficiency presenting as acute ataxia

A previously healthy 7-year-old Caucasian boy was hospitalised for evaluation of acute ataxia and failure to thrive, initially suspicious for an intracranial mass. Weight and body mass index were below the third percentile and he demonstrated loss of joint position and vibratory sense on examination. Laboratory studies revealed megaloblastic anaemia while an initial MRI of the brain showed no evidence of mass lesions or other abnormalities. A dietary history revealed the child subscribed to a restrictive vegan diet with little to no intake of animal products or other fortified foods. The child was diagnosed with presumed vitamin B12 deficiency and was treated with intramuscular B12 injections. Neurological symptoms resolved promptly within several days after starting therapy. This case underlines the importance of assessing nutritional status in the evaluation of neurological dysfunction in the pediatric patient.

Vitamin B-12 status is not associated with plasma homocysteine in parents and their preschool children: lacto-ovo, lacto, and ovo vegetarians and omnivores

OBJECTIVE

Vegetarians may be at risk of certain nutrient deficiencies, particularly vitamin B-12. Vitamin B-12 deficiency may increase plasma homocysteine concentration and thus may potentially increase the risk of cardiovascular disease in vegetarians. The purpose of this study was to assess and compare plasma homocysteine and vitamin B-12 status in vegetarian and omnivorous preschool children and their parents. In addition, the association between parents' and children's homocysteine and vitamin B-12 concentration was also examined.

METHODS

Fifty-six omnivores (28 preschool children and one of their parents), 34 lacto-ovo vegetarians (16 parents and 18 children), 5 ovo vegetarians (2 parents and 3 children), 1 lacto vegetarian parent, and 2 vegan parents were enrolled in this study. The mean age of preschool children was 5.1 +/- 1.3 years and that of their parent was 35.4 +/- 4.2 years. Nutrient intakes were recorded using 3-day dietary records. Fasting venous blood samples were obtained to measure serum creatinine, high-sensitivity C-reactive protein, hematological parameters, plasma homocysteine, serum folate, and vitamin B-12 concentrations.

RESULTS

There was no significant difference in dietary folate intake between vegetarian and omnivores within parent and child groups. The mean plasma homocysteine level of vegetarian parents and their children was in the physiological range, and they had slightly but not significantly higher plasma homocysteine levels than omnivores. Omnivorous parents and their children had significantly higher vitamin B-12 intake than vegetarian participants but similar serum vitamin B-12 concentrations. Plasma homocysteine concentration was significantly and negatively associated with only serum folate levels (beta = -0.15) and dietary vitamin B-12 intake (beta = -0.05) in the omnivorous parents after adjusting for age, gender, body mass index, and serum creatinine.

CONCLUSION

Vegetarian parents and their preschool children had a lower vitamin B-12 intake than omnivorous parents and their preschool children but similar plasma vitamin B-12 and homocysteine concentrations. Plasma homocysteine was not associated with serum vitamin B-12 levels in the parent, child, or pooled group.

No evidence for oxidative stress as a mechanism of action of hyperhomocysteinemia in humans

Oxidative stress has been suggested as one of the physiopathologic conditions underlying the association of total plasma homocysteine (p-tHcy) with cardiovascular disease (CVD), but this hypothesis has not been validated in human epidemiological studies. We measured plasma and erythrocyte antioxidant enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD), along with serum lipid-soluble antioxidants alpha-tocopherol, beta-carotene, lycopene and retinol, in a sample of 123 healthy elderly subjects (54 men, 69 women). Plasma malondialdehyde (p-MDA) was determined as a marker of lipid peroxidation, and p-tHcy was quantified by HPLC. No significant differences were found for p-MDA, GPx or SOD activities or serum antioxidant concentrations, in subjects with elevated p-tHcy (> or =15 micromol/l) as compared to those with lower plasma homocysteine. Hyperhomocysteinemia did not lead to increased risk of having the highest p-MDA values, in either sex. We found no evidence that p-tHcy was associated with lipid peroxidation in this elderly human sample. Our results do not support the view that hyperhomocysteinemia would induce an adaptive response of antioxidant systems, either. More epidemiologic and clinical research is needed to clarify whether homocysteine promotes atherosclerosis by means of an oxidative stress mechanism.

Probiotic lactobacilli: An innovative tool to correct the malabsorption syndrome of vegetarians?

Vegetarians may have subtle nutritional deficiencies which have been related to the occurrence of an unrecognized malabsorption syndrome. The excess phytate content in cereals, nuts, legumes and oilseeds which represent the mainstay of their food intake, seems to play a central role in the pathogenesis of this malabsorption syndrome as an inverse relationship has been shown to link the phytate content of the diet with the intestinal absorption of trace minerals and proteins. We postulate that manipulating the endogenous digestive microflora of subjects on a vegetarian diet through administering probiotic lactic bacteria would represent an innovative tool to counteract the occurrence of the malabsorption syndrome dependent on the high phytate content of their diet. Even though there are no data about the composition of endogenous digestive microflora in subjects on a vegetarian diet, we expect that probiotic lactobacilli can interact with or affect distinct yet interrelated components within the intestinal milieu, such as epithelial cells, enteric flora, and/or mucosal immune cells. This would ultimately translate into the correction of the unregulated mechanisms implicated in the altered intestinal absorption of trace metals and proteins commonly seen in vegetarians. Clinical experience with probiotic therapy of patients with inflammatory bowel disease fully agrees with this view. One additional point of interest is that probiotic lactobacilli, and other species of the endogenous digestive microflora as well, are an important source of the enzyme phytase which catalyses the release of phosphate from phytate and hydrolyses the complexes formed by phytate and metal ions or other cations, rendering them more soluble ultimately improving and facilitating their intestinal absorption. The regular intake of probiotic preparation, may represent a cheap and safe tool in order to convert a diet with a low potential for bioavailability of trace minerals and proteins, such as the vegetarian diet, into a diet with a high bioavailability potential. The benefit of such an approach would not be restricted to vegetarians.

Incorporation of a high level of vitamin B12 into a vegetable, kaiware daikon (Japanese radish sprout), by the absorption from its seeds

High level of vitamin B(12) was incorporated into kaiware daikon (Japanese radish sprout) by soaking its seeds in B(12) solutions. Vitamin B(12) amount incorporated into kaiware daikon increased up to 1.5 microg/g wet sprout with the soaking time of seeds in 0-200 microg/ml B(12) solution. Vitamin B(12) could be extracted more from the sample heated for a short time than from that of control without heat treatment.