Niacin and Cancer

Cancer and Niacin Study,

Studies of cultured cells (in vitro) provide evidence that NAD content influences the cellular response to DNA damage, an important risk factor in cancer development. Cellular NAD is consumed in the synthesis of ADP-ribose polymers, which play a role in DNA repair, and cyclic ADP-ribose may also mediate cell-signaling pathways important in cancer prevention (11). Additionally, cellular depletion of NAD has been found to decrease levels of the tumor suppressor protein, p53, in human breast, skin, and lung cells (10). Neither the cellular NAD content nor the dietary intake of NAD precursors (niacin and tryptophan) necessary for optimizing protective responses following DNA damage has been determined, but both are likely to be higher than that required for the prevention of pellagra. Niacin deficiency was found to decrease bone marrow NAD and poly-ADP-ribose levels and increase the risk of chemically induced leukemia (12). Moreover, one study reported that niacin supplementation decreased the risk of ultraviolet light-induced skin cancers in mice (13). However, little is known regarding cellular NAD levels and the prevention of DNA damage or cancer in humans. One study in two healthy individuals involved elevating NAD levels in blood lymphocytes by supplementation with 100 mg/day nicotinic acid/day for eight weeks. Compared to non-supplemented individuals, the supplemented individuals had reduced DNA strand breaks in lymphocytes exposed to free radicals in a test tube assay (14). More recently, nicotinic acid supplementation of up to 100 mg/day in 21 healthy smokers failed to provide any evidence of a decrease in cigarette smoke-induced genetic damage in blood lymphocytes compared to placebo (15).

Generally, relationships between dietary factors and cancer are established first in epidemiological studies and followed up by basic cancer research at the cellular level. In the case of niacin, research on biochemical and cellular aspects of DNA repair has stimulated an interest in the relationship between niacin intake and cancer risk in human populations (16). Recently, a large case-control study found increased consumption of niacin, along with antioxidant nutrients, to be associated with decreased incidence of oral (mouth), pharyngeal (throat), and esophageal cancers in northern Italy and Switzerland (17, 18). An increase in niacin intake of 6.2 mg was associated with about a 40% decrease in cases of cancers of the mouth and throat, while a 5.2 mg increase in niacin intake was associated with a similar decrease in cases of esophageal cancer.


Full Document at http://lpi.oregonstate.edu/infocenter/vitamins/niacin/

Vitamin D and Cancer

Vitamin D and breast cancer

SAN DIEGO, CA.

A report has just appeared in the Journal of Steroid Biochemistry & Molecular Biology by Garland et al that addresses the issue of vitamin D and breast cancer risk with a pooled analysis of studies that determined the vitamin D status from serum 25-hydroxyvitamin D (25(OH)D) levels. The list of authors includes both well-known vitamin D experts and nutritional epidemiologists. The authors were only able to find two studies that met their requirements for inclusion in their pooled analysis, but together they involved 1760 individuals. Both studies covered a wide range of 25(OH)D levels and exhibited a high level of inverse correlation between breast cancer risk and the serum level of this vitamin D marker. When pooled analysis was carried out, the odds ratios for the lowest to highest quintile of 25(OH)D levels were 1.00, 0.90, 0.70, 0.70 and 0.50, i.e. the highest vitamin D status provided a 50% reduction in risk. The authors present a graph of risk (odds ratio) against serum 25(OH)D levels with an amazing correlation coefficient of 0.94 (a statistical measure of the goodness of fit to the model, in this case a straight line, and 1.00 represents a perfect fit), a correlation coefficient that would please those trained in the physical sciences and in fact a correlation very rarely seen in plots presented in the medical literature.
The authors discuss the level of intake that would accomplish the 50% level of risk reduction. If a person were to start at a serum level of 24 nmol/L (10 ng/mL) it would require supplementation of 4000 IU/day to achieve the required level of 120 nmol/L. This exceeds the current upper limit of 2000 IU/day. However, as they point out, a proposal has been made to raise this limit to 4000 IU/day. Levels of 24 nmol/L are not uncommon among US women in the winter months. An alternative they explore is to take 2000 IU/day orally and make up the balance by judicious sun exposure. They estimate that 12 minutes of sun exposure for 50% of the skin would produce the missing 2000 IU. However, this would not happen in the northern latitudes in the winter months. The authors hammer home their point regarding the importance of vitamin D by calculating that, based on their data, an intake of 4000 IU of vitamin D per day would, in the U.S., prevent over 100,000 cases of breast cancer per year. Intake of 2000 IU/day was estimated to prevent 66,000 cases. In this paper, vitamin D refers to vitamin D3. Garland, C. F. et al. Vitamin D and the Prevention of Breast Cancer; Pooled Analysis. Journal of Steroid Biochemistry & Molecular Biology, 2007, Vol. 103, pp. 708-711.

Olive Oil and Breast Cancer

Olive oil helps combat breast cancer.

There is ample evidence that the diet consumed in Mediterranean countries helps protect women against breast cancer. Now Professor Javier Menendez and his team at Northwestern University in Chicago suggest that olive oil may be the main protector. Dr. Menendez found that oleic acid, the major fatty acid in olive oil, is highly effective in killing the Her2/neu protein, a major factor in the growth of breast cancer tumours. The oil is, as a matter of fact, just as effective as the anticancer drug Herceptin and, when combined with this drug, results in a reduction of 70% in Her2/neu levels (in test tube experiments). Dr. Menendez suggests that olive oil manufacturers should begin to list the total oleic acid content on their products so that consumers can select the best brand for cancer prevention.New Scientist, January 15, 2005, p. 7

Beta-Carotene and Breast Cancer

Beta-carotene and breast cancer

NEW YORK, NY.

Carotenoids, like beta-carotene, are important constituents of fruits and vegetables. Numerous studies have investigated the association between the dietary intake of carotenoids and the risk of breast cancer. Some have found a beneficial effect, others have not. Researchers at the New York University School of Medicine now weigh in with the results of a new study that shows a clear benefit of carotenoids. Their study involved 270 women diagnosed with breast cancer and 270 matched controls (125 pre- and 145 postmenopausal in each group). All the participants had blood samples taken at the beginning of the study in 1985 (at least 6 months and more likely an average of four years prior to the cancer diagnosis). These samples were frozen at minus 80 degrees Celsius until analysis in 1995. The researchers found that women with the lowest levels of carotenoids in their blood serum had twice the incidence of breast cancer than did women with the highest levels (highest quartile). The specific odds ratios were 2.21 for beta-carotene, 2.08 for lutein, 1.68 for beta-cryptoxanthin, and 2.0 for alpha-carotene. The researchers conclude that, “These observations offer evidence that a low intake of carotenoids, through poor diet and/or lack of vitamin supplementation, may be associated with an increased risk of breast cancer.”Toniolo, Paolo, et al. Serum carotenoids and breast cancer. American Journal of Epidemiology, Vol. 153, June 15, 2001, pp. 1142-51