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Biomedical subjects

L Langseth

Publications and source records attributed to L Langseth.

13 recordsLinked to original sources
PubMed1995

The health effects of vitamin C supplementation: a review.

A comprehensive review of the literature indicates that populations with long-term consumption of higher than RDA levels of vitamin C (> or = 60 mg/day) from foods and/or supplements have reduced risks of cancer at several sites, cardiovascular disease, and cataracts. The safety of higher than RDA intakes of vitamin C is confirmed in eight placebo-controlled, double-blind studies and six non-placebo clinical trials in which up to 10,000 mg of vitamin C was consumed daily for up to 3 years. There are no clinical data which suggest that vitamin C's enhancement of non-heme iron absorption in individuals with low iron status could be a critical factor in the possible increased risk of heterozygous hemochromatosis-related cardiovascular disease. In fact, the cumulative data do not confirm that iron status is related to risk of cardiovascular disease. Moreover, higher than RDA intakes of vitamin C have been associated with several indices of lowered cardiovascular disease risk including increases in HDL, and decreases in LDL oxidation, blood pressure and cardiovascular mortality.

Ascorbic Acid↗
PubMed1992

The new reference daily intakes: for better or for worse?

The introduction of the RDIs was well intentioned. However, there are scientific uncertainties and reasons for concerns about the proposed new nutrition standards. Adoption of the RDIs will inevitably lead to reduced intakes of critically important vitamins and minerals, will make it more difficult for members of nutritionally vulnerable groups to meet their nutrient needs, and will have undesirable effects on the health of the most needy by altering nutrition priorities and programs in this country. National nutrition standards remain with us for a long time. The U.S. RDAs have been in place for 18 years; any new standards need to be sound enough and safe enough to last as long. The proposed RDIs are clearly not of this caliber.

Eating↗
PubMed1989

Safety of vitamin A.

Vitamin A adequacy is discussed in terms of the recommended allowances appropriate for the needs of the majority of individuals. Deficiency can result in xerophthalmia and permanent blindness and in increased mortality rates among children. Toxicity has been associated with the overconsumption of vitamin A supplements. Acute hypervitaminosis A may occur after ingestion of greater than or equal to 500,000 IU (over 100 times the RDA) by adults or proportionately less by children. Symptoms are usually reversible on cessation of overdosing. Factors influencing chronic hypervitaminosis A include dosing regimen, physical form of the vitamin, general health status, dietary factors such as ethanol and protein intake, and interactions with vitamins C, D, E, and K. Both excess and deficiency of vitamin A in pregnant animals was shown to be teratogenic. In humans, congenital malformations associated with maternal over-use of high doses of vitamin A were reported but no cause-and-effect relationship has been established. Deficiency of the vitamin during pregnancy has also been associated with congenital abnormalities. Reported incidences of vitamin A toxicity are rare and have averaged fewer than 10 cases per year from 1976 to 1987.

Adolescent↗