Human vitamin and mineral requirements

(1973). Laboratory Tests for the Assessment of Nutritional Status. CRC Critical Reviews in Clinical Laboratory Sciences: Vol. 4, No. 3, pp. 215-340.

Laboratory Tests for the Assessment of Nutritional Status

Abstract Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for vitamin K. In this Opinion, the Panel considers vitamin K to comprise both phylloquinone and menaquinones. The Panel considers that none of the biomarkers of vitamin K intake or status is suitable by itself to derive DRVs for vitamin K. Several health outcomes possibly associated with vitamin K intake were also considered but data could not be used to establish DRVs. The Panel considers that average requirements and population reference intakes for vitamin K cannot be derived for adults, infants and children, and therefore sets adequate intakes (AIs). The Panel considers that available evidence on occurrence, absorption, function and content in the body or organs of menaquinones is insufficient, and, therefore, sets AIs for phylloquinone only. Having assessed additional evidence available since 1993 in particular related to biomarkers, intake data and the factorial approach, which all are associated with considerable uncertainties, the Panel maintains the reference value proposed by the Scientific Committee for Food (SCF) in 1993. An AI of 1 μg phylloquinone/kg body weight per day is set for all age and sex population groups. Considering the respective reference body weights, AIs for phylloquinone are set at 70 μg/day for all adults including pregnant and lactating women, at 10 μg/day for infants aged 7–11 months, and between 12 μg/day for children aged 1–3 years and 65 μg/day for children aged 15–17 years.

https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2017.4780

Dietary reference values for vitamin K.

The plasma pyridoxal-5'-phosphate (PLP) level of alcoholic subjects has been compared with that of non-alcoholic individuals in order to ascertain the incidence of abnormal vitamin B(6) metabolism in chronic alcohol abuse. 66 alcoholic subjects were selected on the basis that they did not exhibit abnormal liver function tests and hematologic findings. 35 of them had plasma PLP concentrations less than 5 ng/ml, the lowest value encountered in 94 control subjects, indicating a high incidence of deranged PLP metabolism in alcoholic patients even when hepatic and hematologic abnormalities are absent. The biochemical basis for the altered PLP metabolism in chronic alcohol abuse was examined. Low plasma PLP levels in alcoholics were not accompanied by decreased pyridoxal kinase and pyridoxine phosphate oxidase activities in erythrocytes. Further studies with erythrocytes demonstrated that the cellular content of PLP is determined not only by the activities of these PLP-synthesizing enzymes but also by the activity of a phosphate-sensitive, membrane-associated, neutral phosphatase, which hydrolyzes phosphorylated B(6) compounds.Acetaldehyde, but not ethanol, impaired the net formation of PLP from pyridoxal, pyridoxine, and pyridoxine phosphate by erythrocytes. However, when the B(6)-phosphate phosphatase activity was inhibited by 80 mM phosphate, this effect of acetaldehyde was abolished. By the use of broken cell preparations, it was possible to demonstrate directly that the action of acetaldehyde is mediated by the phosphatase, resulting in an acceleration of the degradation of the phosphorylated B(6) compounds in erythrocytes.

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Vitamin B6 Metabolism in Chronic Alcohol Abuse: PYRIDOXAL PHOSPHATE LEVELS IN PLASMA AND THE EFFECTS OF ACETALDEHYDE ON PYRIDOXAL PHOSPHATE SYNTHESIS AND DEGRADATION IN HUMAN ERYTHROCYTES

We describe optimized, ultraviolet spectrophotometric procedures for determination of erythrocyte transketolase, glutathione reductase, and aspartate aminotransferase activity, and their activation by their respective coenzymes--thiamine pyrophosphate, flavin-adenine dinucleotide, and pyridoxal-5-phosphate--as tests for vitamin B1, B2, and B6 deficiency. With these procedures we have investigated healthy subjects on normal and vitamin-supplemented diets, and a series of (mainly) alcoholic hospital in-patients. The enzyme procedures described have good precision and can be readily carried out in the routine laboratory. Abnormal transketolase activation correlated well with clinical evidence of vitamin B1 deficiency.

Arne Hamfelt

Papers

Age variation of vitamin B6 metabolism in man.

Pyridoxal phosphate and folic acid concentration in blood and erythrocyte aspartate aminotransferase activity during pregnancy

Pyridoxal phosphate concentration and aminotransferase activity in human blood cells.

A method of determining pyridoxal phosphate in blood by decarboxylation of L-tyrosine-14C (U).

Pyridoxal kinase activity in blood cells.