Folacin and iron status and hematological findings in predominately black elderly persons from urban low-income households

Gene-gene, gene-environment & multiple interactions in colorectal cancer

This review comprehensively evaluates the influence of gene-gene, gene-environment and multiple interactions on the risk of colorectal cancer (CRC). Methods of studying these interactions and their limitations have been discussed herein. There is a need to develop biomarkers of exposure and of risk that are sensitive, specific, present in the pathway of the disease, and that have been clinically tested for routine use. The influence of inherited variation (polymorphism) in several genes has been discussed in this review; however, due to study limitations and confounders, it is difficult to conclude which ones are associated with the highest risk (either individually or in combination with environmental factors) to CRC. The majority of the sporadic cancer is believed to be due to modification of mutation risk by other genetic and/or environmental factors. Micronutrient deficiency may explain the association between low consumption of fruit/vegetables and CRC in human studies. Mitochondrial modulation by dietary factors influences the balance between cell renewal and death critical in colon mucosal homeostasis. Both genetic and epigenetic interactions are intricately dependent on each other, and collectively influence the process of colorectal tumorigenesis. The genetic and environmental interactions present a good prospect and a challenge for prevention strategies for CRC because they support the view that this highly prevalent cancer is preventable.

Primary prevention: phytoprevention and chemoprevention of colorectal cancer

Considering the various stages of carcinogenesis and the numerous tumor types and available chemoprevention agents, knowledge of the etiology and the type of cancer to be treated, or possibly prevented, and understanding of the mechanisms by which agents exert their chemoprevention benefits may provide for improved strategy in designing therapeutic regimens. Because cancer usually develops over a 10- to 20-year period, it may be necessary for some agents to be provided before or early in the initiation steps of carcinogenesis to have beneficial effects. On the other hand, some agents may be more suitable for CRC prevention if provided at a later stage of carcinogenesis. Gene array, genomics, and proteomics are useful tools in advancing our understanding of the molecular events involved in carcinogenesis and in identifying markers of risk and surrogate end-points for colorectal cancer progression. These techniques may also serve for screening, identifying, and providing treatment targets for high-risk patients populations. Treatment could be developed depending on a patient's individual needs and genomic tumor profile. Clinical markers and surrogate end-points should be considered, together with molecular measurements, to more accurately assess risk. NSAIDs and COXIBs are clinically recognized as chemoprevention agents, and clinical trials evaluating their efficacy are ongoing. Treatment protocols, including dose and timing, remain to be determined, however. DFMO may best be used in combination with other chemoprevention agents. Dietary fiber and calcium supplements, as part of an overall low-fat diet, may decrease CRC risk. Long-term compliance with this regimen may be necessary to effect a beneficial outcome. Folate holds promise but needs further investigation, especially because its beneficial effects may depend on cancer type. Phytochemicals have been identified as strong candidates for use as agents to prevent colorectal cancer in cell culture and in rodent models of carcinogenesis. Their potential as chemoprevention agents must be demonstrated in clinical trials. In vitro and animal studies indicated that combination therapy may be a promising strategy over the monotherapy approach; clinical trials addressing the safety and efficacy of some combinations (DFMO/sulindac, fiber/calcium) are underway. The gastrointestinal tract and other organs are constantly exposed to a mixture of potentially toxic compounds and molecules considered favorable to health. Homeostasis between stress-mediated by toxic compounds and defensive mechanisms, is key for the maintenance of health and the prevention of disease. Whereas aggressive pharmacologic treatment may be necessary for patients at high risk for cancer, dietary supplements may be useful for populations at normal risk. The message for cancer prevention in the general population may well remain: keep a balanced healthy diet, eating a variety from all food groups, as part of a healthy lifestyle that includes moderate exercise.

DNA damage from micronutrient deficiencies is likely to be a major cause of cancer

A deficiency of any of the micronutrients: folic acid, Vitamin B12, Vitamin B6, niacin, Vitamin C, Vitamin E, iron, or zinc, mimics radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions, or both. For example, the percentage of the US population that has a low intake (<50% of the RDA) for each of these eight micronutrients ranges from 2 to >20%. A level of folate deficiency causing chromosome breaks was present in approximately 10% of the US population, and in a much higher percentage of the poor. Folate deficiency causes extensive incorporation of uracil into human DNA (4 million/cell), leading to chromosomal breaks. This mechanism is the likely cause of the increased colon cancer risk associated with low folate intake. Some evidence, and mechanistic considerations, suggest that Vitamin B12 (14% US elderly) and B6 (10% of US) deficiencies also cause high uracil and chromosome breaks. Micronutrient deficiency may explain, in good part, why the quarter of the population that eats the fewest fruits and vegetables (five portions a day is advised) has about double the cancer rate for most types of cancer when compared to the quarter with the highest intake. For example, 80% of American children and adolescents and 68% of adults do not eat five portions a day. Common micronutrient deficiencies are likely to damage DNA by the same mechanism as radiation and many chemicals, appear to be orders of magnitude more important, and should be compared for perspective. Remedying micronutrient deficiencies should lead to a major improvement in health and an increase in longevity at low cost.

Micronutrient deficiencies. A major cause of DNA damage

Deficiencies of the vitamins B12, B6, C, E, folate, or niacin, or of iron or zinc mimic radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions, or both. The percentage of the population of the United States that has a low intake (< 50% of the RDA) for each of these eight micronutrients ranges from 2% to 20+ percent. A level of folate deficiency causing chromosome breaks occurred in approximately 10% of the population of the United States, and in a much higher percentage of the poor. Folate deficiency causes extensive incorporation of uracil into human DNA (4 million/cell), leading to chromosomal breaks. This mechanism is the likely cause of the increased colon cancer risk associated with low folate intake. Some evidence, and mechanistic considerations, suggest that vitamin B12 and B6 deficiencies also cause high uracil and chromosome breaks. Micronutrient deficiency may explain, in good part, why the quarter of the population that eats the fewest fruits and vegetables (five portions a day is advised) has about double the cancer rate for most types of cancer when compared to the quarter with the highest intake. Eighty percent of American children and adolescents and 68% of adults do not eat five portions a day. Common micronutrient deficiencies are likely to damage DNA by the same mechanism as radiation and many chemicals, appear to be orders of magnitude more important, and should be compared for perspective. Remedying micronutrient deficiencies is likely to lead to a major improvement in health and an increase in longevity at low cost.

Paracelsus to parascience: the environmental cancer distraction

Entering a new millennium seems a good time to challenge some old ideas, which in our view are implausible, have little supportive evidence, and might best be left behind. In this essay, we summarize a decade of work, raising four issues that involve toxicology, nutrition, public health, and government regulatory policy. (a) Paracelsus or parascience: the dose (trace) makes the poison. Half of all chemicals, whether natural or synthetic, are positive in high-dose rodent cancer tests. These results are unlikely to be relevant at the low doses of human exposure. (b) Even Rachel Carson was made of chemicals: natural vs. synthetic chemicals. Human exposure to naturally occurring rodent carcinogens is ubiquitous, and dwarfs the general public's exposure to synthetic rodent carcinogens. (c) Errors of omission: micronutrient inadequacy is genotoxic. The major causes of cancer (other than smoking) do not involve exogenous carcinogenic chemicals: dietary imbalances, hormonal factors, infection and inflammation, and genetic factors. Insufficiency of many micronutrients, which appears to mimic radiation, is a preventable source of DNA damage. (d) Damage by distraction: regulating low hypothetical risks. Putting huge amounts of money into minuscule hypothetical risks damages public health by diverting resources and distracting the public from major risks.

Micronutrients prevent cancer and delay aging

Approximately 40 micronutrients are required in the human diet. Deficiency of vitamins B12, folic acid, B6, niacin, C, or E, or iron, or zinc, appears to mimic radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions, or both. The percentage of the US population that has a low intake (< 50% of the RDA) for each of these eight micronutrients ranges from 2% to > or = 20%; half of the population may be deficient in at least one of these micronutrients. Folate deficiency occurs in approximately 10% of the US population, and in a much higher percentage of the poor. Folate deficiency causes extensive incorporation of uracil into human DNA (4 million/cell), leading to chromosomal breaks. This mechanism is the likely cause of the increased cancer risk, and perhaps the cognitive defects associated with low folate intake. Some evidence, and mechanistic considerations, suggest that vitamin B12 and B6 deficiencies also cause high uracil and chromosome breaks. Micronutrient deficiency may explain, in good part, why the quarter of the population that eats the fewest fruits and vegetables (five portions a day is advised) has approximately double the cancer rate for most types of cancer when compared to the quarter with the highest intake. Eighty percent of American children and adolescents and 68% of adults do not eat five portions a day. Common micronutrient deficiencies are likely to damage DNA by the same mechanism as radiation and many chemicals, appear to be orders of magnitude more important, and should be compared for perspective. Remedying micronutrient deficiencies is likely to lead to a major improvement in health and an increase in longevity at low cost. Aging appears to be due, in good part, to the oxidants produced by mitochondria as by-products of normal metabolism. In old rats mitochondrial membrane potential, cardiolipin levels, respiratory control ratio, and overall cellular O2 consumption are lower than in young rats, and the level of oxidants (per unit O2) is higher. The level of mutagenic aldehydes from lipid peroxidation is also increased. Ambulatory activity declines markedly in old rats. Feeding old rats the normal mitochondrial metabolites acetyl carnitine and lipoic acid for a few weeks, restores mitochondrial function, lowers oxidants to the level of a young rat, and increases ambulatory activity. Thus, these two metabolites can be considered necessary for health in old age and are therefore conditional micronutrients. This restoration suggests a plausible mechanism: with age-increased oxidative damage to proteins and lipid membranes causes a deformation of structure of key enzymes, with a consequent lessening of affinity (Km) for the enzyme substrate; an increased level of the substrate restores the velocity of the reaction, and thus restores function.

The prevention of cancer

1. The major causes of cancer are as follows: (a) Smoking: about a third of U.S. cancer (90% of lung cancer). (b) Dietary imbalances, e.g., lack of dietary fruits and vegetables: The quarter of the population eating the least fruits and vegetables has double the cancer rate for most types of cancer compared to the quarter eating the most; micronutrients may account for much of the protective effect of fruits and vegetables. Excess calories may also contribute to cancer. (c) Chronic infections: mostly in developing countries. (d) Hormonal factors influenced by life-style. 2. There is no epidemic of cancer, except for lung cancer due to smoking. Cancer mortality rates have declined 16% since 1950 (excluding lung cancer and adjusted for the increased life span of the population). 3. Regulatory policy that is focused on traces of synthetic chemicals is based on misconceptions about animal cancer tests. Recent research contradicts these ideas: (a) Rodent carcinogens are not rare. Half of all chemicals tested in standard high-dose animal cancer tests, whether occurring naturally or produced synthetically, are "carcinogens." (b) There are high-dose effects in these rodent cancer tests that are not relevant to low-dose human exposures and which can explain the high proportion of carcinogens. (c) Though 99.9% of the chemicals humans ingest are natural, the focus of regulatory policy is on synthetic chemicals. Over 1000 chemicals have been described in coffee: 27 have been tested and 19 are rodent carcinogens. Plants that we eat contain thousands of natural pesticides which protect plants from insects and other predators: 64 have been tested and 35 are rodent carcinogens. 4. There is no convincing evidence that synthetic chemical pollutants are important for human cancer. Regulations that try to eliminate minuscule levels of synthetic chemicals are enormously expensive: EPA estimates that total expenditures on environmental regulations cost $140 billion/year. It has been estimated by others that the United States spends 100 times more to prevent one hypothetical, highly uncertain death from a synthetic chemical than it spends to save a life by medical intervention. Attempting to reduce tiny hypothetical risks also has costs; for example, if reducing synthetic pesticides makes fruits and vegetables more expensive, thereby decreasing consumption, then cancer will be increased. 5. Improved health will come from knowledge due to biomedical research and from life-style changes by individuals. Little money is spent on biomedical research or on educating the public about lifestyle hazards, compared to the cost of regulations.

Folate deficiency causes uracil misincorporation into human DNA and chromosome breakage: implications for cancer and neuronal damage

Folate deficiency causes massive incorporation of uracil into human DNA (4 million per cell) and chromosome breaks. The likely mechanism is the deficient methylation of dUMP to dTMP and subsequent incorporation of uracil into DNA by DNA polymerase. During repair of uracil in DNA, transient nicks are formed; two opposing nicks could lead to chromosome breaks. Both high DNA uracil levels and elevated micronucleus frequency (a measure of chromosome breaks) are reversed by folate administration. A significant proportion of the U.S. population has low folate levels, in the range associated with elevated uracil misincorporation and chromosome breaks. Such breaks could contribute to the increased risk of cancer and cognitive defects associated with folate deficiency in humans.

Cobalamin and folate deficiency in the elderly

Elderly persons are more likely to have low values for serum and erythrocyte folate, and for serum cobalamin. Many of those with low vitamin levels have biochemical abnormalities consistent with true deficiency, including increased formiminoglutamic acid excretion, abnormal marrow deoxyuridine suppression, and raised serum levels of methylmalonic acid and homocysteine. Therapy with the appropriate vitamin reverses the biochemical defect. Despite this, the clinical consequences for most elderly persons are remarkably few. True megaloblastic anaemia is rare, and the small number of therapeutic trials to date have not improved the levels of haemoglobin in the treated subjects, although the mean corpuscular volume has decreased significantly. There has been recent concern that these low blood vitamin levels might be important causes of nervous system damage, but studies specifically of the elderly have not demonstrated overall improvements in neurological function following therapy. Vascular damage from high blood homocysteine levels secondary to cobalamin or folate deficiency remains a potential hazard. Dietary insufficiency, malabsorption of protein-bound vitamin B12 secondary to atrophic gastritis, and defective absorption of folyl polyglutamates seem the likeliest possible causes. Pernicious anaemia, although a common cause of severe megaloblastic anaemia in the elderly, is an infrequent cause for the low cobalamin levels in population studies. Although the benefits are uncertain, the balance of the evidence suggests that one should treat elderly persons with low values of cobalamin or folate. Crystalline vitamin B12 and folic acid are absorbed normally and are therefore suitable for replacement therapy, provided that pernicious anaemia is excluded.

The causes and prevention of cancer

Epidemiological evidence indicates that avoidance of smoking, increased consumption of fruits and vegetables, and control of infections will have a major effect on reducing rates of cancer. Other factors include avoidance of intense sun exposure, increases in physical activity, and reduction of alcohol consumption and possibly red meat. A substantial reduction in breast cancer is likely to require modification of sex hormone levels, and development of practical methods for doing so is a high research priority. Resolution of the potential protective roles of specific antioxidants and other constituents of fruits and vegetables deserves major attention. Mechanistic studies of carcinogenesis indicate an important role of endogenous oxidative damage to DNA that is balanced by elaborate defense and repair processes. Also key is the rate of cell division, which is influenced by hormones, growth, cytotoxicity, and inflammation, as this determines the probability of converting DNA lesions to mutations. These mechanisms may underlie many epidemiologic observations.

Anemia and nutritional deficiency in the acutely ill hospitalized patients

Hospitalized patients may present with nutritional deficiencies or develop them during the hospitalization. The physician should remain alert to the presence of these readily correctable conditions.

Prevalence of folate deficiency in emergency department patients with alcohol-related illness or injury

To assess the prevalence of folate deficiency in emergency department patients with alcohol-related illness or injury, a prospective, nonconsecutive case series with nonrandomized controls was used. All patients presenting to a 60,000-visit public hospital emergency department with alcohol-related illness or injury were eligible; patients were excluded if they had received folate in our health care facility within the previous 4 months. An alcohol and brief dietary history was obtained, and a complete blood cell count and red blood cell folate level was performed on each patient. Analysis was undertaken by chi 2 to evaluate the prevalence of folate deficiency in the alcohol-related versus the control population. One hundred three patients were entered into the study. Three patients were subsequently excluded from analysis. Of 52 study patients, three (5.8%) were found to be folate deficient. Of 48 controls, two (4.2%) were found to be folate deficient. This difference is not statistically significant (P greater than .05, chi 2; mean difference 1.6%, 95% confidence interval -6.9% to 10.1%). The prevalence of folate deficiency in patients presenting to this emergency department with alcohol-related illness or injury is low, and does not differ from the general emergency department population. Empiric folate therapy in these patients is not indicated.

Effect of residual splenic function and folate levels on the frequency of micronucleated red blood cells in splenectomized humans

Frequencies of micronucleated erythrocytes in the peripheral blood of splenectomized individuals can be used as an index of genetic damage to erythrocyte precursor cells in the bone marrow. This is in contrast to non-splenectomized humans, whose micronucleated erythrocytes are removed by the spleen. Many subjects whose spleen has been removed surgically have residual spleen tissue and consequent residual spleen function (RSF), which can be measured by the percentage of 'pitted' peripheral red blood cells. In this study evidence of RSF was associated with decreased frequencies of micronucleated erythrocytes. Analysis of data limited to subjects with minimal spleen function suggested an inverse association between the incidence of micronucleated erythrocytes and serum folate levels that was not apparent in the absence of stringent control for RSF.

Cytogenetic damage induced by folate deficiency in mice is enhanced by caffeine

Folate deficiency in Swiss mice increased the incidence of micronuclei in peripheral blood erythrocytes, indicating increased chromosomal damage in nucleated erythrocyte precursors. Caffeine enhanced the incidence of micronuclei in blood and bone marrow by up to 5-fold in folate-deficient mice at doses that did not significantly alter the micronucleus frequency in the presence of adequate dietary folate. The lower dose of caffeine used in this study (75 mg/kg) approaches doses received by humans who consume large amounts of caffeinated beverages. Since folate deficiency and caffeine consumption are highly prevalent in the human population, the potential for a similar interaction in man should be evaluated.

Folic acid malabsorption in atrophic gastritis. Possible compensation by bacterial folate synthesis

Folic acid absorption was studied in 12 elderly subjects with atrophic gastritis and 10 elderly normal controls using tritium-labeled pteroylmonoglutamic acid. Two folic acid absorption tests were carried out on each subject with 120 ml of either water or 0.1 N HCl. Folic acid absorption was significantly lower in subjects with atrophic gastritis than in normal controls (31% vs. 51%, respectively; p less than 0.01). In subjects with atrophic gastritis, folic acid absorption rose significantly to 54% (p less than 0.001) when administered with acid, but did not change in normal controls (50%). Serum folate levels were normal in all subjects. Proximal small intestinal pH was higher in atrophic gastritis subjects than in normal controls (7.1 vs. 6.7, respectively; p less than 0.05), as were bacterial counts of small intestinal fluid (p less than 0.01). Bacteria cultured from the aspirates of subjects with atrophic gastritis were able to synthesize folate in vitro when incubated in a folate-free medium. Atrophic gastritis results in folic acid malabsorption but not in folate deficiency, possibly due to increased bacterial synthesis of folate in the small intestine.

Folate and vitamin B12 levels in an urban elderly population with chronic diseases. Assessment of two laboratory folate assays: microbiologic and radioassay

Folate levels of serum and red blood cells (RBC) and vitamin B12 serum levels were investigated in 326 urban chronically ill elderly ambulatory patients and 41 healthy young control subjects. Two laboratory methods were used for investigating the folate levels, the microbiologic assay (MBA) with Lactobacillus casei and radioassay (RA). Serum and RBC samples of 326 patients were tested by the folate MBA and 270 of the same samples by the RIA methods. In the MBA 6.8% of the patients and 12.2% of controls had low levels of folate RBC (less than 200 ng/mL) and 1.8% of patients and 4.8% of controls had low serum folate levels (less than 5 ng/mL). All of the patients with the low folate levels had normal hematologic findings and no clinical symptoms of folate deficiency. In the RIA method, all of the patients and almost all of the control subjects (except one) had normal folate levels. Ten of the patients (3%) had low levels of serum vitamin B12 (less than 200 pg/mL). They were hematologically normal. They had normal Schilling tests and normal vitamin B12 dietary intake. Their RBC folate levels were normal and even somewhat higher. Forty percent of these patients had macular degeneration of the eyes. The data indicate the superiority of the RA method over the MBA and bring into question the accuracy of previous studies. The data furnish further evidence that a low vitamin B12 level in the elderly is not necessarily a true vitamin B12 deficiency and raise the possibility of an association between low B12 serum levels and macular degeneration of the eyes.

Folate and vitamin B12 (cobalamin) blood levels in elderly persons in geriatric homes

Significantly lower mean plasma and whole blood folate levels were noted in elderly persons in geriatric homes as compared to mean values of a reference sample group. The vitamin B12 levels of the elderly persons did not differ significantly from the reference values. More elderly, however, had low B12 values when assayed with a specific binder than when assayed with a non-specific binder. This probably means that B12 analogues are more frequently present in elderly persons in geriatric homes than in subjects in the reference sample group. One half of the disabled elderly persons had low B12 and/or low folate levels as compared to only one fifth of the not disabled elderly persons. Hypersegmentation of neutrophils in peripheral blood was observed in elderly persons who had low levels of B12 as well as of both plasma and whole blood folate. Those with normal values of at least one of these variables did not have hypersegmentation more frequently than those with normal B12 and folate values, implying that isolated low values of either B12 or folate is not synonymous with functional deficiency.

Effect of folate deficiency on microsomal drug metabolism and heme content in the intestinal mucosa of guinea pigs

The relationship between folate deficiency, heme content, and microsomal drug metabolism in the intestinal mucosa of the guinea pig was examined. Weanling male guinea pigs were pair-fed a folate-deficient diet, and intestinal mucosal folate levels were measured. A significant decrease (75%) in these levels was observed at 3 weeks after diet initiation. A significant decrease (78%) in intestinal mucosal drug metabolism (7-ethoxycoumarin O-deethylase activity) and a significant decrease (46%) in intestinal mucosal heme content were also observed at this time. These findings indicate that folic acid deficiency in the guinea pig results in a marked reduction in heme content and microsomal drug metabolism of the intestinal mucosa.

Vitamin B12 status of elderly persons from urban low-income households

Vitamin B12 status was evaluated in 111 noninstitutional elderly persons (age range, 60-87 years) living in an urban poverty area. The sample was predominantly black (90 subjects); the rest were Spanish Americans. Serum vitamin B12 levels were all normal (greater than 200 pg/ml) and ranged from 226 to 1200 pg/ml (mean +/- SD = 700 +/- 191 pg/ml). The findings indicate that vitamin B12 deficiency was not a problem in this elderly population.