Vitamin C and cancer

Several investigators have reported using vitamin C to treat or prevent cancer, but the data on its effectiveness are inconclusive thus far. In this article, Dr Yamanaka reviews the current thinking on the use of megadoses of vitamin C and the role of nutrition in cancer control. He stresses a diet of fresh fruits and vegetables, foods high in vitamin C and other nutrients, and whole-grain products as the most effective method now available to reduce the incidence of cancer in humans.     

Vitamin D deficiency in patients with malignancy in Brisbane

Purpose

This study aims to investigate the prevalence and factors predictive of vitamin D deficiency in patients with malignancy in Brisbane, Australia (latitude 27° S).

Methods

This is a prospective cross-sectional study measuring serum levels of 25-hydroxyvitamin D (25-OHD) in 100 subjects with non-haematological cancer at least 18 years of age not taking vitamin D supplements attending a day oncology unit and oncology/palliative care inpatient ward in Brisbane, Australia.

Results

Thirty-seven per cent of outpatient and 49 % of inpatient subjects respectively were vitamin D deficient. Functional status was predictive of low vitamin D levels.

Conclusion

There was a high prevalence of vitamin D deficiency in patients with cancer in Brisbane, Australia.     

Vitamin D in older patients with cancer

Vitamin D insufficiency has been found to be as high as 75% among community-dwelling adults aged 65 and older. The purpose of this article is to provide a review of published literature focused on the benefits of vitamin D and calcium supplementation in older patients with cancer. Insufficient vitamin D levels may have considerable effects on cancer-related diagnosis and treatment. Patient education should include information concerning vitamin D and calcium administration to reduce falls and injury from falls and enhance functional status. This article will consider the issue of vitamin D levels related to cancer prevention, diagnosis, treatment, functional status, and falls in older patients with cancer. Dosing and serum measurement information will be discussed.     

Vitamin B12 deficiency

Vitamin B12 (cobalamin) deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders. The role of B12 deficiency in hyperhomocysteinemia and the promotion of atherosclerosis is only now being explored. Diagnosis of vitamin B12 deficiency is typically based on measurement of serum vitamin B12 levels; however, about 50 percent of patients with subclinical disease have normal B12 levels. A more sensitive method of screening for vitamin B12 deficiency is measurement of serum methylmalonic acid and homocysteine levels, which are increased early in vitamin B12 deficiency. Use of the Schilling test for detection of pernicious anemia has been supplanted for the most part by serologic testing for parietal cell and intrinsic factor antibodies. Contrary to prevailing medical practice, studies show that supplementation with oral vitamin B12 is a safe and effective treatment for the B12 deficiency state. Even when intrinsic factor is not present to aid in the absorption of vitamin B12 (pernicious anemia) or in other diseases that affect the usual absorption sites in the terminal ileum, oral therapy remains effective.     

Vitamin K deficiency in the newborn

Newborns have low levels of the vitamin K dependent clotting factors. Early studies were suggestive of vitamin K deficiency. Recently these findings were questioned by studies that failed to detect signs of vitamin K deficiency in the clotting system of newborns using more specific methods, while other studies did find signs of vitamin K deficiency using the same methods. The question was finally solved by direct measurement of vitamin K showing very low levels of the vitamin in the serum of newborns immediately after birth. Whether vitamin K supplementation to the mother reduces the incidence of vitamin K induced changes in the clotting system of newborns remains to be elucidated. In the meantime it seems prudent to administer parenteral vitamin K prophylactically to all newborns immediately after birth.     

Monocyte C1-inhibitor synthesis in patients with C1-inhibitor deficiency

Monocytes of seven out of eight patients with type 1 C1-inhibitor (C1-inh) deficiency (HAE) produced 40% as much C1-inh as monocytes from normal donors (controls). In contrast, monocytes from three patients with type 2 and three patients with acquired C1-inh deficiency produced similar amounts of C1-inh as controls. Recombinant gamma-interferon (gamma-interferon 10 ng/ml) stimulated C1-inh production of C1-inh (eight-10-fold) by control and patients' monocytes. Monocytes from patients with type 1 HAE contained 40% the level of C1-inh messenger ribonucleic acid (mRNA) found in control monocytes. Gamma-interferon increased the abundance of C1-inh mRNA by the same extent in both control and patients' monocytes. C1-inh protein and mRNA were undetectable in the monocytes of one patient, unless stimulated by gamma-interferon. Under these conditions, his monocytes produced comparable amounts of C1-inh (protein and mRNA) as gamma-interferon-stimulated monocytes of the other type 1 HAE patients. The data suggest that in most type 2 HAE patients there is a lesion in the C1-inh gene such that mRNA is transcribed by a single allele.     

Vitamin C and cancer. How convincing a connection?

More research is needed to draw definitive conclusions on the relationship between vitamin C intake and cancer, but the following general statements can be made. The effectiveness of megadoses (greater than 1 gm/day) of vitamin C for the cure or prevention of cancer is still unproven; in fact, the safety of megadoses is still in question. Therefore, they are not recommended for the general public at present and, if used at all, should be used under medical supervision. Epidemiologic evidence suggests that vitamin C-rich foods may be beneficial in preventing cancer, and their consumption should be encouraged as a measure to reduce the incidence of cancer. Well-controlled studies should be undertaken to elucidate the relationship between vitamin C and cancer, using both vitamin-containing foods and vitamin C supplements at different intake levels.