Vitamin D and cardiovascular, renal, and brain damage in infancy and childhood

Use of Branded Food Composition Databases for the Exploitation of Food Fortification Practices: A Case Study on Vitamin D in the Slovenian Food Supply

Vitamin D deficiency is a worldwide public health concern, which can be addressed with voluntary or mandatory food fortification. The aim of this study was to determine if branded food composition databases can be used to investigate voluntary fortification practices. A case study was conducted using two nationally representative cross-sectional datasets of branded foods in Slovenia, collected in 2017 and 2020, and yearly sales data. Using food labeling data we investigated prevalence of fortification and average vitamin D content, while nutrient profiling was used to investigate overall nutritional quality of the foods. In both datasets, the highest prevalence of vitamin D fortification was observed in meal replacements (78% in 2017; 100% in 2020) and in margarine, corresponding to high market share. Other food categories commonly fortified with vitamin D are breakfast cereals (5% in 2017; 6% in 2020), yogurts and their imitates (5% in 2017; 4% in 2020), and baby foods (18% in both years). The highest declared average content of vitamin D was observed in margarine and foods for specific dietary use (7-8 μg/100g), followed by breakfast cereals (4 μg/100g), while the average content in other foods was below 2 μg/100g. Only minor differences were observed between 2017 and 2020. Major food-category differences were also observed in comparison of the overall nutritional quality of the fortified foods; higher overall nutritional quality was only observed in fortified margarine. Our study showed that branded food composition databases are extremely useful resources for the investigation and monitoring of fortification practices, particularly if sales data can also be used. In the absence of mandatory or recommended fortification in Slovenia, very few manufacturers decide to add vitamin D, and even when this is the case, such products are commonly niche foods with lower market shares. We observed exceptions in imported foods, which can be subject to fortification policies introduced in other countries.

Vitamin D supplementation during pregnancy: Improvements in birth outcomes and complications through direct genomic alteration

Pregnancy represents a time of rapid change, including dramatic shifts in vitamin D metabolism. Circulating concentrations of the active form of vitamin D-1,25(OH)2D skyrocket early in pregnancy to levels that would be toxic to a nonpregnant adult, signaling a decoupling of vitamin D from the classic endocrine calcium metabolic pathway, likely serving an immunomodulatory function in the mother and her developing fetus. In this review, we summarize the unique aspects of vitamin D metabolism and the data surrounding vitamin D requirements during this important period. Both observational and clinical trials are reviewed in the context of vitamin D's health effects during pregnancy that include preeclampsia, preterm birth, and later disease states such as asthma and multiple sclerosis. With enhanced knowledge about vitamin D's role as a preprohormone, it is clear that recommendations about supplementation must mirror what is clinically relevant and evidence-based. Future research that focuses on the critical period(s) leading up to conception and during pregnancy to correct deficiency or maintain optimal vitamin D status remains to be studied. In addition, what effects vitamin D has on genetic signatures that minimize the risk to the mother and her developing fetus have not been elucidated. Clearly, while there is much more research that needs to be performed, our understanding of vitamin D requirements during pregnancy has advanced significantly during the last few decades.

New insights into the vitamin D requirements during pregnancy

Pregnancy represents a dynamic period with physical and physiological changes in both the mother and her developing fetus. The dramatic 2–3 fold increase in the active hormone 1,25(OH)₂D concentrations during the early weeks of pregnancy despite minimal increased calcium demands during that time of gestation and which are sustained throughout pregnancy in both the mother and fetus suggests an immunomodulatory role in preventing fetal rejection by the mother. While there have been numerous observational studies that support the premise of vitamin D's role in maintaining maternal and fetal well-being, until recently, there have been few randomized clinical trials with vitamin D supplementation. One has to exhibit caution, however, even with RCTs, whose results can be problematic when analyzed on an intent-to-treat basis and when there is high non-adherence to protocol (as if often the case), thereby diluting the potential good or harm of a given treatment at higher doses. As such, a biomarker of a drug or in this case “vitamin” or pre-prohormone is better served. For these reasons, the effect of vitamin D therapies using the biomarker circulating 25(OH)D is a far better indicator of true “effect.” When pregnancy outcomes are analyzed using the biomarker 25(OH)D instead of treatment dose, there are notable differences in maternal and fetal outcomes across diverse racial/ethnic groups, with improved health in those women who attain a circulating 25(OH)D concentration of at least 100 nmol·L⁻¹ (40 ng·mL⁻¹). Because an important issue is the timing or initiation of vitamin D treatment/supplementation, and given the potential effect of vitamin D on placental gene expression and its effects on inflammation within the placenta, it appears crucial to start vitamin D treatment before placentation (and trophoblast invasion); however, this question remains unanswered. Additional work is needed to decipher the vitamin D requirements of pregnant women and the optimal timing of supplementation, taking into account a variety of lifestyles, body types, baseline vitamin D status, and maternal and fetal vitamin D receptor (VDR) and vitamin D binding protein (VDBP) genotypes. Determining the role of vitamin D in nonclassical, immune pathways continues to be a challenge that once answered will substantiate recommendations and public health policies.

Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Status Interact with Vitamin D and/or Calcium Status?

Although much is known about magnesium, its interactions with calcium and vitamin D are less well studied. Magnesium intake is low in populations who consume modern processed-food diets. Low magnesium intake is associated with chronic diseases of global concern [e.g., cardiovascular disease (CVD), type 2 diabetes, metabolic syndrome, and skeletal disorders], as is low vitamin D status. No simple, reliable biomarker for whole-body magnesium status is currently available, which makes clinical assessment and interpretation of human magnesium research difficult. Between 1977 and 2012, US calcium intakes increased at a rate 2-2.5 times that of magnesium intakes, resulting in a dietary calcium to magnesium intake ratio of >3.0. Calcium to magnesium ratios <1.7 and >2.8 can be detrimental, and optimal ratios may be ∼2.0. Background calcium to magnesium ratios can affect studies of either mineral alone. For example, US studies (background Ca:Mg >3.0) showed benefits of high dietary or supplemental magnesium for CVD, whereas similar Chinese studies (background Ca:Mg <1.7) showed increased risks of CVD. Oral vitamin D is widely recommended in US age-sex groups with low dietary magnesium. Magnesium is a cofactor for vitamin D biosynthesis, transport, and activation; and vitamin D and magnesium studies both showed associations with several of the same chronic diseases. Research on possible magnesium and vitamin D interactions in these human diseases is currently rare. Increasing calcium to magnesium intake ratios, coupled with calcium and vitamin D supplementation coincident with suboptimal magnesium intakes, may have unknown health implications. Interactions of low magnesium status with calcium and vitamin D, especially during supplementation, require further study.

Poisoning of dogs and cats by drugs intended for human use

One of the main causes of poisoning of small animals is exposure to drugs intended for human use. Poisoning may result from misuse by pet owners, off-label use of medicines or, more frequently, accidental ingestion of drugs that are improperly stored. This review focuses on classes of drugs intended for human use that are most commonly involved in the poisoning of small animals and provides an overview of poisoning episodes reported in the literature. To perform this review a comprehensive search of public databases (PubMed, Web of Science, Scopus, Google Scholar) using key search terms was conducted. Additionally, relevant textbooks and reference lists of articles pertaining to the topic were reviewed to locate additional related articles. Most published information on small animal poisoning by drugs intended for human use was from animal and human poison control centres or from single case reports. The dog was the species most frequently poisoned. The major drugs involved included analgesics (nonsteroidal anti-inflammatory drugs), antihistamines (H1-antihistamines), cardiovascular drugs (calcium channel blockers), central nervous system drugs (selective serotonin reuptake inhibitors, baclofen, benzodiazepines and zolpidem), gastrointestinal drugs (loperamide), nutritional supplements (vitamin D and iron salts) and respiratory drugs (β2-adrenergic receptor agonists).

Future directions in vitamin D and cardiovascular research

AIMS

Evidence is accumulating that vitamin D status may influence the risk of cardiovascular disease (CVD). Final confirmation for a causal relationship between vitamin D and CVD is however still lacking. The present viewpoint article outlines several future research directions to close this gap.

DATA SYNTHESIS

Future directions include the need of performing large randomised controlled supplementation trials with vitamin D in specific risk groups. In addition, large register sets of data on vitamin D supplementation can be used, provided that adequate statistical methods such as propensity score modelled analysis are applied. To better understand vitamin D-mediated effects on CVD risk, the routine measurement of circulating levels of the hormonal vitamin D form, 1,25-dihydroxyvitamin D, is also necessary, in addition to the determination of its precursor 25-hydroxyvitamin D. Further, genetic association studies may help in clarifying the contribution of vitamin D to the development of CVD. Finally, the interrelationship of vitamin D with physical activity should be considered when studying CVD risk.

CONCLUSIONS

Overall, it can be expected that the next 10-15 years will provide an increased clarity concerning the role of vitamin D in CVD.

Vitamin D and public health: an overview of recent research on common diseases and mortality in adulthood

OBJECTIVE

There is increasing interest in vitamin D and its possible health effects. The aims of the present overview are to summarise the research on common diseases for which there is substantial evidence on vitamin D, identify diseases where vitamin D may be beneficial and discuss the public health implications of these findings.

DESIGN

Literature search of PubMed for the years 2000 to 2010 to identify cohort studies with baseline measures of 25-hydroxyvitamin D (25(OH)D) and randomised controlled trials (RCT) of vitamin D supplementation in relation to fractures, colorectal cancer, CVD and all-cause mortality. Risk ratios of disease from comparisons between 25(OH)D quantiles in these studies were summarised using RevMan software version 5·1 (The Nordic Cochrane Centre, Copenhagen).

SETTING

Community-based samples recruited into cohort studies from many countries.

SUBJECTS

Older men and women, mostly above 50 years of age.

RESULTS

When comparing the lowest 25(OH)D category with the highest (or reference), the pooled risk ratio (95 % CI) was: 1·34 (1·13, 1·59) for fractures from nine studies; 1·59 (1·30, 1·95) for colorectal cancer from nine studies; 1·35 (1·17, 1·56) for CVD from twelve studies; and 1·42 (1·23, 1·63) for all-cause mortality from twelve studies.

CONCLUSIONS

Cohort studies show that baseline 25(OH)D levels predict increased risk of fractures, colorectal cancer, CVD and all-cause mortality. These associations are weak and could be explained by confounding variables such as obesity and physical activity. Because of their potential public health significance, RCT using vitamin D doses ≥50 μg/d are required to determine whether vitamin D protects against these diseases.

Does vitamin D make the world go 'round'?

Abstract Vitamin D has emerged from obscurity, and its effects on various organ systems throughout the body down to the cellular level are being discovered. What was once thought to be a simple hormone affecting only bone and calcium metabolism has shifted. We no longer see vitamin D as a "vitamin" important only in childhood, but as a complex hormone that is involved not only in calcium homeostasis but also in the integrity of the innate immune system. Vitamin D deficiency is linked to inflammatory and long-latency diseases such as multiple sclerosis, rheumatoid arthritis, tuberculosis, diabetes, and various cancers, to name a few. In this review, we trace how we came to view vitamin D and how that view led to one of the largest epidemics of nutrient deficiency beginning in the late 20(th) century. We then discuss the needs of vitamin D in the context of the breastfeeding mother and her infant and child, why breastfed infants are particularly at risk, and what to do about it.

Vitamin D requirement during pregnancy and lactation

The current recommended dietary requirement for vitamin D intake (200 IU/d) during pregnancy and lactation is based on little, if any, scientific evidence, and as a result is clinically irrelevant with respect to maintaining nutritional vitamin D status during these demanding human conditions. Current research has shown that the actual dietary requirement during pregnancy and lactation may actually be as high as 6000 IU/d. Current data on which these new recommendations could be based are presented.

“Over-The-Counter” Drug Toxicities in Companion Animals

A truly astonishing variety of "over-the-counter" drugs not taken under the auspices of a physician or veterinarian and not regulated by the Federal Drug Administration (FDA) are currently available to the American public. Many of these are widely advertised, readily available, remarkably inexpensive, and universally taken. Although most of the over-the-counter medications are fairly safe, the potential for toxic episodes exists due in large part simply on account of the amounts curious unsupervised animals may ingest. Another part of the problem is that since they are over the counter a large proportion of the public perceives them as totally harmless. In this article, we will investigate the most frequently seen non-prescription intoxications, their mechanism of action, clinical signs, diagnosis management, and prevention.

Elastic fibres and vascular structure in hypertension

Blood vessels are dynamic structures composed of cells and extracellular matrix (ECM), which are in continuous cross-talk with each other. Thus, cellular changes in phenotype or in proliferation/death rate affect ECM synthesis. In turn, ECM elements not only provide the structural framework for vascular cells, but they also modulate cellular function through specific receptors. These ECM-cell interactions, together with neurotransmitters, hormones and the mechanical forces imposed by the heart, modulate the structural organization of the vascular wall. It is not surprising that pathological states related to alterations in the nervous, humoral or haemodynamic environment-such as hypertension-are associated with vascular wall remodeling, which, in the end, is deleterious for cardiovascular function. However, the question remains whether these structural alterations are simply a consequence of the disease or if there are early cellular or ECM alterations-determined either genetically or by environmental factors-that can predispose to vascular remodeling independent of hypertension. Elastic fibres might be key elements in the pathophysiology of hypertensive vascular remodeling. In addition to the well known effects of hypertension on elastic fibre fatigue and accelerated degradation, leading to loss of arterial wall resilience, recent investigations have highlighted new roles for individual components of elastic fibres and their degradation products. These elements can act as signal transducers and regulate cellular proliferation, migration, phenotype, and ECM degradation. In this paper, we review current knowledge regarding components of elastic fibres and discuss their possible pathomechanistic associations with vascular structural abnormalities and with hypertension development or progression.

Risk analysis applied to food fortification

OBJECTIVE

To describe how a risk analysis can be applied to food fortification, with emphasis on voluntary fortification and intake levels that might exceed usual dietary levels.

DESIGN

Use of the risk analysis model as a frame to classify nutrients according to the risk of exceeding upper safe intake levels. Furthermore, to apply the model when discussing possible consequences of liberal fortification practices on eating behaviour and disease patterns.

SETTING

The discussion on food fortification presently going on internationally.

RESULTS

Micronutrients can be classified according to their safety margin, i.e. the size of the interval between the recommended intake and the upper safe level of intake. We suggest that nutrients with a small safety margin, i.e. for which the upper safe level is less than five times the recommended intake, be placed in a category A and should be handled with care (retinol, vitamin D, niacin, folate and all minerals). Category B comprises nutrients with an intermediate safety margin (vitamins E, B6, B12 and C), while nutrients that according to present knowledge are harmless even at 100 times the recommendation (vitamin K, thiamin, riboflavin, pantothenic acid and biotin) are categorised as C.

DISCUSSION

The risk analysis model is a useful tool when assessing the risk of both too low and excess intakes of single micronutrients, but can also be applied to analyse the consequences of fortification practices on eating behaviour and disease patterns. Liberal fortification regulations may, for example, distort the conception of what is healthy food, and drive consumption towards a more unhealthy diet, contributing to the plague of overweight and concomitant increased risk of degenerative diseases.

CONCLUSION

The impact of fortification practices on the total eating pattern of a population should become an integrated part of the discussions and regulations connected to the issue.

Serum 25-hydroxyvitamin D3 levels are elevated in South Indian patients with ischemic heart disease

Several lines of evidence point to a possible relationship between vitamin D and cardiovascular disease. Animal experiments and observational studies in humans suggest vitamin D to be arteriotoxic and an association of high intake of vitamin D with increased incidence of ischemic heart disease (IHD). The major source of vitamin D in adults is vitamin D synthesized in the skin through exposure to the sun. In tropical environment there is a possibility of high level of solar exposure and enhanced serum levels of vitamin D in the population. We explored the relation between serum level of 25-hydroxyvitamin D3 and IHD in a case-control study involving 143 patients with either angiographic evidence of coronary artery disease or patients with acute myocardial infarction and 70 controls, all men in the age group of 45-65 years. Fasting blood samples were collected, serum separated and serum levels of 25-hydroxyvitamin D3 was measured by protein binding radioligand assay. Serum levels of cholesterol, triglyceride, calcium, magnesium and inorganic phosphate were also determined. Prevalences of diabetes, hypertension and smoking history were noted. Statistical comparisons of variables between cases and controls were done using chi2-tests. Multivariate logistic regression analysis was done to examine the association of IHD with serum levels of 25-hydroxyvitamin D3 controlling for selected variables. Serum levels of 25-hydroxyvitamin D3, calcium, inorganic phosphate, total cholesterol, low density lipoprotein and triglycerides were elevated in a higher proportion of patients, compared to controls. Serum levels of 25-OH-D3 above 222.5 nmol/l (89 ng/ml) was observed in 59.4% of cases compared to 22.1% in controls (p < 0.001; unadjusted odds ratio (OR): 5.17; 95% confidence interval (CI): 2.62-10.21). When controlled for age and selected variables using the multivariate logistic regression, the adjusted OR relating elevated serum 25-hydroxyvitamin D3 levels (> or = 222.5 nmol/l, > or = 89 ng/ml) and IHD is 3.18 (95% CI: 1.31-7.73). Given the evidences for the arteriotoxicity of vitamin D, further investigations are warranted to probe whether the elevated serum levels of 25-hydroxyvitamin D3 observed in patients with IHD in a tropical environment has any pathogenic significance.

Vitamin D3 exacerbates intimal hyperplasia in balloon-injured arteries

Although a high dose of vitamin D3 is known to cause arterial calcification and degeneration, its effect on intimal hyperplasia has never been studied. The aim of this study was to examine the influence of a moderate supplement of vitamin D3 on intimal hyperplasia in the balloon-injured rat carotid artery. Forty-four rats had balloon injury to the carotid artery; 22 were given oral vitamin D3 supplementation (0.25 microgram kg-1 day-1). Animals were killed at 4 weeks and the carotid arteries were perfusion fixed and assessed morphometrically by means of computerized image analysis of transverse sections. Mean (s.e.m.) intimal area was significantly greater in the vitamin D3-treated animals than in controls: 0.92(0.05) versus 0.71(0.07) mm2 (P = 0.02). The area of the media of both injured and uninjured arteries was not influenced by vitamin D3 administration. A small dose of vitamin D3 resulted in significant exacerbation of intimal hyperplasia in this rat carotid artery model and raises the question of the role of dietary vitamin D3 in restenosis following vascular intervention.

Vitamin D increases expression of the tyrosine hydroxylase gene in adrenal medullary cells

We examined expression of the 1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3] receptors in chromaffin cells of the adrenal medulla and the effects of 1,25(OH)2 D3 on expression of the tyrosine hydroxylase (TH) gene. Accumulation of 1,25(OH)2 D3 in the nuclei of adrenal medullary cells, but not in the adrenal cortex, was observed in mice intravenously injected with radioactively labeled hormone. 1,25(OH)2 D3 produced concentration-dependent increases in the TH mRNA levels in cultured bovine adrenal medullary cells (BAMC). The maximal increases (2-3-fold) occurred at 10(-8) M 1,25(OH)2 D3. Combined treatment with 1,25(OH)2 D3 and 20 microM nicotine had no additive effect on TH mRNA levels suggesting that transsynaptic (nicotinic) and vitamin D (hormonal) stimulation of TH gene expression are mediated through converging mechanisms. Induction of TH mRNA by 1,25(OH)2 D3 was not affected by calcium antagonist TMB-8. By increasing expression of the rate limiting enzyme in the catecholamine biosynthetic pathway, 1,25-(OH)2 D3 may participate in the regulation of catecholamine production in adrenal chromaffin cells. This regulation provides mechanisms through which 1,25(OH)2 D3 may control response and adaptation to stress.

The role of vitamin D3 in the aetiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) have traditionally been attributed to atherosclerosis, although there is increasing epidemiological, biochemical and genetic evidence that aneurysmal arterial disease is different from occlusive atherosclerosis. One of the most consistent biochemical findings in the aneurysmal aorta is a significant reduction in elastin protein; the cause, for this remains unclear. There is in vitro evidence that vitamin D3 (1,25 dihydrocholecalciferol) inhibits the production of elastin by smooth muscle cells. On the basis of this observation and the possibility that some subjects may be exposed to excess vitamin D3, the hypothesis that vitamin D3 may be a previously unrecognized aetiological factor in the pathogenesis of AAA is developed.

Hypothesis: etiology of atherosclerosis and osteoporosis: are imbalances in the calciferol endocrine system implicated?

Atherosclerosis and osteoporosis are currently considered unrelated diseases. Osteoporosis involves bone calcium (Ca) loss and predominantly affects females after menopause. Atherosclerosis is an illness predominantly affecting males, and is primarily characterized by abnormal lipid metabolism. However, pathological calcification of the arterial wall is an underlying feature of atherosclerosis. Ca homeostasis is thus important in atherosclerosis as well as in osteoporosis. Men also develop osteoporosis although at a later age than women, and, as osteoporosis progresses in women, there is an accompanying calcification of arteries leading to increased incidence of atherosclerosis in aging women. Thus, during old age, both atherosclerosis and osteoporosis are prevalent in both males and females. The dramatic increase in atherosclerosis among women as they develop osteoporosis suggests that the two illnesses may be more closely related than previously realized. The use of vitamin D as a food supplement coincides with epidemic onsets of atherosclerosis and osteoporosis, and excess vitamin D induces both conditions in humans and laboratory animals. These observations suggest a role for chronic vitamin D excess in the etiology of the two illnesses. Magnesium (Mg) deficiency, nicotine, and high dietary cholesterol are contributing factors that accentuate adverse effects of vitamin D.

Effects of a dietary magnesium deficiency and excess vitamin D3 on swine coronary arteries

The effect of a moderate magnesium (Mg) deficiency on coronary arteries of 61 swine, fed various levels of vitamin D3, was studied by light and electron microscopy. The effect of subnormal Mg intake on vitamin D3-induced intimal lesions of the arteries showed a trend towards increased damage. The degree of cell degeneration and intimal thickening, which was induced by high vitamin D intakes, was as great in swine whose diet was low in Mg and moderately high in vitamin D as it was in those on twice as much vitamin D. Also, the degree of arterial calcification was intensified by inadequate Mg intake at the two higher vitamin D intakes. Present findings indicate that suboptimal dietary Mg, in combination with an excess of vitamin D, has an additive effect in the initiation of ultrastructural changes in the coronary arteries. Extension of the study is indicated to ascertain the extent to which further reduction of Mg intake can potentiate vitamin-D-induced coronary lesions.

Steroid hormones and the cardiovascular system: direct actions of estradiol, progesterone, testosterone, gluco- and mineralcorticoids, and soltriol [vitamin D] on central nervous regulatory and peripheral tissues

Knowledge of steroid hormone sites of action and related effects in cardiovascular and neural regulatory tissues is reviewed. Evidence for nuclear receptor sites is derived mainly from autoradiographic studies with relatively intact tissues and some biochemical studies with tissue homogenates. In the heart and in the walls of blood vessels, estradiol, dihydrotestosterone, corticosterone, aldosterone, dexamethasone, and soltriol (vitamin D) show nuclear binding. In the brain and spinal cord, neuronal regions associated with cardiovascular regulation contain nuclear receptors in specific patterns for each steroid hormones, including progesterone and soltriol. These data indicate that all steroid hormones exert direct actions on the cardiovascular system at its different levels of organization, thus enabling adjustment to the changing demands during reproduction (gonadal steroids), stress (adrenal steroids), and solar seasons (vitamin D-soltriol).

Coronary heart disease: the significance of coronary pathology in infancy and the role of mitogens such as vitamin D

Intimal hyperplasia, damage to the internal elastic lamina, and proliferation of medial smooth muscle cells characterise the early response of an artery to damage. These changes are seen in the coronary arteries of the transplanted human heart, and are commonly seen in "normal" infants. Lipid incursion occurs only later, and the end-result is atheroma. These lesions of infancy are probably pathologic rather than physiologic, and are the precursors of later coronary heart disease. The early intimal and medial changes may be immune-engendered, encouraged by mitogens such as Vitamin D, and evolve in infancy as an aberration of the normal mechanisms controlling cellular proliferation.

1,25-Dihydroxyvitamin D3-induced alterations of lipid metabolism in human monocyte-macrophages

An in vivo atherogenic role of dietary vitamin D has been postulated. To address this hypothesis we sought to determine the in vitro effects of its active circulating metabolite, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on lipid metabolism in human monocyte-derived macrophages. When cultured 6 days in the presence of 10(-8) M 1,25(OH)2D3 monocyte-macrophages accumulated significantly more triglycerides than control cells: 987.6 +/- 26.8 vs. 779.3 +/- 24.1 micrograms/mg protein (P less than 0.001). Triglyceride accumulation was associated with a hormone-induced stimulation of triglyceride synthesis as determined by [3H]oleate incorporation into cellular triglycerides. The effect of the hormone was significant after 24 h and dose dependent [10(-11) to 10(-8) M 1,25(OH)2D3]. It was specific since 10(-7) M 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 did not stimulate triglyceride synthesis, and its magnitude decreased from 1 to 9 days of culture. 1,25(OH)2D3 (10(-8) M) modified the cholesteryl ester metabolism of monocyte-macrophages only in the presence of acetylated low-density lipoproteins (50 micrograms/ml); it induced a significant increase of cellular cholesteryl ester content (21.9 +/- 1.1 vs. 11.7 +/- 1.7 micrograms/mg protein; P less than 0.001) and of esterification rate of cholesterol measured by [3H]oleate incorporation into cellular cholesteryl esters (17.2 +/- 0.9 vs. 6.5 +/- 0.3 nmol.mg protein-1.24 h-1; P less than 0.001) by comparison with control cells. These results show that 1,25(OH)2D3 alters in vitro lipid metabolism in the human monocyte-macrophage and suggest a new in vivo role for the hormone.

Cardiovascular consequences of magnesium deficiency and loss: pathogenesis, prevalence and manifestations--magnesium and chloride loss in refractory potassium repletion

Dietary magnesium (Mg) deficiency is more prevalent than generally suspected and can cause cardiovascular lesions leading to disease at all stages of life. The average American diet is deficient in Mg, especially in the young, in alcoholic persons, and in those under stress or with diseases or receiving certain drug therapies, who have increased Mg needs. Otherwise normal, Mg-deficient diets cause arterial and myocardial lesions in all animals studied, and diets that are atherogenic, thrombogenic and cardiovasopathic, as well as Mg-deficient, intensify the cardiovascular lesions, whereas Mg supplementation prevents them. Diuretics and digitalis can intensify an underlying Mg deficiency, leading to cardiac arrhythmias that are refractory unless Mg is added to the regimen. Potassium (K) depletion in diuretic-treated hypertensive patients has been linked to an increased incidence of ventricular ectopy and sudden death. K supplementation alone is not the answer. Mg has been found to be necessary to intracellular K repletion in these patients. Because patients with congestive heart failure and others receiving diuretic therapy are also prone to chloride loss leading to metabolic alkalosis that also interferes with K repletion, the addition of Mg and chloride supplements in addition to the K seems prudent.

1,25-Dihydroxyvitamin D3 binds specifically to rat vascular smooth muscle cells and stimulates their proliferation in vitro

Cultured vascular smooth muscle cells (VSMC) derived from rat aorta were found to contain a specific receptor for 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Its Kd (5.0 x 10(-11) M) and capacity (22.9 fmol/mg of cytosol protein) for 1,25-(OH)2D3, its sedimentation coefficient on a sucrose density gradient (3.2 S), its relative affinities for various vitamin D3 metabolites [1,25-(OH)2D3 greater than 25-hydroxyvitamin D3 greater than 24,25-dihydroxyvitamin D3 greater than vitamin D3] and its affinity for DNA-cellulose were similar to those reported for the 1,25-(OH)2D3 receptor in other tissues. 1,25-(OH)2D3 at concentrations of more than 10(-10) M caused dose-dependent enhancement of the proliferation of VSMC in DMEM with 10% FCS. 25-Hydroxyvitamin D3 stimulated the proliferation of VSMC only at its highest concentration tested (10(-6) M). These data show that 1,25-(OH)2D3 stimulates the proliferation of VSMC after its binding to a cytoplasmic receptor of the cells in vitro, and support the possibility that VSMC are target cells of the hormone.

Elevated plasma 1,25-dihydroxyvitamin D concentrations in infants with hypercalcemia and an elfin facies

We measured plasma concentrations of 1,25-dihydroxyvitamin D (1,25-(OH)2D) in the course of a 6-to-37-month survey of four children with hypercalcemia and an elfin facies (Williams syndrome). Levels of 1,25-(OH)2D were elevated (160 to 470 pg per milliliter) during the hypercalcemic phase of the disease, when the children were five to nine months old, and they decreased thereafter. Plasma 1,25 (OH)2D levels were higher than those found in three children (16 to 60 months old) with the elfin facies syndrome and no hypercalcemia (42 to 71 pg per milliliter) and eight children (1 to 36 months old) with hypercalcemia and no dysmorphy (12 to 140 pg per milliliter), including two children with vitamin D intoxication. Hypercalcemia in the three children with elfin facies was controlled by a low-calcium diet. Serum calcium levels fell to the normal range, and plasma 1,25-(OH)2D levels were normal for age (18 to 105 pg per milliliter) at 14 to 47 months of age, even after appropriate therapy had been discontinued. These observations suggest that hypercalcemia may be the consequence of abnormal synthesis or degradation of 1,25-(OH)2D in children with the elfin facies syndrome.

Administration of 1,25-dihydroxyvitamin D3 results in the elevation of hippocampal seizure threshold levels in rats

Electrical stimulation of the dorsal hippocampal formation of the rat was employed to determine the effect of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), the hormonal form of vitamin D, on induced seizure thresholds. Stereotaxic injection of 100 micrograms or 50 micrograms 1,25-dihydroxyvitamin D3 in 2 microliter propylene glycol into the hippocampus resulted in a significant elevation in seizure threshold in all animals treated. 1,25-dihydroxyvitamin D3-induced increases were noted within 5-10 min and lasted at least 120-180 min after injection when the experiments were terminated. Intravenous injection of 1,25-(OH)2D3 also resulted in a significant elevation of seizure threshold; however, the increase was transient, lasting only 30 min. This effect was specific since 200 micrograms vitamin D3 or 200 micrograms 25-hydroxyvitamin D3 (25-(OH)D3), injected into the hippocampus, had no effect on seizure threshold levels. This investigation represents the first direct demonstration of a role for 1,25-(OH)2D3 in the regulation of seizure activity and suggests, along with the previously demonstrated presence of immunoreactive vitamin D-dependent calcium binding protein and receptors for 1,25-dihydroxyvitamin D3 in the brain, that the vitamin D endocrine system may play a significant role in the physiological mechanisms underlying convulsive disorders.

Safety of megavitamin therapy

Carbon compounds that are needed in small amounts in the diet because they are not made in the body of vertebrates are defined as vitamins. Excluded from this definition are vitamins D, K, and niacin which can be synthesized by the organism or, as in the case of vitamin K, by the host's intestinal bacteria. Lack of such vitamins can result in characteristic deficiency diseases. The therapeutic use of such compounds (megavitamin intake) is based on the spectacular effect of vitamins on deficiency diseases; however, evidence that the ingestion of large amounts of vitamins beyond the "Recommended Daily Allowances" (RDA) is beneficial is not within the basic concept of nutrition. Vitamins, like many substances, may be toxic when taken in large quantities, especially the fat-soluble vitamins, and the concept of "more is better" is a common misconception. Vitamin supplements can be suggested only in the unusual cases of patients having inadequate intake, disturbed absorption (genetic or otherwise), or increased tissue requirements. A well-balanced diet that includes a wide variety of foods from each of the four food groups is adequate for the supply of vitamins, as well as other nutrients, in healthy people. This paper will review some of the recent findings regarding vitamin toxicity and the mechanisms of toxicity.

Food faddism in pediatrics

An understanding of the nutritional requirements of healthy, growing infants and children is required to guide parents in appropriate feeding practices which are consistent with their chosen life styles. Among the several prevalent types of food faddism are some that are not harmful or can beneficial, such as breast-feeding, others than can be of long-term benefit but that have limitations in infants and children, and others that can affect infants and children adversely. Those wishing to feed their children unconventional diets should have such diets carefully evaluated to avoid deficiencies of essential nutrients.

Laissez-faire in research

These were informal remarks in an after-dinner speech about nutritional and pediatric research as it was initiated 50 years ago when the Cincinnati Children's Hospital Research Foundation was opened. Although from the beginning there were "divisions" in the institute, the success of the organization was due to cooperation rather than division and to the freedom of the investigators to alter their directions according to their change of interests and to changes of needs and opportunities. A plea is made to let capable investigators choose their topics and their methods of research; they are most likely to have success when they are left alone and free of outside pressures.

Modification of cell membrane composition by dietary lipids and its implications for atherosclerosis

Dietary lipids can modify the properties of cell membranes, including membrane fluidity and membrane permeability. The saturation and isomerization of dietary fatty acids may affect the pattern of fatty acids acylated to glycerol in phospholipids. Oxidized sterols may affect membrane properties directly by their insertion in the membrane or indirectly through their effects on lipid metabolism. The flow of calcium and other nutrients into the cells appears to be a major property affected by those changes in lipid composition of membranes and may be important in the onset of atherosclerosis. The factors that alter the character of the lipids in cell membranes should receive increased study in both in vitro and in vivo systems to clarify their role in diseases processes.

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.

A new measure of growth efficiency: skull base height

Skull base height increases significantly with better nutrition and health conditions, as seen in comparing 163 nineteenth to twentieth century dissecting-room skeletons (Terry Collection) with 237 modern American middle-class adults (forensic and willed skeletons). The increase parallels the change in pelvic inlet depth index, known to respond sensitively to nutrition, and in stature, and is over six times greater than the general skull size change. Skull base height (porion-basion) is easy to measure with depth gauge and sliding caliper, or by subtraction, and is in adult a sensitive indicator of childhood growth stress.

Brain target sites for 1,25-dihydroxyvitamin D3

Autoradiographic studies with 3H-labeled 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] demonstrate, in certain neurons of rat forebrain, hindbrain, and spinal cord, a nuclear retention and concentration of radioactivity, which can be prevented by treatment with 1,25(OH)2D3, but not with 25-hydroxyvitamin D3. These results indicate the presence of brain receptors in addition to pituitary receptors for 1,25(OH)2D3 and suggest a central modulation of calcium homeostasis and other central effects for this hormone. The existence of a brain-pituitary axis for certain 1,25(OH)2D3-mediated endocrine-autonomic effects is postulated.

An association between neonatal severe primary hyperparathyroidism and familial hypocalciuric hypercalcemia in three kindreds

Four cases of neonatal severe primary hyperparathyroidism occurred in three families; familial hypocalciuric hypercalcemia was present in each kindred. The diagnosis of familial hypocalciuric hypercalcemia was based on the following features; hypercalcemia in many relatives (eight to 16 per kindred), without other features of the multiple endocrine neoplasia syndromes; recognition of hypercalcemia before the age of 10 in one to three relatives; hypocalciuric hypercalcemia in all relatives tested (five to 14 per kindred); and abnormal serum calcium levels despite parathyroidectomy in all additional relatives (one to five per kindred) undergoing this operation. The association of two uncommon syndromes (neonatal severe primary hyperparathyroidism and familial hypocalciuric hypercalcemia) in these kindreds suggests that the two syndromes share a common genetic cause within each kindred.

Drug-pyridoxal phosphate interactions

In this review it has been pointed out that vitamin B6 and its vitamers can be involved in many interactions with a number of drugs, as well as with the actions of various endocrines and neurotransmitters. Nutritional deficiencies, especially of vitamins and proteins, can affect the manner in which drugs undergo biotransformation, and thereby may also modify the therapeutic efficacy of certain drugs. The differences between nutritional vitamin B6 deficiency and the hereditary disorder producing pyridoxine dependency are discussed. In addition to a pyridoxine deficiency being able to adversely affect drug actions, the improper supplementation with vitamin B6 can in some instances also adversely affect drug efficacy. A decrease by pyridoxine in the efficacy of levodopa used in the treatment of Parkinsonism is an example. The interrelationships and enzymatic interconversions among pyridoxine vitamers, both phosphorylated and non-phosphorylated, are briefly discussed, particularly regarding their pharmacokinetic properties. The ways in which the normal biochemical functions of vitamin B6 may be interfered with by various drugs are reviewed. (1) The chronic administration of isoniazid for the prevention or treatment of tuberculosis can produce peripheral neuropathy which can be prevented by the concurrent administration of pyridoxine. An acute toxic overdose of isoniazid causes generalized convulsions, and the intravenous administration of pyridoxine hydrochloride will prevent or stop these seizures. (2) The acute ingestion of excessive monosodium glutamate will, in some individuals, cause a group of symptoms including among others headache, weakness, stiffness, and heartburn, collectively known as the 'Chinese Restaurant Syndrome.' These symptoms can be prevented by prior supplementation with vitamin B6. The beneficial effect is ascribed to the correction of a deficiency in the activity of glutamic oxaloacetic transaminase, an enzyme that is dependent on pyridoxal phosphate. Some interesting relationships are pointed out between vitamin B6, picolinic acid, and zinc. It is postulated that the intestinal absorption of zinc is facilitated by picolinic acid, a metabolite of tryptophan. The derivation of picolinic acid from tryptophan depends on the action of the enzyme kynureninase, which is dependent on pyridoxal phosphate; therefore, the adequate absorption of zinc is indirectly dependent on an adequate supply of vitamin B6. The formation of pyridoxal phosphate, on the other hand, appears to be indirectly dependent on Zn2++ which activates pyridoxal kinase.(ABSTRACT TRUNCATED AT 400 WORDS)

Congenital heart disease in Nigeria: a ten-year experience at UCH, Ibadan

Of 880 patients who attended the paediatric cardiology unit, University College Hospital, Ibadan, during a ten-year period, 635 (72.2%) had congenital cardiac malformations. Ventricular septal defects were the commonest lesions (35% of the 635 cases), followed by patent ductus arteriosus (22%), Fallot's tetralogy (10%), pulmonary stenosis (9%) and atrial septal defects (7.5%). Coarctation of the aorta was uncommon (2%) and aortic stenosis rare (0.6%). The overall sex incidence was even. Aetiological factors were ascertained in 72 cases (11%). In 60% of these cases intra-uterine rubella was responsible and in 18% perinatal asphyxia. In most patients the cardiac malformation was detected late; consequently complications, such as heart failure, pulmonary hypertension, and polycythaemia were common, even in new patients. Sixty-seven patients (11%) died in hospital, mostly from surgical intervention, heart failure, hypoxaemia, bronchopneumonia and associated extracardiac defects. It is suspected that hypocalcaemia, resulting from vitamin D deficiency may be a cause of the observed low prevalence of obstructive aortic lesions. We suggest that cardiac evaluation be performed at birth in postnatal clinics and in immunization centres, in order to facilitate early detection and treatment of congenital heart disease.

Magnesium (and trace substance) deficiencies in the pathogenesis of cancer

Except for a few experimental models of magnesium (Mg)-deficiency-induced neoplasms, less attention has been paid in the past quarter century in the Western world to this macromineral than to the trace elements; e.g., selenium (Se) and zinc (Zn), and to vitamins, deficiencies of which are each considered probable factors in oncogenesis. Although early epidemiologic studies showed an inverse correlation between the amount of Mg in soil and water and the incidence of (gastric) cancer, and several animal studies supported the premise that Mg has a prophylactic effect against induction of cancer, other studies showed that Mg supplementation increased the growth of established experimental tumors. Thus, enthusiasm for this approach subsided. The early epidemiologic findings have since been confirmed, and there have been studies demonstrating the importance of Mg in maintaining immunocompetence, and others indicating that immunodeficiencies increase susceptibility to the development of cancer. Evidence has now accrued that indicates that Mg deficiency increases susceptibility to chemical oncogens. The abnormal metabolism of tryptophan (yielding a carcinogenic metabolite) that indicates functional or absolute pyridoxine deficiency is an indirect clue to Mg deficiency. Vitamin B6-activated enzymes require Mg as a cofactor. However, the early warnings against the use of Mg as part of an antineoplastic program against established cancer were justified, since rapidly metabolizing cells (such as cancers) are dependent on Mg.There are similarities between experiences with Mg and with Se and Zn. All three are required for normal metabolism; Se also protects against free radicals in the environment. Mg and Zn have increased established tumor growth, and their depletion has been applied to antineoplastic programs, with risks comparable to those of using antimetabolic agents.

Heterotopic calcification in swine

Pigs on nutritional studies developed heterotopic calcifications in the left atrial endocardium, submucosa of the gastric fundus and to a lesser extent in other sites. Light and electron microscopy of mineralized tissue showed early edema and connective tissue change, deposition of calcium, granulomatous reaction and repair. There was no alkaline phosphatase activity at the sites of calcification and the distribution of this enzyme activity was normal in other tissues. Increased acid phosphatase activity was demonstrated only in the lysosomes of macrophages in areas of granulomatous inflammation. Calcium and magnesium were within normal range in serum and femoral bone. The character and distribution of the lesions suggested the possibility of protracted low grade hypervitaminosis D3.

The Williams elfin facies syndrome. A new perspective

Evaluation of 19 patients with the Williams elfin facies syndrome, in order to more completely delineate the total spectrum of the disorder, indicates that "infantile hypercalcemia, peculiar facies, supravalvular aortic stenosis" designation which was heretofore used is inappropriate. Only 32% of the patients have evidence of supravalvular aortic stenosis and not one of them has had documented hypercalcemia, including eight patients who had a serum calcium determination in the first year of life. Rather, the most consistent features are growth deficiency which is predominantly of postnatal onset, mild microcephaly with mental deficiency, and an altered pattern of facial development which includes short palpebral fissures, a stellate pattern in the iris, medial eyebrow flare, a depressed nasal bridge with anteverted nares, and thick lips. The disorder is a sporadic occurrence of unknown etiology.

Calcium metabolism in pregnancy: a review

Calcium metabolism in pregnancy is a complex process involving calcium, phosphorus, vitamin D, parathyroid hormone (PTH), and calcitonin (CT). Calcium absorption is enhanced in pregnancy, and increased storage in the maternal skeleton probably occurs as well. Adequate amounts are provided by the current Recommended Dietary Allowance of 1,200 mg. daily which can be met readily by natural foods, specifically milk. If supplemental calcium is given, a nonphosphate salt is probably advisable, since some evidence suggests that excessive phosphate intake may be related to leg cramps in pregnancy. Vitamin D is necessary for optimal calcium utilization in pregnancy, although the possibility of fetal toxicity with overdosage has been suggested. From a review of available information with respect to maternal-perinatal calcium interrelationships, I propose the following hypothesis: While total maternal serum calcium declines during pregnancy because of the physiologic hypoalbuminemia, the level of ionic calcium remains constant, in part, at least, because of increasing maternal PTH output. The placenta plays a primary role in fetal calcium metabolism by transporting calcium ions from the mother to the fetus against a concentration gradient. Relatively high fetal ionic calcium levels cause suppression of PTH and stimulation of CT in the fetus, facilitating growth of the fetal skeleton. With sudden loss of the placental source of calcium at birth, the newborn infant becomes functionally hypoparathyroid and/or hypercalcitonemic, and the serum calcium level declines until 3 to 4 days of life when PTH rises and CT falls with a resultant slight rise in calcium.

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.

Pathophysiology of aortic baroreceptors in rabbits with vitamin D sclerosis and hypertension

Calciferol (vitamin D 2 ) (50,000-100,000 IU) and calcium lactate (1 g) were added to the normal diet of 22 rabbits for 7-11 days. When mean arterial blood pressure had risen from a control value of 87.2 ± 3.7 mm Hg to an experimental value of 137.8 ± 5.7 mm Hg (11-145 weeks), the aortic arch of 9 of these rabbits was isolated and perfused with Krebs-Henseleit solution. The impulse activity in 75 aortic baroreceptor fibers from the left aortic nerve was studied during nonpulsatile perfusion at different pressures and was compared with the impulse activity in 29 fibers from 17 normal rabbits. The threshold pressures and the pressure at the point of inflection of the curves were lower in these fibers than they were with fibers from normal rabbits. The gradient of the curves relating baroreceptor impulse frequency to aortic pressure was depressed from a normal mean value of 1.19 impulses/sec mm Hg -1 to 0.61 impulses/sec mm Hg -1 ( P < 0.001). A similar depression of the gradient was found in 7 baroreceptor fibers from the right aortic nerve. The change in the sensitivity of the baroreceptors was more closely related to the time interval after the calciferol treatment ( r =-0.95) than it was to the mean arterial blood pressure ( r = -0.76). The pressure-volume curves show that it was also related to the decreased distensibility of the aortic arch region. Histologically, the aortic arch region had extensive medial sclerosis with calcification.