Consumption of vitamin D in fortified and natural foods and in vitamin preparations

Renal stones and coronary heart disease

The relationship between risk factors for coronary heart disease (CHD) and renal stone disease has been studied in a population of more than 2000 middle-aged men. The only positive association found was a slight increase in diastolic BP among stone formers and a higher stone prevalence in untreated hypertensives. Furthermore, the prevalence of a history of renal stones in male survivors of myocardial infarction (MI) was similar to that found in the population study. An investigation of the vitamin D intake by means of a dietary questionnaire revealed no differences between stone formers, healthy controls and MI survivors. Contrary to other reports, the present study indicates that the risk factor profile for CHD in stone formers is similar to that in the general population.

The relationship of adequate and excessive intake of vitamin D to health and disease

Vitamin D is required for intestinal calcium and phosphorus absorption, kidney functions, bone synthesis, and possible vital functions in several other target tissues. Active forms of vitamin D are generated by hydroxylations, first in the liver and second in the kidney. The requirement for vitamin D is normally met by its synthesis in the skin. Inadequate skin exposure to sunlight, dark-pigmented skin, and a northern geographical latitude make some individuals susceptible to a deficiency. In the United States, various foods are fortified with vitamin D to ensure that such deficiencies do not occur. As a result, most individuals consume and synthesize more vitamin D than they require. Vitamin D is a toxic compound, and excessive amounts can cause soft-tissue calcification. We have suggested a mechanism by which this calcification might occur. There is a narrow leeway between the amount required and that initiating tissue damage. As most individuals appear to be at risk of obtaining too much vitamin D rather than too little, we suggest that fortification of foods with vitamin D should be curtailed, preferably abolished, that excessive fortification of animal foods be reduced to the level required, and that the use of dietary supplements be restricted. Populations at risk could be monitored closely and counseled to prevent vitamin D deficiency.

Lighting for the elderly: a psychobiological approach to lighting

The present paper reviews the role of illumination in shaping the indoor environment of the elderly person. The approach is that lighting has a twofold impact on the individual. One is as a source of information about the environment, i.e., visual, and the other is photobiological through the skin or photoreceptor.

The visually lighted environment is reviewed, discussing first the physiological changes that occur during the aging process, then the effect of aging on visual performance, and finally the importance of qualitative factors in assessing the adequacy of an illuminated environment for the elderly. Special attention is given to application problems in lighting for the elderly, i.e., excessive brightness differences, discomfort glare, veiling reflections, and the importance of color and the spectral power distribution of the light source. The advantages of a full-spectrum light source which simulates natural sunlight for indoor illumination is discussed in light of recent research.

The biologically lighted environment is reviewed in terms of the potential role that indoor illumination can play in regulating important biochemical processes in the elderly population, i.e., neuroendocrine control, vitamin D3synthesis, immunologic mechanisms, and cardiovascular regulation.

Letter: Ischaemic heart disease, vitamins D and A, and magnesium

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Vitamin D and myocardial infarction

A detailed investigation was carried out into the consumption of vitamin D from different sources in patients who had suffered from myocardial infarction, angina pectoris, and degenerative joint diseases. Randomly selected controls of the same ages and sex were drawn from the Central Bureau of Statistics. The consumption was significantly higher in infarction patients. A daily intake of 30 mug may be the critical level. Student's t test for trend showed increasing probability of myocardial infarction with increasing intake of vitamin D, and more infarction patients than controls had a history of kidney stone. Long-term high consumption of vitamin D may be a precipitating cause of myocardial infarction.