Large Amounts of Vitamin C Increase Risk of Kidney Stones

Men who consume high levels of vitamin C are at twice the risk of kidney stones than men who do not.

In the current study, published in JAMA Internal Medicine, the investigators followed over 23,000 Swedish men who were between 45 and 79 years old in 1997 up to the year 2009. None of them had kidney stones at baseline.

Close to 900 of the men took 1,000-milligram doses of vitamin C, and 3 percent of them (31 men) later had kidney stones. Less than 2 percent of those in the rest of the group developed kidney stones.

The researchers adjusted for factors which could undermine the reliability of the findings, such as education levels, ages, and body weights.

They revealed that those men who received the high-dose supplements had an elevated kidney stone risk ranging between 1.7 and 2.2 times.

The authors point out that there are no significantly proven reasons for any person to take such large amounts of vitamin C. The results of the study do not apply to vitamin C that comes from food.

Another outcome of the study was that multivitamin supplements that don't have large doses of vitamin C did not increase the risk of kidney stones.

The authors point out that more studies are needed to back up these findings, and they emphasize that people should not stop consuming vitamin C after reading this report. If you are concerned about your vitamin C intake or any health consequences related to vitamin supplementation, talk to your doctor.

Last year, a study presented at the Endocrine Society's 94th Annual Meeting in Houston, revealed that vitamin C and vitamin D supplements are associated with high calcium levels in the urine and blood,. High urine/blood calcium levels are linked to a higher risk of kidney stones.

Sunlight may help ward off rheumatoid arthritis in women

Use of sunblock could lessen protective effects, suggest authors

[Exposure to ultraviolet-B and risk of developing rheumatoid arthritis among women in the Nurses' Health Study Online First doi 10.1136/annrheumdis-2012-202302]

Regular exposure to sunlight—specifically ultraviolet B (UVB)—may reduce the risk of developing rheumatoid arthritis, indicates a large long term study published online in the Annals of the Rheumatic Diseases.

But the effect of UVB exposure was only evident among older women, possibly because younger women are more aware of the hazards of sunlight and so cover up with sun block, suggest the authors.

They base their findings on participants in two phases of the US Nurses' Health Study (NHS), the first of which has tracked the health of more than 120,000 nurses since 1976, when they were aged between 30 and 55, until 2008.

The second (NHSII) has tracked the health of a further 115,500 nurses since 1989, when they were aged between 25 and 42, until 2009.

Rather than simply relying on geography to quantify likely levels of UVB exposure, the researchers used a more sensitive assessment, known as UV-B flux, which is a composite measure of UVB radiation, based on latitude, altitude, and cloud cover.

It is measured in R-B units: a count of 440 R-B units over 30 minutes, for example, is sufficient to produce slight redness in untanned white skin.

Exposure was then estimated according to the US state of residence, and ranged from an annual average of 93 in Alaska and Oregon to 196 in Hawaii and Arizona. Likely estimates of UV exposure at birth and by the age of 15 were also included.

Over the study period, 1314 women developed rheumatoid arthritis. Among nurses in the first NHS cohort, higher cumulative exposure to UVB was associated with a reduced risk of developing the disease.

Those with the highest levels of exposure were 21% less likely to develop rheumatoid arthritis than those with the least, the analysis showed.

This backs up the findings of other studies, showing a link between geography and the risk of rheumatoid arthritis as well as other autoimmune conditions, including type 1 diabetes, inflammatory bowel disease, and multiple sclerosis, say the authors.

But no such association for UV-B exposure was found among women in NHSII. These women were younger than those in the first NHS, and so might have been more savvy about the potential hazards of acquiring a tan, suggest the authors.

"Differences in sun protective behaviours (eg greater use of sun block in younger generations) may explain the disparate results," they explain.

They add that it is unclear at what stage of life the protective effect of UV-B occurs. Many of the study participants didn't move house between birth and their teens, and there was no difference in the results for these time points.

But they conclude: "Our study adds to the growing evidence that exposure to UV-B light is associated with decreased risk of rheumatoid arthritis. The mechanisms are not yet understood, but could be mediated by the cutaneous production of vitamin D and attenuated by use of sunscreen or sun avoidant behaviour."

High supplemental calcium intake may increase risk of cardiovascular disease death in men

A high intake of supplemental calcium appears to be associated with an increased risk of cardiovascular disease (CVD) death in men but not in women in a study of more 388,000 participants between the ages of 50 and 71 years, according to a report published Online First by JAMA Internal Medicine, a JAMA Network publication.

Calcium supplementation has become widely used, especially among the elderly population, because of its proposed bone health benefits. However, beyond calcium's established role in the prevention and treatment of osteoporosis, its health effect on nonskeletal outcomes, including cardiovascular health, remains largely unknown and has become "increasingly contentious," the authors write in the study background.

Qian Xiao, Ph.D., of the National Cancer Institute, Bethesda, Md., and colleagues examined whether the intake of dietary and supplemental calcium was associated with mortality from total CVD, heart disease and cerebrovascular diseases. The study participants were 388,229 men and women ages 50 to 71 years from the National Institutes of Health-AARP Diet and Health Study in six states and two metropolitan areas from 1995 through 1996.

"In this large, prospective study we found that supplemental but not dietary calcium intake was associated with an increased CVD mortality in men but not in women," the authors conclude.

During an average 12 years of follow-up, 7,904 CVD deaths in men and 3,874 CVD deaths in women were identified and supplements containing calcium were used by 51 percent of men and 70 percent of women. Compared with non-supplement users, men with an intake of supplemental calcium of more than 1,000 mg/day had an increased risk of total CVD death (risk ratio [RR], 1.20), more specifically with heart disease (RR, 1.19), but not significantly with cerebrovascular disease death (RR, 1.14).

For women, supplemental calcium intake was not associated with CVD death, heart disease death or cerebrovascular disease death. Dietary calcium intake also was not associated with CVD death in men or women.

"Whether there is a sex difference in the cardiovascular effect of calcium supplement warrants further investigation. Given the extensive use of calcium supplement in the population, it is of great importance to assess the effect of supplemental calcium use beyond bone health," the authors conclude.

TV viewing, exercise habits may significantly affect sperm count

20 hours of TV weekly may nearly halve sperm count; 15 or more hours of moderate to vigorous exercise weekly may boost sperm count

Men's sperm quality may be significantly affected by their levels of physical activity, according to a new study led by researchers at Harvard School of Public Health (HSPH). They found that healthy young men who were sedentary, as measured by hours of TV viewing, had lower sperm counts than those who were the most physically active.

"We know very little about how lifestyle may impact semen quality and male fertility in general so identifying two potentially modifiable factors that appear to have such a big impact on sperm counts is truly exciting," said lead author Audrey Gaskins, a doctoral student at HSPH.

The study will be published online February 4, 2013 in the British Journal of Sports Medicine.

Gaskins and her colleagues analyzed the semen quality of 189 men between the ages of 18 to 22 participating in the Rochester Young Men's Study during 2009 at the University of Rochester. The men were asked about their physical activity and TV-watching habits, in addition to health issues that may affect their sperm quality, such as diet, stress levels, and smoking.

Results showed that men who watched more than 20 hours of TV weekly had a 44% lower sperm count than those who watched almost no TV. Men who exercised for 15 or more hours weekly at a moderate to vigorous rate had a 73% higher sperm count than those who exercised less than 5 hours per week. Mild exercise did not affect sperm quality.

"The majority of the previous studies on physical activity and semen quality had focused on professional marathon runners and cyclists, who reach physical activity levels that most people in the world cannot match. We were able to examine a range of physical activity that is more relevant to men in the general population," said Jorge Chavarro, senior author of the study and assistant professor of nutrition and epidemiology at HSPH.

6 ounces of beef is good for muscles

People tend to lose muscle mass as they age; researchers are investigating ways to delay or counteract age-related muscle loss. A study conducted by the Exercise Metabolism Research Group at McMaster University suggests that current guidelines for meat consumption are based on the protein needed to prevent deficiency without consideration for preservation of muscle mass, particularly for older individuals who are looking to maintain their muscle as they age. This research was published in the journal Applied Physiology, Nutrition, and Metabolism.

Thirty-five middle-aged men (~59 years old) participated in a study that found that eating a 6-ounce serving of 85% lean ground beef resulted in significant improvements in the rate of muscle protein synthesis following exercise. The investigators measured muscle protein synthesis (MPS), which is essential to the body’s ongoing growth, repair and maintenance of skeletal muscle in men who did and did not lift weights. What researchers determined was that the quantity of beef needed for optimal MPS for this age group is double the current recommended serving size of meat.

“Canada's Food Guide now suggests that consuming about 3oz (0.80 g/kg/d) of meat per serving is adequate to provide protein at the recommended level,” says Dr. Stuart Phillips, the study’s senior author and a researcher with the Exercise Metabolism Research Group at McMaster University. “However, our work shows that the quantity of beef needed to maximize the renewal of new muscle proteins was at least 6oz in middle-aged men. Our findings have clear ramifications for the current recommendations regarding protein to prevent muscle loss in aging.”

The article “Dose-dependent responses of myofibrillar protein synthesis with beef ingestion are enhanced with resistance exercise in middle-aged men” is available Open Access in the journal Applied Physiology, Nutrition, and Metabolism, DOI: 10.1139/apnm-2012-0092

Low vitamin D levels may increase risk of Type 1 diabetes

Having adequate levels of vitamin D during young adulthood may reduce the risk of adult-onset type 1 diabetes by as much as 50%, according to researchers at Harvard School of Public Health (HSPH). The findings, if confirmed in future studies, could lead to a role for vitamin D supplementation in preventing this serious autoimmune disease in adults. The study was published online February 3, 2013 and will appear in the March 1 print edition of the American Journal of Epidemiology.

"It is surprising that a serious disease such as type 1 diabetes could perhaps be prevented by a simple and safe intervention," said lead author Kassandra Munger, research associate in the Department of Nutrition at HSPH.

This study provides the strongest findings to date to suggest that vitamin D may be protective against type 1 diabetes.

In type 1 diabetes (once called juvenile-onset or insulin-dependent diabetes), the body's immune system attacks and permanently disables the insulin-making cells in the pancreas. About 5% of the estimated 25.8 million people in the United States with diabetes have type 1, according to the American Diabetes Association. Although it often starts in childhood, about 60% of type 1 diabetes cases occur after age 20.

Previous studies have suggested that a shortage of vitamin D might boost type 1 diabetes risk, although those studies mostly examined the link between vitamin D levels in pregnancy or childhood and the risk of type 1 diabetes in children. Other research, in young adults, uncovered an association between high vitamin D levels and a lowered risk of multiple sclerosis—an autoimmune disease genetically and epidemiologically related to type 1 diabetes—suggesting that inadequate vitamin D in adulthood may be an important risk factor for autoimmune diseases in general.

Long-term study of military personnel

The researchers conducted a prospective case-control study of U.S. military personnel on active duty, using blood samples from the Department of Defense Serum Repository, which contains more than 40 million samples collected from 8 million military personnel since the mid-1980s. Identifying 310 individuals diagnosed with type 1 diabetes between 1997 and 2009, the team examined blood samples taken before onset of the disease, and compared the samples with those of 613 people in a control group.

The researchers found that white, non-Hispanic, healthy young adults with higher serum levels (>75 nmol/L) of vitamin D had about half the risk of developing type 1 diabetes than those with the lowest levels of vitamin D (<75 nmol/L). Although the researchers found no significant association among Hispanics and blacks, the authors said this may be due to the small number of individuals in these groups.

"The risk of type 1 diabetes appears to be increased even at vitamin D levels that are commonly regarded as normal, suggesting that a substantial proportion of the population could benefit from increased vitamin D intake," said Alberto Ascherio, professor of epidemiology and nutrition at HSPH, the study's senior author.

About vitamin D

Worldwide, an estimated 1 billion people have inadequate levels of vitamin D in their blood, and deficiencies can be found in all ethnicities and age groups. While sun exposure is an excellent source of vitamin D, sunscreen, clothing, skin pigmentation, and winter months reduce vitamin D production. Food tends to be a poor source of vitamin D, with "good" sources, such as salmon and fortified milk, containing 400IU or less per serving. "Whereas it is premature to recommend universal use of vitamin D supplements for prevention of type 1 diabetes, the possibility that many cases could be prevented by supplementation with 1,000-4,000 IU/day, which is largely considered safe, is enticing," the authors said.

Alcohol + diet drinks may increase intoxication

Alcohol + diet drinks may increase intoxication more than alcohol + regular drinks

A person's breath alcohol concentration (BrAC) after drinking is influenced by factors such as food.

New findings show that mixing alcohol with a diet soft drink can result in a higher BrAC than mixing alcohol with a regular or sugar-sweetened drink.
Individuals were unaware of these differences, which may pose safety risks such as drinking and driving.

An individual's breath alcohol concentration (BrAC) following alcohol intake is influenced by several factors, including food. While it is known that food delays the stomach emptying, thus reducing BrAC, only recently has the role of nonalcoholic drink mixers used with alcohol been explored as a factor influencing BrAC. A new comparison of BrACs of alcohol consumed with an artificial sweetener versus alcohol consumed with a sugared beverage has found that mixing alcohol with a diet soft drink can result in a higher BrAC.

Results will be published in the April 2013 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"More attention needs to be paid to how alcohol is being consumed in the 'real world,'" said Cecile A. Marczinski, assistant professor of psychology at Northern Kentucky University. She referenced an earlier field study of bar patrons. "Researchers found that, one, individuals who reported consuming alcohol with diet beverages had the highest BrACs, as compared to all other bar patrons, and two, that women tended to be more frequent consumers of diet mixers with their alcohol. These good naturalistic observations give researchers many ideas to explore in a controlled laboratory setting."

Dennis L. Thombs, professor and chair of the department of behavioral and community health at UNT Health Science Center, was the author of the field study referenced by Marczinski. "Research on artificially sweetened drink mixers is new," he said. "I believe this might be only the third study published to date on this issue, and the findings are quite consistent with ours."

"I am really interested in drinking and driving as a problem, so I wanted to know if the simple choice of mixer could be the factor that puts a person above or below the legal limit," added Marczinski. "I also wanted to determine if any BrAC difference would be something that subjects would notice, since this has implications for safe drinking practices, including decisions to drive."

Study authors had 16 participants (8 females, 8 males) attend three sessions where they received one of three doses – 1.97 ml/kg vodka mixed with 3.94 ml/kg Squirt, 1.97 ml/kg vodka mixed with 3.94 ml/kg diet Squirt, and a placebo beverage – in random order. The participants' BrACs were recorded, as well as their self-reported ratings of subjective intoxication, fatigue, impairment, and willingness to drive. Their objective performance was assessed using a cued go/no-go reaction time task.

"Alcohol consumed with a diet mixer results in higher BrACs as compared to the same amount of alcohol consumed with a sugar-sweetened mixer," said Marczinski. "The subjects were unaware of this difference, as measured by various subjective ratings including feelings of intoxication, impairment, and willingness to drive. Moreover, their behavior was more impaired when subjects consumed the diet mixer."

When asked why mixing alcohol with a diet drink appears to elevate BrACs, Thombs explained that the stomach seems to treat sugar-sweetened beverages like food, which delays the stomach from emptying. "The best way to think about these effects is that sugar-sweetened alcohol mixers slow down the absorption of alcohol into bloodstream," he said. "Artificially sweetened alcohol mixers do not really elevate alcohol intoxication. Rather, the lack of sugar simply allows the rate of alcohol absorption to occur without hindrance."

Both Marczinski and Thombs were concerned about the risk that diet mixers can pose for alcohol-impaired driving. "In this study, subjects felt the same whether they drank the diet or regular mixed alcoholic beverage," said Marczinski. "However, they were above the limit of .08 when they consumed the diet mixer, and below it when they drank the regular mixed beverage. Choices to drink and drive, or engage in any other risky behavior, often depend on how people feel, rather than some objective measurement of impairment. Now alcohol researchers who are interested in prevention have something new to consider when developing or modifying intervention programs."

Thombs agreed. "Research on alcohol mixers is critically important for improving serving practices in on-premise drinking establishments," he said. "About one-half of all drinking and driving incidents are estimated to occur in persons leaving these settings. This type of research can provide guidance to policy-makers interested in improving the safety of bars and nightclubs."

"We have an obesity crisis in this country," added Marczinski. "As such, individuals tend to be conscious about how many calories they are consuming, and they might think that mixing alcohol with diet drinks is a healthy choice. Yet the average reader needs to know that while mixing alcohol with a diet beverage mixer may limit the amount of calories being consumed, higher BrACs are a much more significant health risk than a few extra calories."

"In natural drinking settings, such as bars and nightclubs, young women are significantly more likely than young men to order drinks mixed with diet cola," said Thombs. "I suspect this occurs because young women tend to be more weight conscious than young men. Thus, from a public health perspective, artificially sweetened alcohol mixers may place young women at greater risk for a range of problems associated with acute alcohol intoxication."