DIET/Fiber 

Dietary Fiber Not a Magic Bullet

For years, a high intake of dietary fiber has been accepted as an appropriate way to reduce the risk of colorectal cancer. This major nutrition study published in The New England Journal of Medicine calls this common practice into question.

The study employs data gathered in the Nurses' Health Study of 121,700 registered nurses age 30 to 5

Initiated in 1976, this massive study involved completion of mailed questionnaires on known or suspected risk factors for cancer and coronary heart disease.

The current study involved 88,757 women 34 to 59 who had no history of cancer, inflammatory bowel disease, or familial polyposis. Cases of colorectal cancer and adenomas were documented over the 16-year follow-up period. This study produced results that have stirred the health care and nutrition communities and the food industry. The researchers found "no evidence support the hypothesis that total dietary fiber intake is protective against colorectal cancer or adenoma."

The authors make a strong case that the long-held belief in the utility of high-fiber diets to prevent colorectal cancer was based mostly on theories and to a very small degree on substantive scientific evidence.

Fiber Intake Lowers Risk of Mouth and Throat Cancers

Higher fiber intake may be protective against oral, pharyngeal and esophageal cancer. In a recent study, data from a prior study was investigated as to the correlation between consumption of various types of fiber and oral, pharyngeal and esophageal cancer.

Cases included 271 patients with oral cancer, 327 with pharyngeal cancer and 304 with esophageal cancer.Controls included 1950 subjects with acute, nonneoplastic diseases. The subjects' dietary habits were collected using a food frequency questionnaire. The researchers calculated the relative risk of sustaining one of the forms of cancer after adjusting the data for age, sex, and other confounding factors, including alcohol and tobacco consumption and energy intake. 

Results: People who consumed the most fruit, vegetables and whole grain cereals had a lower risk of these cancers compared with people who consumed the least amount. Soluble fiber found in foods such as oatmeal and fruit, and insoluble fiber found in seeds and the skin of the fruit, were both protective. The results were equal for both sexes.

Conclusion: The results confirmed the findings of other studies of upper digestive tract neoplasms. Also, the authors note that high fiber intake may be a marker for a healthier lifestyle that includes lower intake of meat and foods rich in saturated fat and cholesterol, and higher intake of low-fat foods such as fruits and vegetables.

Regular High-Fiber Breakfast Associated With Maintaining Healthy Weight in Girls

Previous research has shown that children who consume breakfast regularly are much more likely to meet recommended intakes of vitamins and minerals than children who do not. This may be attributed to the consumption of breakfast cereals, many of which are fortified with essential nutrients, and provide dietary fiber.

Research has also shown that children who eat cereals consume significantly less fat and cholesterol than children who eat other foods for breakfast. However, less is known about the relationship between consumption of cereal and body mass index in children.

In this paper, researchers analyzed data from a 10-year longitudinal cohort study of more than 2,300 adolescent girls, all of whom were 9 or 10 years old at the start of the study. Dietary habits were tracked annually, using a three-day food questionnaire that documented the frequency of breakfast consumption and whether cereal was consumed as part of breakfast, along with intakes of dietary fiber, fat, calcium, iron, folic acid, vitamin C, and zinc.

Results: "Compared with girls who ate cereal on 0 days, girls who ate cereal on 1, 2, or 3 days were 0.93, 0.90, and 0.87 times as likely to be at risk of overweight; that is, eating cereal on 1 or more days resulted in a reduction in risk of overweight," the scientists wrote. In addition, "a similar trend was seen for breakfast consumption, with those consuming breakfast on 3 days having lower BMIs than girls who skipped breakfast on all or most days."

In the study's conclusion, the authors stated that their analysis "clearly demonstrated that cereal consumption was predictive of lower BMI" in adolescent females. They added that cereal consumption "had positive effects on nutrient intake in girls, resulting in diets significantly lower in fat and cholesterol." 

Fiber May Benefit Diabetes Patients

Recent American Diabetes Association (ADA) dietary guidelines for patients with diabetes mellitus recommend that dietary composition be based on individualized nutritional assessments and target individual desired outcomes.

Among these recommendations is an increase in dietary fiber intake from 20 to 35 grams per day as a means of regulating cholesterol levels.

The effects of dietary fiber on glycemic control were considered inconsequential, and the ADA expert panel determined that it would be difficult for one to consume adequate dietary fiber unless food sources were supplemented or fortified with fiber. The present study determined the effects of increasing dietary fiber in type 2 diabetes patients solely through the consumption of foods not fortified with fiber, to a fiber level beyond that recommended by the ADA.

Thirteen patients were assigned to follow two diets for six weeks each: a diet containing moderate amounts of fiber (24 grams total - 8 grams soluble, 16 grams insoluble), and a diet containing high amounts of fiber (50 grams total - 25 grams soluble, 25 grams insoluble). Both diets contained identical macronutrients and energy content, and were compared with regard to their influence on glycemic control and plasma lipid concentrations.

High daily fiber intake improved glycemic control, evidenced by decreases in average daily preprandial and 24-hour plasma glucose concentrations. In addition, the high-fiber diet lowered urinary glucose excretion and 24-hour plasma insulin concentrations. The authors note that fiber intake was not achieved by consuming fiber-fortified foods and that patients reported few side effects from the high-fiber diet. They suggest that dietary guidelines for patients with diabetes include an overall increase in dietary fiber without relying on the use of fiber 

 Diet/Sodium

Reduced Salt & Healthy Eating = Reduced Blood Pressure

Evidence suggests that a diet that emphasizes healthy eating habits significantly lowers blood pressure in people who have hypertension and even normal blood pressure. This diet is often known as the DASH (Dietary Approaches to Stop Hypertension) diet and is outlined as follows:

* Emphasis on fruits, vegetables, and low-fat dairy foods.
* Includes whole grains, poultry, fish, and nuts.
* Contains small amounts of red meats, sweets, and sugar containing beverages.

This study aimed further to define the effect of salt on blood pressure and to investigate the effect of a combined low salt / DASH diet.

Four hundred and twelve subjects were randomly assigned to eat a controlled diet, which was typical of a normal US diet, or the DASH diet. Within each dietary group, subjects ate foods with a high, intermediate and low level of salt for 30 days.

Reducing sodium intake from the high to the intermediate level reduced the mean systolic blood pressure among those on the control diet by 2.1 mm Hg and 1.3 mm Hg for those on the DASH diet. When salt was reduced to the lowest level, there was an additional reduction in systolic pressure among those receiving the control diet and for those on the DASH diet. The greatest reduction in systolic blood pressure occurred in subjects consuming the low-salt DASH diet, representing a 7.5 mm Hg decrease in non-hypertensive patients and 11.5 mm Hg decrease in those with hypertension.

Conclusion: the reduction of sodium intake to levels below the current recommendation of 100 mmol/d and the DASH diet both lower blood pressure substantially, with greater effects in combination. Long-term health benefits will depend on the ability of people to make long-lasting dietary changes and the increased availability of lower-sodium foods.

Note: The duration of this study was very brief - only 30 days. Yet there were still significant decreases in systolic blood pressure. Even greater potential improvement in blood pressure may be possible if patients adhere to a diet that is low in sodium and combines principles of the DASH diet.

High-Sodium Diet and Congestive Heart Failure

In contrast to declines in mortality related to coronary heart disease and stroke, more Americans are dying from congestive heart failure (CHF); roughly 4.7 million in the U.S. experience CHF annually.

High sodium intake may increase the risk for left ventricular hypertrophy, based on previous studies.

Utilizing the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, the authors of this study compared CHF cases in 5,233 normal-weight and 5,129 overweight (BMI over 25) subjects. Up to 21 years after an initial 24-hour diet recall questionnaire, CHF cases were recorded and sorted based on sodium intake.

Results: Over an average of 19 years follow-up, overweight subjects in the highest sodium intake category (113.6 mmol/day or more) were 1.43 times more likely to suffer CHF than overweight individuals with the lowest intakes (50.2 mmol/day or less). Sodium intake was not linked to CHF in normal-weight subjects.

The authors note that a "moderately low" intake of sodium of less than 2,400 mg/day is recommended by several government health agencies, because high sodium intake can also increase hypertension and cardiovascular-disease risks. This study demonstrates a link between sodium and CHF in overweight patients.

Low Sodium=High Mortality?

Population-wide restrictions of dietary sodium have been recommended, yet little evidence has shown a direct link between sodium intake and mortality. An observational study on the relationship of sodium intake to all-cause and cardiovascular disease in the general population found an inverse association of salt intake and mortality.

After adjustment for age and sex, the mortality rate from any cause was highest among those who reported the lowest sodium intake and lowest among the group with the highest sodium intake. Results showed significant differences across the four quartiles of sodium intake in mean age; blood pressure; body-mass index (women only); use of table salt; and history of cardiovascular disease or hypertension. Sodium and calorie intakes were closely related.

These findings do not justify any particular dietary recommendation, but may be valuable in relating sodium intake to mortality rather than an intermediate variable (i.e., blood pressure). The relationship of low vs. high levels of sodium to survival may be significant, but must be considered within the dietary context.

DIET/Fruit and Vegetable

Teach Your Patients About Adequate Fruit and Vegetable Consumption

Increased consumption of fruits and vegetables is thought to increase health and reduce risk for cancer and cardiovascular disease. This trial was designed to quantify the impact of nutritional counseling vs.

behavioral dietary counseling on fruit and vegetable consumption in 271 patients at an inner-city health center. Patients randomized to the first intervention group received education about the importance of increasing fruit and vegetable consumption, with emphasis on how the biological elements of nutrients work to optimize health. Key to this intervention was the "five a day" recommendation - five servings of fruits and vegetables daily. Behavioral counseling was based on social learning theory and the "stage of change" model, which links positive behavior change with emotional readiness. To this end, each patient received personalized, specific advice tailored toward setting short- and long-term goals with regard to fruit and vegetable consumption.

Both interventions were performed by research nurses; all counseling sessions were audiotaped to ensure the two types of counseling remained distinct. Main outcome measures, assessed at baseline, eight weeks and one year, included self-reported daily fruit and vegetable intake (number of portions); plasma concentrations of alphatocopherol, beta-carotene and ascorbic acid; and 24-hour urinary potassium excretion, which are also markers associated with fruit and vegetable consumption.

Behavioral and nutritional counseling resulted in increases in fruit and vegetable consumption after 12 months, but more significantly in the behavioral group: 1.49 additional portions daily vs. 0.87 additional portions daily. The percentage of participants adhering to the "five a day" maxim also increased dramatically (42% vs. 27%, respectively). Moreover, plasma concentrations of beta-carotene and alphatocopherol increased in both groups. (Plasma beta-carotene more than doubled in both groups, while plasma alphatocopherol increased by 33% in the behavioral group vs. 28% in the nutrition group.)

The authors conclude that both interventions are feasible in primary care settings and could be adapted for group administration. They also note that because their findings involved individuals drawn from a low-income population (where fruit and vegetable intake is relatively low compared to higher-income populations), such interventions "may help address socioeconomic inequalities in health."

Tomatoes Lessen Prostate Cancer Risk

Tomatoes and tomato products are excellent sources of lycopene, an antioxidant with potent cancer-fighting abilities. Specifically, lycopene is believed to significantly reduce a man�s odds for prostate cancer.

Although studies have suggested preventive properties of these carotenoids, the data are inconclusive.

Following up on a previous six-year study, the authors of this study gathered data from the Health Professionals Follow-up Study of 40- to 75-year-old (at the 1986 baseline) health practitioners. A food-frequency questionnaire was completed by 47,365 subjects; food contributors to lycopene intake included tomatoes and tomato sauces (such as pasta sauce and salsa); pizza; watermelon; and grapefruit. Subjects were followed for an additional six years (1992 to 1998) for prostate cancer cases.

Consuming tomato sauces, which are considered the best source of bioavailable lycopene, more than twice per week reduced the odds for prostate cancer by 23%, compared to consuming them less than once per month. A higher estimated lycopene intake from all foods was also associated with a significant reduction in prostate cancer risk.

The authors conclude that these data confirm previous reports of a reduced risk for prostate cancer through consuming tomato products and other sources of lycopene. Tomato-product intake is recommended, and is consistent with other general dietary guidelines promoting high fruit and vegetable intake.

Grape Juice Helps Regulate Cholesterol

Moderate alcohol consumption induces increased high-density lipoprotein cholesterol formation and inhibited platelet aggregation. Some studies suggest that these benefits confer primarily to consumption of red wine rather than beer or other types of alcohol.

Flavanoids, the powerful antioxidants present in red wine, are also present in purple grape juice, an observation that spurred this study involving 15 adults with angiographically documented coronary artery disease (CAD). Subjects consumed approximately 21 ounces of purple grape juice twice daily for 14 consecutive days. Flow-mediated vasodilation (FMD), a measure of arterial dilation, was measured

using high-resolution ultrasonography, and susceptibility to increased low-density lipoprotein (LDL) oxidation was also measured.

Data indicated impaired FMD at baseline and increased FMD following ingestion of grape juice. Decreased susceptibility to LDL oxidation was also noted with consumption of grape juice. The authors conclude: "Improved endothelium-dependent vasodilation and prevention of LDL oxidation are potential mechanisms by which flavanoids in purple grape products may prevent cardiovascular events, independent of alcohol content."

Fighting Cardiovascular Disease: Purple Grape Juice as Effective as Wine?

Recent studies have proven that moderate red wine consumption reduces the risk of coronary ischemia and provides antioxidants that protect against cardiovascular disease. Researchers wanted to know if these same benefits could be provided by the consumption of purple grape juice, without the effects of alcohol.

The purpose of this study was to determine the effects of purple grape juice on blood platelet function and the production of nitric oxide, a factor associated with inhibiting cardiovascular disease.

The method involved an in vitro test, in which blood samples were incubated with juice, and a clinical evaluation using 20 subjects. The subjects, aged 20 to 45, were given purple grape juice for 14 consecutive days to confirm the relevance of previous results.

The study found that aggregation (blood clotting) was inhibited and nitric oxide production increased, thereby increasing antioxidant effects in both the in vitro and human subject samples. Results were dose-dependent: when more purple grape juice was administered to a subject, the effects of the juice were enhanced.

The findings of this study indicate that it is possible to obtain the health benefits of red wine without having to consume alcohol. The beneficial properties in both red wine and purple grape juice appear to come from the presence of flavonoids, which are concentrated in the skins, seeds and stems of purple grapes. 

Not Enough Fruits and Vegetables on the Table

Substantial evidence suggests that consistent consumption of fruit and vegetables may prevent cancer and other chronic diseases. Current U.S. dietary guidelines recommend daily consumption of five servings of fruits and vegetables, but whether or not these guidelines translate into actual dietary trends among U.S.

adults remains unclear.

This study evaluated fruit and vegetable consumption in 16 states from 1990-1996. Data from telephone surveys, including questions on dietary intake and participation in leisure-time physical activities, were used to stratify respondents based on various sociodemographic and health-related characteristics.

Results indicated that only 22% of the study population reported adequate intake of fruits and vegetables over the six-year period (19% in 1990, 22% in 1994, and 23% in 1996). The proportion increased among those participating in leisure-time physical activity and those with normal weight, but remained almost the same among inactive people, and dropped among the obese.

The authors note that progress in fruit and vegetable intake over the study period was "encouraging." However, the relatively insignificant change from 1994-1996 emphasizes the need for increased education efforts, particularly targeting those people who are overweight and/or participate in little or no physical activity.

Broccoli Compound May Suppress Growth of Breast Cancer Cells

Sulforaphane is a chemical compound abundant in green vegetables such as broccoli and brussel sprouts. Previous research has shown that sulforaphane can inhibit the growth of cancerous tumors in animals, and can induce apoptosis, or programmed cell death, in colon cancer cells.

A new study published in the Journal of Nutrition suggests that sulforaphane may also slow the spread of breast cancer cells.

In the study, researchers treated samples of a malignant tumor in a laboratory setting with various concentrations of a sulforaphane solution (SUL). The cells were observed every few hours to determine rates of mitosis, or cellular division. The scientists found that within 48 hours, sulforaphane "inhibited cell proliferation" and "induced significant inhibiation of DNA synthesis" in the tumor cells. It appeared to do so by disrupting the action of certain protein microtubules in the cells, which are vital for successful cell division.

The scientists concluded that their study "is the first to report the effectiveness of SUL as an inhibitor of human mammary carcinoma proliferation and to provide confirmatory evidence of a recently identified novel mechanism of SUL action." They recommended that future studies be conducted "to ascertain the implications of SUL intake as a result of either the consumption of cruciferous vegetables in the diet or potential chemoprevention strategies directed toward persons deemed to be at high risk for developing malignancy."

Minerals/Vitamins

Zinc Shown to Reduce Cold Symptoms

The most frequent cause of the common cold is rhinovirus infection, although as many as 200 other viruses may be responsible for the condition. U.S. adults and children suffer from 2-6 colds per year, with substantial loss of work resulting and no proven treatment identified.

The authors of this study note 10 previous controlled trials on treatment of the common cold with zinc lozenges.

n those trials, five reported that zinc lozenges reduced the duration of cold symptoms. The remaining five showed no effect of zinc on cold symptoms, although the authors of the current study suggest that inappropriate zinc lozenge preparations in these latter five studies may have caused the results observed.

In this study, 50 volunteers were recruited within 24 hours of developing symptoms of the common cold. They were administered one zinc lozenge (12.8 mg zinc acetate) or placebo every two to three hours as long as they experienced symptoms. Symptom scores for sore throat; nasal discharge and congestion; sneezing; cough; scratchy throat; hoarseness; muscle ache; fever; and headache were recorded daily for 12 days.

Administration of zinc lozenges reduced duration and severity of cold symptoms compared with placebo. Duration of cold symptoms was 4.5 days in the zinc group vs. 8.1 days in the placebo group; cough duration was 3.1 days vs. 6.3 days; and nasal discharge was 4.1 days vs. 5.8 days. Overall, severity scores for all symptoms were reduced with zinc administration compared to placebo. The authors note that plasma levels of zinc increased and plasma levels of proinflammatory cytokines decreased, suggesting that zinc's influence on cytokines may account for improvements in clinical cold symptoms.

Calcium, Magnesium, Potassium, and Stroke Risk

Hypertension is a strong risk factor for stroke. Evidence that mineral intake, specifically calcium, potassium and magnesium, may help regulate blood pressure suggests that these minerals could also play a role in preventing or reducing the risk of stroke.

In a study involving 85,764 women (34-59 years of age and free of diagnosed cardiovascular disease or cancer), subjects completed dietary questionnaires from which calcium, potassium and magnesium intakes were calculated.

These questionnaires were administered every two years for 15 years, during which time newly diagnosed major illnesses or events (including stroke) were identified and recorded.

Results revealed 690 incident cases of stroke; women with high calcium, potassium and magnesium intake over the course of the study period showed a reduced incidence of stroke compared with women with lower average intake of these minerals. The association was particularly strong with respect to magnesium intake after adjusting for other cardiovascular risk factors.

Interestingly, further adjustment for potassium and magnesium suggested an independent association of calcium with stroke risk, although intakes 600 mg/day did not appear to reduce the risk of stroke further, and the increase in risk was limited to the lowest intake group.

This is a well-executed study; however, clinicians should consider the authors warning that women in this group may have had unknown characteristics predisposing them to stroke. 

Calcium vs. Colorectal Adenomas

Health care professionals and much of the general public are aware that a diet rich in vegetables and fruits is associated with lower risk of colorectal cancer. They also know that eating too much animal fat and red meat seems to increase risk.

This study aimed at identifying what role calcium might play in the biological mechanisms underlying how such cancer may be caused or prevented.

This was a randomized, double-blind trial of 930 subjects (mean age 61; 72% men) with a recent history of colorectal adenomas. The subjects received either calcium carbonate or a placebo daily and got follow-up colonoscopies one year and four years later. Results showed that those who received calcium supplements had a lower incidence of recurrence of adenomas. The results were consistent with epidemologic data and are supported by a large body of experimental data on humans and animals.

Conclusions: Taking calcium carbonate may significantly-though moderately-reduce the risk of recurrent colorectal adenomas. And since the toxicity of this simple and inexpensive supplement is minimal and it may have other benefits (such as reducing the risk of osteoporosis), "its risk-benefit balance may be favorable." 

Do Zinc Lozenges Reduce Cold Symptoms?

No consistently effective therapy for the common cold has been well-documented, but evidence suggests that several possible mechanisms may make zinc an effective option. This study of 100 patients presenting with symptoms of the common cold tested the reliability of zinc lozenges in reducing the duration of cold-related symptoms.

Patients received one lozenge every two hours containing either 13.3 mg of zinc from zinc gluconate, or 5% calcium lactate pentahydrate (placebo).

The average time to complete resolution of symptoms was significantly shorter in the zinc group than in the placebo group (4.5 days compared with 7.5 days). The zinc group experienced significantly fewer days with coughing (2.0 days compared with 4.5 days), headache (2.0 days vs. 3.0 days), hoarseness (2.0 days vs. 3.0 days), nasal drainage (4.0 days vs. 7.0 days), and sore throat (1.0 days vs 3.0 days).

Patients in both the zinc and the calcium group experienced side effects (nausea, bad-taste reactions) from the lozenges; substantially more patients in the zinc group reported side effects than in the calcium group (90% vs. 62%). Doctors should take these potential side effects into consideration when recommending a course of care.

Vitamin E

Preventing Allergies with Vitamin E

Although several environmental influences, including diet, appear to contribute to allergies (asthma, rhinitis and hayfever), the specific relationship between diet and objective markers of disease has not yet been determined.

Because evidence from animal studies suggests that vitamin E reduces IgE (the allergy-related antibody) responses to allergic stimuli, the authors of this study investigated whether high vitamin E intake is associated with lower IgE serum levels and a reduced frequency of allergen skin sensitization in humans.

Data were derived from a random sample of 2,633 adults (18-70 years old). Subjects reported any history of asthma or hayfever symptoms and completed food frequency questionnaires, providing estimates of dietary intake of vitamin E, vitamin C, magnesium, polyunsaturated fats, and other nutrients. Study participants were also tested for skin sensitivity to various allergens, including grass, pollen and cat fur, and serum IgE levels were measured.

Results showed that increased intake of vitamin E reduced serum IgE levels; this relationship proved incremental, such that each one-milligram increase (up to seven milligrams per day) reduced antibody levels by more than five percent. No additional benefit was noted with daily intake higher than seven milligrams. The authors recommend additional research to investigate the potential utility of vitamin E in the primary and secondary prevention of asthma and allergies.

Vitamin E Protects the Prostate

A Finnish study of 29,133 male smokers, aged 50 to 69, found that the incidence of prostate cancer, as well as the mortality rate from the disease, was significantly reduced among those participants who took vitamin E supplements.

Patients followed one of four daily regimens:

* 50 mg of vitamin E;
* 20 mg of beta-carotene;
* both supplements in combination; or
* an inactive pill.

The incidence of prostate cancer diagnosis was 32% lower among men who took vitamin E alone or in combination with beta-carotene. Additionally, the death rate from the disease was 41% lower among those same patients. This observation suggests that vitamin E may have the potential to prevent one of the most common and deva

Vitamin/ Supplements

Vitamin C

High Vitamin C Levels May Affect Risk of GI Disorders

Evidence suggests that low levels of ascorbic acid in the blood may increase the risk of several gastrointestinal disorders, including peptic ulcers and gastric cancer. Chronic infection with theHeliobacter pylori bacteria - particularly a strain known as cagA - may also contribute to gastric cancer and peptic ulcers.

Some research suggests that H. pyloriand ascorbic acid concentrations are not related, but these studies had small sample sizes. Prior to the current study, no large-scale studies had examined the relationship between blood ascorbic acid and H. pylori levels.

Researchers tested blood samples of 6,746 adults enrolled in the Third National Health and Nutrition Examination Survey. Of the test subjects, 32% tested positive for H. pylori; of those, 54% had the cagA strain. The gender, percentage of current cigarette smokers and self-reported use of NSAIDs were similar among those who tested positive for H. pylori and those who tested negative.

Analysis of the blood samples revealed that ascorbic acid rates were inversely related to the prevalence of H. pylori. In patients whose serum ascorbic levels were 0.35 milligrams or less, the infection rate with H. pylori was 37.2%. For patients with serum ascorbic levels of 0.36 or higher, the infection rate dropped to 30.8 percent, even after adjusting for variables such as age, race, body mass index, physical activity level, use of aspirin or NSAIDs, and cigarette smoking. This finding was statistically significant. In Caucasian subjects, the analysis found that a 0.5 milligram increase in blood ascorbic acid levels was associated with a 31 percent decrease in the prevalence of the cagA strain of H. pylori.

The researchers concluded: "Serum ascorbic acid is significantly correlated with seropositivity to both H. pylori and to the pathogenic cagA-positive strain of H. pylori among white Americans. To our knowledge, this report is the first

population-based study of Americans to report such associations. If these findings are confirmed by other investigators and are linked causally, higher intakes of ascorbic acid may be a protective factor in the prevention of H. pylori infection." 

More Evidence that Vitamin C Helps Cold/Flu Symptoms

The U.S. recommended daily allowance of vitamin C is 75 mg for an adult man and 70 mg for an adult woman, although popular literature often suggests much higher doses as a means of treating respiratory infections.

Whether megadoses of vitamin C are effectively absorbed by the body or are passed off in the urine, as is the case with most water-soluble vitamins, has long been debated.

This study observed 252 students for 10 days to see if cold or flu symptoms were different between students receiving high doses of vitamin C compared to a control group. Subjects reporting symptoms received hourly doses of vitamin C (1,000 mg) for the first six hours, then three times daily there after. Subjects not reporting symptoms received 1,000-mg doses three times daily. A control group of 463 students also participated and were administered pain relievers and decongestants when necessary.

Methods of recording baseline data from subjects were different between groups; those in the control group were not asked whether or not they had cold or flu symptoms, while the vitamin C group patients were. Observation of the data demonstrates that reported overall flu and cold symptoms may decrease faster in those who take megadoses of vitamin C compared to a control group.

This study provokes many interesting questions. However, before substantial conclusions can be made, more rigorous patient handling and statistical methodologies will need to be implemented. For example, no statistical analyses were conducted to assess whether or not the two groups were dissimilar prior to the study, nor were the observed differences between the groups after the study statistically checked to see if they were due to chance alone. 

New Vitamin C Recommendations

This paper alerts health care professionals to the news that the Food and Nutrition Board of the National Academy of Sciences is revising its recommendations for vitamin C intake. The revision is required because since the current 60 mg recommended daily allowance (RDA) was set in 1989, extensive new biochemical, molecular, epidemiologic, and clinical data have become available.

The board will base its new recommendations (expected to be less than 1 g daily) on some or all of the following criteria to determine the estimated average requirement (EAR) in order to compute a specific RDA:

* dietary availability;
* steady-state concentrations in tissues relative to dose;
* bioavailability,
* urine excretion,
* adverse effects,
* biochemical and molecular function relative to vitamin concentration
* direct beneficial effects and epidemiologic observations relative to dose,
* prevention of deficiency.

Conclusions: "If the estimated average requirement (EAR) cannot be determined, an adequate intake (AI) amount is recommended instead of an RDA.

The AI was estimated to be either 200mg/d from

5 servings of fruits and vegetables or 100mg/d of vitamin C to prevent deficiency with a margin of safety." 

Vitamin C Influences Blood Lead Levels

In an effort to prevent lead toxicity, the Centers for Disease Control and Prevention (CDC) has developed screening programs to identify childhood blood lead levels. Among adults, work-related lead exposure has been targeted as an area of concern by the Occupational Safety and Health Administration.

As part of these efforts, data gathered from the Third National Health and Nutrition Examination Survey (1988-1994) was utilized in a study that evaluated the relationship of ascorbic acid (vitamin C) to blood lead levels. The study compared vitamin C intake (as evidenced by serum ascorbic acid levels) and blood lead levels in 4,213 children (age 6-16) and 15,365 adults (age 17 or older), with the results presented as follows:

* Children with the highest vitamin C intake were 89% less likely to have elevated blood lead levels compared with youths with the lowest intake.

* Adults with the highest vitamin C intake were 65-68% less likely to have elevated blood lead levels compared with adults with the lowest intake.

These findings suggest that high levels of ascorbic acid are independently associated with decreased incidence of elevated blood lead levels. The authors note that "if a causal relationship is confirmed, higher intakes of ascorbic acid may have public health implications for the prevention of lead toxicity."

Vitamin C Is in Your Brain

The blood-brain barrier is a fortress of blood vessels which forms a protective barrier between the blood and the brain. Researchers are studying vitamin C absorption in the brain to determine why it is present and at higher concentrations than any other area of the body.

Unlike many other substances which are screened out by the blood-brain barrier, vitamin C crosses as dehydroascorbic acid and is retained as ascorbic acid in the brain. These findings indicate that increasing the blood level of dehydroascorbic acid can potentially increase vitamin C concentrations in the brain.

Vitamin C has antioxidant properties which may slow the progression of moderately severe Alzheimer�s disease, and its role as a free-radical scavenger may help prevent other diseases. 

Vitamin C Helps Lung Function?

Chronic obstructive pulmonary disease (COPD) is a major cause of death and disability among adults throughout the world. Cigarette smoking is a principal risk factor, but only 15 percent of smokers develop COPD, which suggests other factors may contribute to susceptibility.

The data for this study were collected in 1989 in 69 rural counties in China.

Within each county, 120 subjects aged 35-64 years underwent pulmonary function testing, completed a detailed questionnaire and provided blood samples.

Among the 3,085 subjects for whom there were complete data, dietary intake of vitamin C was significantly related to protection against the loss of pulmonary function. The magnitude of the association between vitamin C intake and lung function equaled approximately one year of age-related decline in lung function for every 100-mg/day decrease in vitamin C intake. This association was observed among individuals and when comparing counties, and it held true for both dietary vitamin C and plasma vitamin C data.

A long-term study is needed to gauge the effect of vitamin C over time and its role in protecting the lung against age-related changes in pulmonary function.

Vitamin C Favorably Alters Cholesterol Levels

Elevated lipoprotein levels (levels of protein/fat compounds in blood plasma) contribute directly to the buildup of cholesterol in the bloodstream. A study of 10 women examined the effects of vitamin C (ascorbic acid) supplements on plasma lipoprotein levels.

Subjects were supplemented with 1000 mg of vitamin C daily for four weeks. Vitamin C concentrations were significantly higher in blood plasma after two and four weeks of supplementation compared with baseline; levels appeared to peak after two weeks and were maintained through the four-week mark. Plasma concentrations of low-density lipoprotein cholesterol (LDLC) were found to be 16% lower at four weeks compared with baseline, and although high-density lipoprotein cholesterol (HDLC) levels did not change significantly with vitamin C supplementation, the minimal reduction in HDLC was positively associated with the increase in plasma vitamin C levels.

These findings parallel previous studies in suggesting that increases in vitamin C intake may favorably alter lipoprotein levels and thus reduce the risk of heart disease and other cholesterol-related disorders. 

Vitamin Supplements 

Vitamin Supplements May Lower Cataract Risk

Cataracts are a common problem among older Americans, a population expected to triple in the next 50 years. Certain dietary components, particularly vitamins and minerals that protect against oxidative stress, may play a role in retarding cataract development.

Additionally, results of several cross-sectional studies provide evidence of a lower incidence of lens opacities among users of various types of nutritional supplements.

This recent population-based study provides further evidence of the association between vitamin supplement use and reduced incidence of nuclear and cortical cataracts. The participants of the study included 43- to 86-year-old residents of Beaver Dam, Wisconsin, identified by private census. The five-year incidence of cataracts, determined by optometric photographic techniques, was evaluated at baseline and follow-up examination. Of the 3,684 participants in the examinations, 3,089 qualified for incident cataract analysis in the current study.

At five-year follow-up, subjects who had used multivitamins or any supplement containing Vitamin C or E for more than 10 years were 60 percent less likely to suffer cataracts compared with nonusers. Taking multivitamins for this duration lowered the risk for nuclear and cortical cataracts, but not for subcapsular cataracts. Intake of supplements for shorter durations than 10 years was not associated with reduced risk for cataract. Differences in lifestyle and diet between supplement users and nonusers did not influence these associations.

The authors caution that no specific nutrient appeared to be responsible for this reduced risk, and that unmeasured lifestyle differences between supplement users and nonusers may have contributed to their results.

Thiamine in the Treatment of Hepatitis B

Chronic hepatitis B virus (HBV) is an international health concern that causes cirrhosis, liver cancer, liver failure, and death. Most current treatments for HBV are expensive and posses physical and psychological side effects.

A relationship between a relative deficiency in thiamine (vitamin B-1) and chronic HBV infection is suggested in three major areas. One is that thiamine may possess antiviral properties. Second, some research supports the thought that thiamine may slow or reverse liver damage during chronic HBV. Third, correlation exists between thiamine deficient populations and the prevalence of chronic HBV.

With this background, the purpose of the present study was to present the results of administering thiamine to three patients with chronic HBV. One marker of HBV is the level of aminotransferase found in the body. The authors noted that after and during periods of thiamine administration to the three patients that their aminotransferase levels dropped substantially, which is associated with the amelioration of HBV. When the thiamine was removed from the patients, aminotransferase levels rose again.

These cases demonstrate that the relationship between thiamine and HBV needs to be further investigated because of its potential utility. If proven effective in reducing liver damage or inducing remission of chronic HBV in larger trials, thiamine may offer obvious advantages over current treatments for chronic HBV.

B-6 Deficiencies May Increase Risk of Heart Disease

As much as one-fifth of the U.S. population may be at increased risk because they do not get enough vitamin B-6. This study links vitamin B-6 deficiencies to heart disease and stroke. Vitamin B-6 levels were lower in both men and women who had heart disease or stroke incidence compared to healthy subjects, and subjects with a B-6 deficiency were also more than twice as likely to have heart disease or stroke than those without a deficiency

Overall about 20 percent of the individuals in the study were found to have B-6 deficiencies. These findings were independent of homocysteine levels, which have been previously used as an indicator of heart attacks and strokes. A more detailed analysis of the B-vitamins� independent effects on cardiovascular disease is needed.

Red Palm Oil Increases Vitamin A Levels

When it comes to what's on the minds of children these days, vitamins definitely are not at the top of the list. In our fast-forward way of life, the simplest things, such as taking a daily vitamin, can sometimes even evade parents.

According to the World Health Organization, 140 to 250 million children under the age of five are affected by vitamin A deficiency. No matter what the reasons, kids aren't getting enough of these important nutritional supplements. In a year-long study of African school children, researchers discovered the benefits of adding red palm oil to the daily school lunches to help boost the vitamin A levels in the students.

Red palm oil is the highest plant source of provitamin A carotenoids. In the study, each one of the 239 young volunteers either received 15 ml of red palm oil in their individual meals three times a week, a vitamin A pill with their lunch or neither. Researchers recorded a baseline reading of each child's deficiency level. At the end of the study, 12 months later, a second reading was taken to measure any changes.

The children who ingested the meals with the red palm oil additive saw a 26 percent improvement in their deficiency levels, comparable to the 29 percent improvement for the children who took a vitamin A capsule. According to the authors, the results showed how beneficial the inclusion of red palm oil can be in a child's diet, especially when it may be more cost effective in countries that capsulated supplements may not be as readily available.

Omega-3/NUTRICION

High Levels of Omega-3 Fatty Acids Improve Mood, Behavior Levels

In 2000, the American Heart Association revised its Dietary Guidelines to recommend that people eat at least two servings of fatty fish per week as a means of reducing the risk of cardiovascular disease.

While the cardioprotective effects of omega-3 fatty acids are well-established, other studies have demonstrated that omega-3 fatty acids may be linked to a variety of psychological conditions, including major depression and bipolar disorder. Research presented at a recent meeting of the American Psychosomatic Society has strengthened this link, with the results of small trial suggesting that low blood levels of omega-3s may have a negative impact on a person's mood and behavior.

In the study, researchers collected blood samples of 106 hypercholesterolemic people who had no history of depression or any other diagnosed mood disorder, and did not take fish oil supplements or psychotropic drugs. In addition to blood tests, all subjects completed a series of tests designed to measure mood, personality and levels of impulsive behavior.

Participants with low blood levels docosahexaeonic acid (DCA) were 42 percent more likely to report symptoms of mild to moderate depression, while patients with low levels of eicosapentaenoic acid (EPA) were more likely to be in a negative mood, and were associated with high neuroticism scores. Low levels of alpha-linolenic acid (ALA) were associated with higher levels of impulsive behavior.

"In conjunction with published research, these data suggest that dietary intake of omega-3 fatty acids may be a determinant of normative variability in affect regulation, impulse control and personality," the authors wrote in their conclusion. They added, "This study opens the door for future research looking at what effect increasing omega-3 intake - whether by eating omega-3-rich foods like salmon or taking fish oil supplements - has on people's moods."

Omega-3 Supplementation May Reduce Heart Rate, Cardiovascular Events

Several randomized controlled trials and epidemiologic studies have demonstrated the cardioprotective effects of omega-3 fatty acids, in particular docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

While these fatty acids are believed to decrease susceptibility to heart arrythmia, it remains unclear as to whether this effect is mediated by direct cardiac mechanisms or classic risk factors.

In this randomized, double-blind, placebo-controlled trial, 18 white men with a history of myocardial infarction were randomized to receive three capsules containing a total of 810 milligrams of omega-3 fatty acids (585 mg of DHA and 225 mg of EPA) per day or identical placebo capsules for two four-month periods in a crossover design. At the end of each period, heart rate (HR), heart rate variability, and heart rate recovery after exercise were determined, along with effects on arterial compliance, blood pressure, cardiac function and other measurables.

"Our principle findings were that omega-3 fatty acids significantly decreased HR at rest, accelerated the return to a normal HR after standing and exercise, and increased HR variability," the researchers stated. Omega-3 fatty acid supplementation decreased resting heart rate from an average of 73 beats per minute to 68 beats per minute. In addition, omega-3 supplementation was associated with a 19 percent decrease in heart rate one minute after exercise, which was accompanied by "appropriate increases in stroke volume and ejection times."

Conclusion: "A high HR at rest (especially in men) has been strongly linked to cardiovascular events, including mortality. The decrease in HR noted in the present study is in the same range as that observed with beta-blocker therapy, another intervention that has been shown to decrease risk of sudden death. A recent meta-analysis has associated a small but significant decrease in HR with increased omega-3 fatty acid intakes. Our observations extend these findings and suggest that modulation of HR can be achieved in patients with known coronary heart disease who consume recommended amounts of EPA plus DHA."