Can you tell how a vitamin is made, or how well it is tested for safety, by reading the label? Can you tell if the dosage listed is accurate or from where came the raw ingredients? After reading through the marketing material that comes on the package, can you tell if there are impurities in the product or if there are potential side effects to the ingredients? Here a New York Times article asks why potentially dangerous supplements remain on store shelves.

Why Dangerous Supplements Linger on Store Shelves

 

By ANAHAD O'CONNOR

April 30, 2014, 8:00 am

 

 

 

Chester Higgins Jr./The New York TimesAbout 55,000 dietary supplements, largely unregulated, are sold in the United States.

The first cases of liver problems linked to a popular weight loss supplement called OxyElite Pro began in Hawaii last May. But it wasn’t until four months later that the Food and Drug Administration, the agency responsible for getting dangerous products off the market, learned of the outbreak, and the product was finally recalled in November.

Flaws in the way that dietary supplements are monitored and reported are causing potentially life-threatening delays in how long dangerous products linger on store shelves, said Dr. Pieter Cohen, an assistant professor at Harvard Medical School who has studied supplement safety problems. They are also, he said, setting the stage for similar episodes to occur again.

Writing in a recent editorial in The New England Journal of Medicine, Dr. Cohen said that one of the more significant problems in such instances is that many cases of harm are reported to doctors and poison control centers but are either delayed in reaching the F.D.A. or do not make it to the agency at all.

“We’ve all been working under the premise that once a dangerous supplement is identified, the F.D.A. will swiftly remove it from the market,” he said. “But what I’ve come to realize over the last several years is that dangerous supplements remain on store shelves sometimes indefinitely or much longer than they should be.”

Many doctors who suspect a supplement has injured a patient neglect to submit a timely report to MedWatch, the online portal that the F.D.A. maintains to help identify clusters of injury linked to harmful products, Dr. Cohen said. He noted that delays occurred in 2008, when local health departments determined that more than 200 people had suffered selenium poisoning from a brand of multivitamin. And it happened in 2011, when the Department of Defense removed a workout supplement from military bases that contained a powerful stimulant known as DMAA.

“It took the F.D.A. an additional 16 months after the military ban to gather sufficient safety data from MedWatch to alert consumers about DMAA’s risks,” he wrote. In all of these cases, he added, “MedWatch reports were irrelevant.”

The F.D.A. has been stepping up efforts to make doctors more aware of the MedWatch system and to encourage them to use it to report promptly any serious reactions to drugs, supplements and other products, said Daniel Fabricant, the director of the division of dietary supplement programs in the agency’s Center for Food Safety and Applied Nutrition.

Even so, he said, doctors sometimes neglect to include critical information in their reports. Often left out are details about the product and its label, the results of any blood work or diagnostic tests, and whether the patient was using any other drugs or supplements, which can make follow-up difficult. Linking a single supplement that might contain dozens of different ingredients to an illness requires a forensic investigation that takes time, he said.

“I certainly understand and share Dr. Cohen’s concern,” Dr. Fabricant said. “But I do think the system has been useful and successful and instrumental in the agency taking action against products that were unsafe.”

Before joining the F.D.A. in 2011, Dr. Fabricant was a top executive at an industry trade group, the Natural Products Association. The F.D.A. recently announced that Dr. Fabricant is leaving the agency this month to return to the trade group as its chief executive.

Dr. Cohen said that many doctors simply do not find the F.D.A. or MedWatch very helpful in dealing with patients who have ingested a tainted product. So instead they turn to poison control centers, which offer medical advice in cases where a patient ingested something toxic. Indeed, in a report last year, the Government Accountability Office noted that from 2008 to 2010, more than 1,000 adverse events related to dietary supplements were reported to poison control centers – but not to the F.D.A.

“Because data are not routinely shared between the centers and the agency,” Dr. Cohen wrote, “the F.D.A. did not have access to these reports.”

Critics of the $32 billion a year supplement industry argue that the F.D.A. is hampered by a federal law that, they say, was written largely to protect the industry, the 1994 Dietary Supplement Health and Education Act.

The law, which gives companies much leeway in how they manufacture and advertise supplements, allows them to put products on the market without F.D.A. approval. As a result, the agency has little power to stop tainted products from landing on store shelves in the first place, even though research suggests that adulteration and mislabeling are widespread.

But industry representatives like Steve Mister, the president and chief executive of the Council for Responsible Nutrition, a supplement trade group, said the problem is not the law but an overstretched F.D.A., which has not aggressively pursued the industry’s bad apples. “The F.D.A. is grossly underfunded, it needs more resources, and Congress can do that,” he said.

Dr. Cohen said that at the very least, Congress should require that supplements carry information about side effects on their packaging.

“Right now, even when we know that a supplement has side effects, there’s no requirement that it appear on the label,” he said.

Dr. Cohen also called for a nationwide surveillance system in which the F.D.A. would working with poison control centers, local health departments and the Centers for Disease Control and Prevention. The system would include a rapid response team made up of toxicologists and other experts who could investigate reports and contact doctors and patients. A pilot program based on this idea was carried out in San Francisco in 2006 and shown to be successful, but it ended after one year because funding ran out.

Such a system, Dr. Cohen said, would help the kind of patients he has treated as  a general internist at the Cambridge Health Alliance in Massachusetts.

“I had patients who would end up hospitalized – sometimes psychiatric hospitalization, sometimes kidney failure – because they were taking these weight loss supplements that they hadn’t been telling us about,” he said. “Since then, this has been a real focus of mine. What are these lessons I’ve learned from my clinical practice telling us about the sale of supplements throughout the United States?”

While at the gym, I often overhear discussions about supplementation to get maximum muscle gain, while certainly the gym itself is stocked up on all kinds of products. But a recent Washington Post article debunks many of the beliefs regarding exercise supplements and, instead, suggests one simply eat nutritionally.

The Washington Post -

To Your Health

Just eat well — most exercise supplements are bunk

• By Stuart Gray

(By Tracy A. Woodward/The Washington Post)

I am always amazed by the wide range of sports nutrition products on sale in gyms. No matter the time of day, it seems gym-goers are always drinking nutrient shakes. The sports nutrition market has grown rapidly in the United Kingdom in the last few years. In 2012 for example, it was worth around £260m (about $437 million).

There are health benefit claims all over these products, including enhanced recovery, increased muscle mass, fat burning, better muscle definition and improved “well-being.”

With so many of these messages out there, people are obviously interested in separating the good products from the bad. As a sports scientist, I am often asked which ones people should consume when training. My general opinion is that supplements are unnecessary. You should be able to satisfy all your nutritional requirements with an appropriate diet.

But since this answer never seems to satisfy, here is a look at some of the most common supplements and the data on their importance to exercise. It is aimed at people who work out a few times a week.

Protein

The main reason for consuming protein is to increase muscle mass, because it stimulates the body to produce muscle protein. This is well established, but what is often debated is how much protein is sufficient, what type to ingest and the best time to do so.

The best type appears to be whey protein. It is absorbed into the gut more than 70 percent faster than other options, such as casein and soy protein supplements. This means it gets to the muscles more quickly, which increases the rate at which the body builds muscle protein by more than 20 percent compared to the other options.

Many gym-goers swear by something called the “anabolic window,” a claim that the protein needs to be consumed within minutes of stopping exercise for any gains to be realized. Put simply, this is pretty much hype. The window is likely 24 to 48 hours, rather than a few minutes.

As for how much protein to consume, a recent study found that in young men between 176 and 187 pounds who weight-train regularly, it took 20 grams of whey protein to achieve the best possible result – what we in the trade call “maximal stimulation.”

Any more than 20 grams appears unnecessary, in this population, anyway. It just leads to a lot of extra protein being excreted in the urine.

Creatine

Creatine has been a popular supplement for many years, though it also occurs naturally in red meat, eggs and fish. Quite a large body of scientific evidence supports its use to gain muscle mass and enhance recovery.

When creatine is taken up into the muscle, it helps to generate energy. This allows the muscle to contract and exercise to continue. This can help enhance gains in muscle mass and strength in response to weight training.

But creatine’s effects on sport performance are less convincing. It increases body water storage, which increases body mass. In sports where body weight is important, this counteracts the muscle benefits and means there are unlikely to be benefits overall.

Vitamins

It is often assumed that vitamins are good for health. That is true, but when vitamins are taken in excess the opposite can be true for both health and exercise.

In particular vitamin C and E, which act as antioxidants, have actually been shown to hamper the body’s adaptation to exercise training. Two recent studies found that people who took large amounts of the two vitamins (1000mg/day of vitamin C and 267mg/day of vitamin E) showed no improvement in aerobic fitness or exercise performance.

This level of consumption is 250 times the recommended dietary allowance for vitamin C and 80 times that for vitamin E, though well within the range of commercially available supplements.

The study produced another important finding. Two benefits of regular exercise are that human bodies become more sensitive to insulin, meaning the person is less likely to get diabetes, and they can produce more energy by creating more of the “work horse” units in cells known as mitochondria.

The people in the study who took the vitamins found that these benefits were attenuated to some extent. This suggests that these supplements may do more harm than good, certainly if you take them in large quantities.

Caffeine

People don’t consume caffeine to help adapt their bodies to training but rather for improved performance during a single bout of exercise, such as a competition.

Taking caffeine supplements will indeed prolong your endurance during exercise. Coffee lovers will be glad to know that you can get the same benefits from coffee consumption.

Energy drinks

Carbohydrate-based drinks have been around for a long time, and have long been seen as worthwhile because of the way they increase the delivery of energy to the body and provide hydration. But in recent years the evidence supporting their ability to improve acute exercise performance has been called into question.

While I am confident these drinks are useful during prolonged, intense exercise of about two hours, they are often consumed during shorter duration exercise when they are likely to have little benefit.

There has also been a lot of concern in recent years about young children consuming these drinks without exercising much and unwittingly increasing their sugar and calorie consumption. These drinks also often contain caffeine, which is not recommended for children.

Other supplements

There are several other supplements available that claim to benefit to exercisers. These include beta-alanine, fish oil, conjugated linoleic acid, L-carnitine, L-arginine, nitrate and vitamin D. Current evidence suggests there is no apparent benefit from them.

Supplement contamination

In a recent study, 10 percent of supplements tested contained banned products, such as steroids. Clearly this creates the possibility of failing a drug test if exercising competitively. More important, it is extremely worrisome to me that these substances could be in health products that can be picked up in a local supermarket.

In short, nutrition products can benefit people who work out, but there’s so much misinformation that you may well be wasting money or even undermining your body’s performance.

If the question is, “What supplements should I take to enhance my exercise training?” the simple answer is: Nothing. Exercise, have a balanced diet and enjoy it!

Stuart Gray is  a senior lecturer at the Institute of Medical Sciences at the University of Aberdeen in Scotland. A version of this post first appeared on the Web site The Conversation.

Gerber Rice Cereal, Rice Krispies, white rice, sticky rice, brown rice, rice cakes and more...we eat a lot of rice. But rice is a grain that sucks up metal from soil, particular arsenic and/or cadmium both of which are toxic contaminants. And if you think brown rice is healthier, it absorbs even more of the toxins. Good news is that if you alternate the grains you consume, the levels are low enough as to not cause acute disease. But to be safe, can we grow rice in uncontaminated soil?

The Trouble With Rice

 

By DEBORAH BLUM

April 18, 2014, 4:40 pm

 

 

Nicky Loh/ReutersAs a plant, rice is particularly prone to absorbing certain toxic metals from the soil.

For the past few years, Mary Lou Guerinot has been keeping watch over experimental fields in southeast Texas, monitoring rice plants as they suck metals and other troublesome elements from the soil. 

If the fields are flooded in the traditional paddy method, she has found, the rice handily takes up arsenic. But if the water is reduced in an effort to limit arsenic, the plant instead absorbs cadmium — also a dangerous element. 

“It’s almost either-or, day-and-night as to whether we see arsenic or cadmium in the rice,” said Dr. Guerinot, a molecular geneticist and professor of biology at Dartmouth College. 

The levels of arsenic and cadmium at the study site are not high enough to provoke alarm, she emphasized. Still, it is dawning on scientists like her that rice, one of the most widely consumed foods in the world, is also one of nature’s great scavengers of metallic compounds. 

Consumers have already become alarmed over reports of rice-borne arsenic in everything from cereal bars to baby food. Some food manufacturers have stepped up screening for arsenic in their products, and agencies such as the Food and Drug Administration now recommend that people eat a variety of grains to “minimize potential adverse health consequences from eating an excess of any one food.” 

But it’s not just arsenic and cadmium, which are present in soil both as naturally occurring elements and as industrial byproducts. Recent studies have shown that rice is custom-built to pull a number of metals from the soil, among them mercury and even tungsten. The findings have led to a new push by scientists and growers to make the grain less susceptible to metal contamination. 

The highest levels often occur in brown rice, because elements like arsenic accumulate in bran and husk, which are polished off in the processing of white rice. The Department of Agriculture estimates that on average arsenic levels are 10 times as high in rice bran as in polished rice.

Although these are mostly tiny amounts — in the part per billion range — chronic exposure to arsenic, even at very low levels, can affect health. The F.D.A. is now considering whether a safety level should be set for arsenic in rice.

“Rice is a problem because it’s such a widely consumed grain,” said Rufus Chaney, a senior research agronomist with the U.S.D.A.’s Agricultural Research Service, who is leading a investigation of metal uptake by food crops. “But it’s also a fascinating plant.” 

Like people, plants have systems for taking up and absorbing necessary nutrients. In plants, these “transporter” systems work to pull minerals such as iron, calcium, zinc and manganese from the soil.

The rice plant has a well-designed system for taking up silicon compounds, or silicate, which help strengthen the plant and give stiffness and shape to its stems. Tissues generally referred to as phloem move such water-soluble nutrients throughout the plant. 

But that delivery system also inclines the plant to vacuum up arsenic compounds, which are unfortunately similar in structure to silicate. And the traditional methods of growing rice, which often involve flooding a field, encourage formation of a soluble arsenic compound, arsenite, that is readily transported by the rice plant. 

“The issue with the rice plant is that it tends to store the arsenic in the grain, rather than in the leaves or elsewhere,” said Jody Banks, a plant biologist at Purdue University, who studies arsenic uptake in plants. “It moves there quite easily.” 

The highest concentrations of arsenic in rice-growing regions are mostly found in parts of Asia — including Bangladesh and India — where the underlying arsenic-rich bedrock contaminates groundwater used for both drinking and irrigation of rice fields. 

But arsenic at lower levels is found in all soils, including American fields. The fertile soils fanning out across the Mississippi River floodplain are up to five times as high in arsenic as other parts of Louisiana, Mississippi and Arkansas, according to studies done by the United States Geological Survey. 

It’s for that reason, as well as for water conservation, that scientists have experimented with reducing the amount of water used for rice fields. But as Dr. Guerinot has found, that makes cadmium more available to the plant instead. 

Other plants also take up cadmium, Dr. Chaney noted, usually by the channels normally used to acquire zinc from the soil. But the rice plant, curiously, absorbs nearly all of its cadmium through a manganese transport system. And this route — discovered by a determined group of Japanese researchers — brings a new set of complications.

While zinc is relatively common in soil, soluble manganese is less readily found. So cadmium has little competition in the rice plant’s transport system — meaning that it is accumulated with apparent enthusiasm. 

The association between cadmium in rice and human disease goes back decades. Most scientists cite the identification of itai-itai (ouch-ouch) disease in Japan during the 1960s as the first recognition of this problem. The name comes from the painful effects of bone fractures, one of many health problems related to cadmium exposure. 

Researchers eventually discovered that cadmium pollution from mines and other industry had spread into rice farming areas in Japan, causing the grain to be loaded with the toxic metal. A host of similar problems have occurred in China, setting off an uproar over tainted rice last year. 

Scientists say that the cadmium occurring naturally in American soil is not high enough to cause acute disease. Still, because rice is such an important food crop, scientists are searching for ways to block its metal-acquiring tendencies.

There are efforts to breed rice plants that transfer more zinc and iron into the grain, which would both increase nutritional quality and reduce toxicity. There are also programs, including the experiment in Texas, that try to breed improved rice cultivars less prone to absorb toxic minerals. 

And researchers have explored the idea of genetic engineering to make the plant’s transport systems more precise so that cadmium or arsenic is filtered out. 

Finally, they are looking into using other plants to reduce the toxic elements in the soils themselves, a process called phytoextraction. Dr. Banks, for instance, is studying a fern that deftly pulls arsenic from the soil and stores it in the fronds. 

The plant, known as a Chinese brake or ladder fern, is so talented in this regard that the Chinese have approached American scientists about the feasibility of using it to clean up contaminated soils. Of course the ferns eventually have to be incinerated or taken to a toxic disposal site.

“You definitely wouldn’t want to eat them,” said Dr. Banks.

The idea of dieting is a temporary state rather than a change in lifestyle. Yet a change in lifestyle involves learning how to eat the right foods which, for some, requires a change in diet. A Washington Post article cites a number of studies in asking the question - Is a paleo-vegetarian diet possible?

Wellness

In the News

Is a paleo vegetarian diet possible?

 

Bigstock Photo - Trail Mix. 

By Hope Warshaw, Published: April 1

 

Question: Is it possible to follow a paleo vegetarian eating plan? 

Answer: The short answer is that it’s possible. But in entertaining this eating plan, you’ve got to examine your health goals, the plan’s nutritional soundness and whether you can follow it long-term.

Let’s unpack each part of the plan and look at the research and the nutritional pluses and minuses.

Paleo diet defined
 
This diet, also called the caveman or Stone Age diet, has recently become popular, mainly through books, the Internet and social media buzz. The premise: It’s our highly processed, grain-focused food choices that are causing our rampant rate of chronic diseases. Eating like our hunter-gatherer ancestors in the Paleolithic time will help us lose weight, minimize heart disease and Type 2 diabetes and live longer.

In: Meat, fish, poultry, eggs, nuts, seeds, vegetables and fruits.

Out: Grains, dairy foods, legumes (beans and peas), processed foods and foods containing refined sugars.

Research rundown: “If you search for controlled studies on the paleo diet, meaning it was tested against another diet, you’ll find a couple of short-term studies each done with a relatively small number of people,” says Brie Turner-McGrievy, an assistant professor and registered dietitian in health promotion, education and behavior at the University of South Carolina. Like many diet studies, these show slightly more weight loss and some improvement in chronic disease indicators for the paleo plan. But a few short-term studies don’t constitute an evidence base.

In U.S. News and World Report’s 2014 ranking of Best Diets Overall (compiled with the help of top health and nutrition experts), paleo tied for last in a group of 32 diets, with this comment: “Experts took issue with the diet on every measure. Regardless of the goal — weight loss, heart health, or finding a diet that’s easy to follow — most experts concluded that it would be better for dieters to look elsewhere.” No. 1? The government-developed DASH (Dietary Approaches to Stop Hypertension) diet.

Paleo advocates recommend eating meat and avoiding all grains, saying the grains we eat today have been dramatically changed with modern agricultural techniques. One problem they cite is greater gluten content. “The notion that our ancestors ate more meat than grains is not based in fact. Our ancestors were constantly gathering grain-based foods,” says Julie Miller Jones, a professor emeritus in nutrition at St. Catherine University in St. Paul, Minn., who has studied grains extensively. Jones adds, “Though the hunt for meat was pretty constant, the kill was rare. They didn’t sit down to Tyrannosaurus steaks every day.”

As for the gluten claim, Jones points to research sampling century-old wheat showing that the amount of gluten hasn’t changed. But she acknowledges a small increase in the population of people with gluten sensitivity and celiac disease, as well as other autoimmune diseases, such as Type 1 diabetes.

 “A lot has changed in our environment. Perhaps it’s changes in our grains, the gut, use of antibiotics or countless other factors,” Jones says.

Is it wise to omit grains? “Absolutely not. We need a variety of whole grains, as well as legumes, fruits and vegetables, to get the gamut of dietary fibers for their unique effects on the heart, digestive system and insulin and glucose control.” Plus, Jones adds, grains’ and legumes’ different types of fibers and amino acids make them a perfect nutritional match.

Nutrition pitfalls: Eliminating whole grains and legumes might leave people deficient in iron and zinc and some B vitamins. Deleting dairy could make getting enough potassium a challenge. And going heavy on animal-based proteins, which take center stage in the paleo diet, could raise saturated fat and cholesterol intake.

Vegetarian diet defined
 
The spectrum of vegetarian eating runs from the most restrictive, vegan, to lacto-ovo (eating eggs and dairy-based foods but no animals). All plant-based eaters generally consume fruits, vegetables, nuts, seeds, legumes and grains.

Research rundown: Comparatively, the evidence on vegetarian eating runs long and deep, with a host of health benefits including weight control and disease prevention.

Among the largest and longest research projects are the Adventist Health Studies, conducted over the past 40 years. The largest study in the series was conducted among nearly 100,000 Seventh-day Adventists. The researchers, based at Loma Linda University in California, use periodic questionnaires to gather data about participants’ health status, disease risk factors, eating and lifestyle habits and more. Results show that Adventist vegetarians have a lower risk of overweight, insulin resistance, metabolic syndrome, prediabetes and Type 2 diabetes than non-vegetarians in this population. And the closer people abide by a vegan diet, vs. the least-restrictive lacto-ovo vegetarian plan, the healthier they are.

The Adventist Health Study and several other large observational studies have drawn a link between reduced red-meat and processed-meat consumption and lower chronic disease risk. Turner-McGrievy points out that the more people choose plant-based foods over animal-based foods, the more they can cut down on saturated fat and cholesterol. That’s a healthy move.

But it’s not just plants that keep vegetarians healthier. Studies show they also tend to practice other healthful behaviors such as not smoking, being physically active, watching less television and getting sufficient sleep. That might turn out to be true for long-term paleo followers, but we don’t have the research yet.

Nutrition pitfalls: The more food groups a vegetarian eats, the easier it will be to meet his or her nutrition needs. Nutrients to keep an eye on: vitamins B12 and D, omega-3 fats, iron and zinc.

Paleo vegetarian?
 
The only foods that overlap in the paleo and vegetarian plans are fruits, vegetables, nuts and seeds. Translated, this would be a vegan eating plan, plus eggs, minus grains and legumes. “Following this eating plan could make it difficult to get enough protein, dietary fibers, iron, zinc and B vitamins,” Turner-McGrievy says.

Research shows most people can follow a regimented eating plan for a short time. That’s not the challenge. The challenge is finding a healthful eating plan you can follow day after day and achieve your long-term health goals. At this point, it doesn’t appear that the paleo eating plan meets these objectives for most people.

Warshaw, a registered dietitian nutritionist and certified diabetes educator, is the author of numerous books published by the American Diabetes Association and the blog EatHealthyLiveWell found on her Web site, www.hopewarshaw.com.

Time for a walk in the sun: With data on more than a million people, two studies find that blood levels of vitamin D is a good indicator of overall health and that it is worthwhile to supplement with vitamin D-3. Low levels of vitamin D were associated with death from cancer or heart disease.

Low Vitamin D Levels Linked to Disease in Two Big Studies

 

By ANAHAD O'CONNOR

April 1, 2014, 6:38 pm

 

Lawrence Lool/European Pressphoto Agency 

 

 

New research has found that lower vitamin D levels were associated with illness, but didn’t show whether they were a cause.

 

People with low vitamin D levels are more likely to die from cancer and heart disease and to suffer from other illnesses, scientists reported in two large studies published on Tuesday.

The new research suggests strongly that blood levels of vitamin D are a good barometer of overall health. But it does not resolve the question of whether low levels are a cause of disease or simply an indicator of behaviors that contribute to poor health, like a sedentary lifestyle, smoking and a diet heavy in processed and unhealthful foods.

Nicknamed the sunshine nutrient, vitamin D is produced in the body when the skin is exposed to sunlight. It can be obtained from a small assortment of foods, including fish, eggs, fortified dairy products and organ meats. And blood levels of it can be lowered by smoking, obesity and inflammation.

Vitamin D helps the body absorb calcium and is an important part of the immune system. Receptors for the vitamin and related enzymes are found throughout cells and tissues of the body, suggesting it may be vital to many physiological functions, said Dr. Oscar H. Franco, a professor of preventive medicine at Erasmus Medical Center in the Netherlands and an author of one of the new studies, which appeared in the journal BMJ.

“It has effects at the genetic level, and it affects cardiovascular health and bone health,” he said. “There are different hypotheses for the factors that vitamin D regulates, from genes to inflammation. That’s the reason vitamin D seems so promising.”

The two studies were meta-analyses that included data on more than a million people. They included observational findings on the relationship between disease and blood levels of vitamin D. The researchers also reviewed evidence from randomized controlled trials — the gold standard in scientific research — that assessed whether taking vitamin D daily was beneficial.

Dr. Franco and his co-authors — a team of scientists at Harvard, Oxford and other universities — found persuasive evidence that vitamin D protects against major diseases. Adults with lower levels of the vitamin in their systems had a 35 percent increased risk of death from heart disease, 14 percent greater likelihood of death from cancer, and a greater mortality risk overall.

When the researchers looked at supplement use, they found no benefit to taking one form of the vitamin, D2. But middle-aged and older adults who took another form, vitamin D3 — which is the type found in fish and dairy products and produced in response to sunlight — had an 11 percent reduction in mortality from all causes, compared to adults who did not. In the United States and Europe, it is estimated that more than two-thirds of the population is deficient in vitamin D. In their paper, Dr. Franco and his colleagues calculated that roughly 13 percent of all deaths in the United States, and 9 percent in Europe, could be attributed to low vitamin D levels.

“We are talking about a large part of the population being affected by this,” he said. “Vitamin D could be a good route to prevent mortality from cardiovascular disease and other causes of mortality.”

In the second study, also published in BMJ, a team of researchers at Stanford and several universities in Europe presented a more nuanced view of vitamin D.

They concluded there was “suggestive evidence” that high vitamin D levels protect against diabetes, stroke, hypertension and a host of other illnesses. But they also said there was no “highly convincing” evidence that vitamin D pills affected any of the outcomes they examined.

“Based on what we found, we cannot recommend widespread supplementation,” said Evropi Theodoratou, an author of the study and research fellow at the Center for Population Health Sciences at the University of Edinburgh. The second study also looked at bone health. While Vitamin D had long been believed to help prevent osteoporosis fractures from falls, clinical trials in recent years have challenged the idea. The study also found no evidence to support that assumption. 

“Vitamin D might not be as essential as previously thought in maintaining bone mineral density,” Dr. Theodoratou and her colleagues wrote.

Dr. Theodoratou was not alone in suggesting people hold off on taking vitamin D supplements for now. Even though Dr. Franco found them to be beneficial, he said that more research was needed to show what levels are best. Instead of taking pills, people could improve their vitamin D levels with an adequate diet and 30 minutes of sunlight twice a week, he said.

“The most important factors in obtaining vitamin D are going out and doing some exercise and following a healthy diet,” he added.

And in an editorial that accompanied the studies in BMJ, Paul Welsh and Dr. Naveed Sattar of the British Heart Foundation’s Glasgow Cardiovascular Research Center pointed out that previous research “extolled the virtues of antioxidant vitamins only for major trials of vitamins E and C and beta carotene to show null, or even some harmful, effects of supplementation.”

They said vitamin D pills should not be recommended widely until clinical trials that are underway shed more light on the benefits and potential side effects.

But Duffy MacKay, a spokesman for the Council for Responsible Nutrition, a supplement industry trade group, said that vitamin D is not easily obtained through food alone, and noted that exposure to sunlight has its dangers. 

He said he agreed with Dr. Franco that more research was needed to identify “an optimal dose and duration” of vitamin D.

“But there is enough positive research currently to indicate that people should be supplementing with vitamin D for a variety of positive health outcomes,” he added.

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This post has been revised to reflect the following correction:

Correction: April 5, 2014

An earlier version of this article incorrectly listed kale as a source of vitamin D. It is not.