Omega 3s may help cut colon cancer risk

Studies in animals and a couple of small trials in people suggest that fish oil supplementation can fight inflammation and may have cancer-fighting properties, Dr. Sangmi Kim of the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, and colleagues note. But so far studies looking at the diets of larger groups of people have had equivocal results.

To investigate further, Kim and colleagues examined the relationship between polyunsaturated fatty acid intake and bowel cancer risk in 1,503 whites (including 716 colon cancer patients and 787 healthy controls) and 369 African Americans (213 with colon cancer, 156 controls).

Among whites, the researchers found, those in the top fourth based on their omega-3 consumption had half the risk of colon cancer compared to those in the bottom fourth.

When the researchers looked separately at the two main fatty acids contained in fish oil --eicosapentaenoic acids and docosahexaenoic acids -- they found risk also fell with increasing intake.

When the researchers looked at whites and blacks together, they also found a reduced risk of colon cancer with increasing omega 3 intake; separate analysis of the black study participants didn't find this relationship.

They also found that people who consumed more omega-6 fatty acids in relation to omega-3s were more likely to have colon cancer, although omega-6 intake in and of itself didn't affect risk.

In addition to fish oils, omega-3 fatty acid sources include seed oils, such as walnut oil and flax-seed oils, and leafy green vegetables. People in the US typically eat more omega-6 fatty acids than omega-3s; top sources include palm oil, soybean oil, and sunflower oil.

The researchers also found an "unexpected" association between higher omega-3 intake and colon cancer in African-Americans, but urged caution in interpreting this finding, which they say "may have been due to chance." Nevertheless, they conclude, "whether the possible benefit from this dietary modification varies by race warrants further evaluation."

Studies in animals and a couple of small trials in people suggest that fish oil supplementation can fight inflammation and may have cancer-fighting properties, Dr. Sangmi Kim of the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, and colleagues note. But so far studies looking at the diets of larger groups of people have had equivocal results.

To investigate further, Kim and colleagues examined the relationship between polyunsaturated fatty acid intake and bowel cancer risk in 1,503 whites (including 716 colon cancer patients and 787 healthy controls) and 369 African Americans (213 with colon cancer, 156 controls).

Among whites, the researchers found, those in the top fourth based on their omega-3 consumption had half the risk of colon cancer compared to those in the bottom fourth.

When the researchers looked separately at the two main fatty acids contained in fish oil --eicosapentaenoic acids and docosahexaenoic acids -- they found risk also fell with increasing intake.

When the researchers looked at whites and blacks together, they also found a reduced risk of colon cancer with increasing omega 3 intake; separate analysis of the black study participants didn't find this relationship.

They also found that people who consumed more omega-6 fatty acids in relation to omega-3s were more likely to have colon cancer, although omega-6 intake in and of itself didn't affect risk.

In addition to fish oils, omega-3 fatty acid sources include seed oils, such as walnut oil and flax-seed oils, and leafy green vegetables. People in the US typically eat more omega-6 fatty acids than omega-3s; top sources include palm oil, soybean oil, and sunflower oil.

The researchers also found an "unexpected" association between higher omega-3 intake and colon cancer in African-Americans, but urged caution in interpreting this finding, which they say "may have been due to chance." Nevertheless, they conclude, "whether the possible benefit from this dietary modification varies by race warrants further evaluation."

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Feline Parasites in Australia

Palmer CS, Robertson ID, Traub RJ et al.: Intestinal parasites of dogs and cats in Australia: The veterinarian's perspective and pet owner awareness, Vet J 183:358, 2009.

This study used survey questionnaires to evaluate the use of routine deworming for companion animals in Australia, and the degree of client education provided by the veterinarian for the client, particularly with regard to potential parasite risks to people from their pets. The investigators summarize their findings: “Very few veterinarians routinely discussed the zoonotic potential of pet parasites with clients but most recommended regular prophylactic administration of anthelmintics throughout a pet’s life. Some pet owners were unaware of the existence of zoonoses. It is possible that an overreliance on anthelmintics may have led to a certain complacency about the need to educate pet owners about the risks of zoonoses.” They concluded that routine testing to avoid overuse of broad-spectrum antiparasitic drugs is ideal, and client education about potential risks to them and their families and precautions necessary to avoid parasitism and disease is vital. [MK]

Related articles:
Palmer CS, Traub RJ, Robertson ID et al.: Determining the zoonotic significance of Giardia and Cryptosporidium in Australian dogs and cats, Vet Parasitol 154:142, 2008.

More on cat health: Winn Feline Foundation Library
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Palmer CS, Robertson ID, Traub RJ et al.: Intestinal parasites of dogs and cats in Australia: The veterinarian's perspective and pet owner awareness, Vet J 183:358, 2009.

This study used survey questionnaires to evaluate the use of routine deworming for companion animals in Australia, and the degree of client education provided by the veterinarian for the client, particularly with regard to potential parasite risks to people from their pets. The investigators summarize their findings: “Very few veterinarians routinely discussed the zoonotic potential of pet parasites with clients but most recommended regular prophylactic administration of anthelmintics throughout a pet’s life. Some pet owners were unaware of the existence of zoonoses. It is possible that an overreliance on anthelmintics may have led to a certain complacency about the need to educate pet owners about the risks of zoonoses.” They concluded that routine testing to avoid overuse of broad-spectrum antiparasitic drugs is ideal, and client education about potential risks to them and their families and precautions necessary to avoid parasitism and disease is vital. [MK]

Related articles:
Palmer CS, Traub RJ, Robertson ID et al.: Determining the zoonotic significance of Giardia and Cryptosporidium in Australian dogs and cats, Vet Parasitol 154:142, 2008.

More on cat health: Winn Feline Foundation Library
Join us on Facebook
Follow us on Twitter
Subscribe to our e-newsletter

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Antioxidant-rich spice mix shows potential for heart health

Cooking hamburgers with a polyphenol-rich spice mix may reduce the content of compounds linked to heart disease and possible cancer, says a new study.

Using a spice mix similar to that used in the East Indian spice blend, researchers from the University of California, Los Angeles report that hamburgers were subsequently found to contain significantly lower levels of lipid-peroxidation products, claimed to produce off-flavours and linked to promotion of the processes of atherogenesis and carcinogenesis.

“The ingestion of high-fat foods that contain lipid-peroxidation products can lead to increases in plasma concentrations of malondialdehyde as well as other cytotoxic and genotoxic compounds,” explained the researchers, led by David Heber from UCLA’s Center for Human Nutrition.

Important questions remain unanswered

Commenting independently on the research Victoria Taylor, senior dietician at UK charity the British Heart Foundation, told FoodNavigator: "This is a small study which seeks to identify if the addition of herbs and spices to meat can not only affect its flavouring, but also its potential impact on heart disease.

"More research is needed to confirm the results seen here and to identify whether the same findings are observed for meats other than minced beef. The practicalities of how this would need to be translated into real diets outside of the research setting is also an important question.

"However, in the mean time, adding herbs and spices to food which is already a key recommendation to help people reduce the amount of salt in their diet, may have additional benefits for heart health,” added Taylor.

Spices for health

The study taps into the promotion of the antioxidant-activity of spices. Herbs and spices often come out on top when scientists measure the antioxidant activity of common foods. A study published in the American Journal of Clinical Nutrition (Vol. 84, pp. 95-135) published in 2006 stated that cloves had the highest antioxidant content, according to the ferric reducing ability of plasma (FRAP) assay. The rest of the top five was also spices, with top-placed cloves followed by oregano leaf, ginger, cinnamon and turmeric.

Cooking hamburgers with a polyphenol-rich spice mix may reduce the content of compounds linked to heart disease and possible cancer, says a new study.

Using a spice mix similar to that used in the East Indian spice blend, researchers from the University of California, Los Angeles report that hamburgers were subsequently found to contain significantly lower levels of lipid-peroxidation products, claimed to produce off-flavours and linked to promotion of the processes of atherogenesis and carcinogenesis.

“The ingestion of high-fat foods that contain lipid-peroxidation products can lead to increases in plasma concentrations of malondialdehyde as well as other cytotoxic and genotoxic compounds,” explained the researchers, led by David Heber from UCLA’s Center for Human Nutrition.

Important questions remain unanswered

Commenting independently on the research Victoria Taylor, senior dietician at UK charity the British Heart Foundation, told FoodNavigator: "This is a small study which seeks to identify if the addition of herbs and spices to meat can not only affect its flavouring, but also its potential impact on heart disease.

"More research is needed to confirm the results seen here and to identify whether the same findings are observed for meats other than minced beef. The practicalities of how this would need to be translated into real diets outside of the research setting is also an important question.

"However, in the mean time, adding herbs and spices to food which is already a key recommendation to help people reduce the amount of salt in their diet, may have additional benefits for heart health,” added Taylor.

Spices for health

The study taps into the promotion of the antioxidant-activity of spices. Herbs and spices often come out on top when scientists measure the antioxidant activity of common foods. A study published in the American Journal of Clinical Nutrition (Vol. 84, pp. 95-135) published in 2006 stated that cloves had the highest antioxidant content, according to the ferric reducing ability of plasma (FRAP) assay. The rest of the top five was also spices, with top-placed cloves followed by oregano leaf, ginger, cinnamon and turmeric.

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Added sugar increases heart risks: study

They said people who ate more added sugar were more likely to have higher risk factors for heart disease, such as higher triglycerides and lower levels of protective high-density lipoprotein or HDL cholesterol.

"Just like eating a high-fat diet can increase your levels of triglycerides and high cholesterol, eating sugar can also affect those same lipids," Dr. Miriam Vos of Emory School of Medicine, who worked on the study published in the Journal of the American Medical Association, said in a statement.

The study adds to mounting pressure on U.S. food companies to make their foods healthier as newly passed U.S. health reform legislation shifts the nation's focus on ways to prevent, rather than simply treat disease.

A report by the influential Institute of Medicine released on Tuesday recommended that the U.S. Food and Drug Administration start to regulate sodium intake in foods.

And several states, including New York and California, have weighed a tax on sweetened soft drinks to defray the cost of treating obesity-related diseases.

The addition of sweeteners to prepared foods and beverages in recent decades has sharply increased Americans' daily intake of sugar and overall calories, according to Vos and colleagues.

But no major studies have looked at the impact of too much sugar on levels of fat in the blood.

The researchers asked 6,000 adults what they ate and then grouped them by sugar intake and cholesterol levels.

On average, nearly 16 percent of people's daily calories came from added sugar.

The highest-consuming group ate an average of 46 teaspoons of added sugar per day, while the lowest-consuming group ate an average of only about 3 teaspoons daily.

"It would be important for long-term health for people to start looking at how much added sugar they're getting and finding ways to reduce that," Vos said in a statement.

Too much sugar not only contributes to obesity, but also is a key culprit in diabetes, high blood pressure, heart disease and stroke, according to the American Heart Association.

The association warned last August that Americans need to cut back dramatically on sugar consumption, recommending that women eat no more than 100 calories per day of added processed sugar a day, or six teaspoons (25 grams), while men should keep it to just 150 calories of added processed sugar per said or nine teaspoons (37.5 grams).

Kelly Brownell of Yale University told Reuters last month a penny-per-ounce (penny-per-28 grams) tax on soft drinks could cut the consumption of sugar-sweetened drinks by the average American from 50 gallons (189 liters) annually to 38.5 gallons (146 liters).

He expects such a tax could also cut healthcare costs by about $50 billion over 10 years and raise $150 billion in revenue over the same period.

The American Beverage Association says sugar-sweetened drinks do not pose any particular health risk, and are not a unique risk factor for obesity or heart disease

They said people who ate more added sugar were more likely to have higher risk factors for heart disease, such as higher triglycerides and lower levels of protective high-density lipoprotein or HDL cholesterol.

"Just like eating a high-fat diet can increase your levels of triglycerides and high cholesterol, eating sugar can also affect those same lipids," Dr. Miriam Vos of Emory School of Medicine, who worked on the study published in the Journal of the American Medical Association, said in a statement.

The study adds to mounting pressure on U.S. food companies to make their foods healthier as newly passed U.S. health reform legislation shifts the nation's focus on ways to prevent, rather than simply treat disease.

A report by the influential Institute of Medicine released on Tuesday recommended that the U.S. Food and Drug Administration start to regulate sodium intake in foods.

And several states, including New York and California, have weighed a tax on sweetened soft drinks to defray the cost of treating obesity-related diseases.

The addition of sweeteners to prepared foods and beverages in recent decades has sharply increased Americans' daily intake of sugar and overall calories, according to Vos and colleagues.

But no major studies have looked at the impact of too much sugar on levels of fat in the blood.

The researchers asked 6,000 adults what they ate and then grouped them by sugar intake and cholesterol levels.

On average, nearly 16 percent of people's daily calories came from added sugar.

The highest-consuming group ate an average of 46 teaspoons of added sugar per day, while the lowest-consuming group ate an average of only about 3 teaspoons daily.

"It would be important for long-term health for people to start looking at how much added sugar they're getting and finding ways to reduce that," Vos said in a statement.

Too much sugar not only contributes to obesity, but also is a key culprit in diabetes, high blood pressure, heart disease and stroke, according to the American Heart Association.

The association warned last August that Americans need to cut back dramatically on sugar consumption, recommending that women eat no more than 100 calories per day of added processed sugar a day, or six teaspoons (25 grams), while men should keep it to just 150 calories of added processed sugar per said or nine teaspoons (37.5 grams).

Kelly Brownell of Yale University told Reuters last month a penny-per-ounce (penny-per-28 grams) tax on soft drinks could cut the consumption of sugar-sweetened drinks by the average American from 50 gallons (189 liters) annually to 38.5 gallons (146 liters).

He expects such a tax could also cut healthcare costs by about $50 billion over 10 years and raise $150 billion in revenue over the same period.

The American Beverage Association says sugar-sweetened drinks do not pose any particular health risk, and are not a unique risk factor for obesity or heart disease

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Berries cut lower type 2 diabetes and CVD risk, claims new research

Berries rich in polyphenols decrease the postprandial glucose response of sucrose in healthy subjects, according to a new study in the British Journal of Nutrition.

Sucrose increases postprandial blood glucose concentrations, and diets with a high glycaemic response may be associated with increased risk of obesity, type 2 diabetes and CVD.

According to the World Health Organization (WHO), approximately 150 million people have diabetes mellitus worldwide, and this number may double by the year 2025 due to population growth, ageing, unhealthy diet, obesity and sedentary lifestyle.

Berries are excellent sources of various polyphenols, such as anthocyanins, flavonols, phenolic acids, ellagitannins and proanthocyanidins, said the researchers from the University of Kuopio in Finland.

And, several in vitro and in vivo studies, said the authors, have suggested that polyphenols may influence carbohydrate digestion and absorption and thereby postprandial glycaemia.

“Polyphenols have inhibited intestinal a-glucosidase (maltase and sucrase) activity and glucose transport in vitro,” states the article.

The Finnish researchers hold that reduced rates of sucrose digestion and/or absorption from the gastrointestinal tract are the most probable mechanisms underlying the delayed and attenuated glycaemic response from consumption of polyphenols.

They said that in previous human studies, beverages rich in polyphenolic compounds have shown beneficial effects on postprandial glycaemia: “Delayed absorption of glucose after consumption of apple juice and coffee and attenuated glycaemic response to sucrose consumed in chlorogenic acid-enriched coffee have been reported.”

Method

In the present study, the Finnish researchers said they investigated the glycaemic effect of a berry puree made of bilberries, blackcurrants, cranberries and strawberries, and sweetened with sucrose, in reference to sucrose alone.

And they said that they used a control meal to achieve the similar profile and amounts of available carbohydrates, which included 250 ml water, 35 g sucrose, 4.5 g glucose and 5.1 g fructose.
A total of 12 healthy subjects (eleven women and one man, aged 25–69 years) with normal fasting plasma glucose ingested 150 g of the berry purée with 35 g sucrose or a control sucrose load in a randomised, controlled cross-over design, added the team.

The researchers said the subjects were screened by blood tests and a structured interview on previous and current diseases, current medication, alcohol and tobacco consumption, physical activity and use of nutrient supplements.

Each subject was studied in two three hour meal tests, on separate days, at least five days apart, they explained.

The authors said that the test meals were administered in a randomised order in an open-label design, with the participants advised to keep their medication, lifestyles and body weight constant and to follow their habitual diet throughout the study.

In the evening before the test, the subjects were instructed to avoid berries, and to consume a meal of choice and repeat that meal before the second test.

Berries rich in polyphenols decrease the postprandial glucose response of sucrose in healthy subjects, according to a new study in the British Journal of Nutrition.

Sucrose increases postprandial blood glucose concentrations, and diets with a high glycaemic response may be associated with increased risk of obesity, type 2 diabetes and CVD.

According to the World Health Organization (WHO), approximately 150 million people have diabetes mellitus worldwide, and this number may double by the year 2025 due to population growth, ageing, unhealthy diet, obesity and sedentary lifestyle.

Berries are excellent sources of various polyphenols, such as anthocyanins, flavonols, phenolic acids, ellagitannins and proanthocyanidins, said the researchers from the University of Kuopio in Finland.

And, several in vitro and in vivo studies, said the authors, have suggested that polyphenols may influence carbohydrate digestion and absorption and thereby postprandial glycaemia.

“Polyphenols have inhibited intestinal a-glucosidase (maltase and sucrase) activity and glucose transport in vitro,” states the article.

The Finnish researchers hold that reduced rates of sucrose digestion and/or absorption from the gastrointestinal tract are the most probable mechanisms underlying the delayed and attenuated glycaemic response from consumption of polyphenols.

They said that in previous human studies, beverages rich in polyphenolic compounds have shown beneficial effects on postprandial glycaemia: “Delayed absorption of glucose after consumption of apple juice and coffee and attenuated glycaemic response to sucrose consumed in chlorogenic acid-enriched coffee have been reported.”

Method

In the present study, the Finnish researchers said they investigated the glycaemic effect of a berry puree made of bilberries, blackcurrants, cranberries and strawberries, and sweetened with sucrose, in reference to sucrose alone.

And they said that they used a control meal to achieve the similar profile and amounts of available carbohydrates, which included 250 ml water, 35 g sucrose, 4.5 g glucose and 5.1 g fructose.
A total of 12 healthy subjects (eleven women and one man, aged 25–69 years) with normal fasting plasma glucose ingested 150 g of the berry purée with 35 g sucrose or a control sucrose load in a randomised, controlled cross-over design, added the team.

The researchers said the subjects were screened by blood tests and a structured interview on previous and current diseases, current medication, alcohol and tobacco consumption, physical activity and use of nutrient supplements.

Each subject was studied in two three hour meal tests, on separate days, at least five days apart, they explained.

The authors said that the test meals were administered in a randomised order in an open-label design, with the participants advised to keep their medication, lifestyles and body weight constant and to follow their habitual diet throughout the study.

In the evening before the test, the subjects were instructed to avoid berries, and to consume a meal of choice and repeat that meal before the second test.

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Effect of Catnip on Shelter Cats

Ellis SLH, Wells DL: The influence of olfactory stimulation on the behaviour of cats housed in a rescue shelter, Applied Animal Behaviour Science 123:56, 2010.

This study looked at the impact of environment enrichment in a shelter situation through provision of “novel smells” (odors other than those normally encountered in the shelter environment) in the cat’s enclosure. The odor exposure in the form of odorless cloth, or cloths with odor of rabbit, catnip, or lavender, were placed in the pen with the cat for three hours daily on five consecutive days (30 cats per “odor”, and one group of 30 with no cloth). The cats’ behavior was recorded every five minutes on days 1, 3, and 5. Overall, cats showed relatively little interest in the cloths, spending just over 6% of the total observation time interacting with these stimuli. However, animals exposed to the catnip-impregnated cloths exhibited significantly more interest in the stimulus than animals exposed to the other cloths, spending an average of 11% of the observation time interacting with the objects. Regardless of the odor, or lack thereof, the novelty of the cloth lasted only about one hour. Overall, the results suggest that certain odors, notably catnip, may hold potential as environmental enrichment for captive domestic cats. [MK]

Related articles:
Ellis SLH: Environmental enrichment: Practical strategies for improving feline welfare, J Feline Med Surg 11:901, 2009.

More on cat health:
Winn Feline Foundation Library
Join us on Facebook
Follow us on Twitter
Subscribe to our e-newsletter

Ellis SLH, Wells DL: The influence of olfactory stimulation on the behaviour of cats housed in a rescue shelter, Applied Animal Behaviour Science 123:56, 2010.

This study looked at the impact of environment enrichment in a shelter situation through provision of “novel smells” (odors other than those normally encountered in the shelter environment) in the cat’s enclosure. The odor exposure in the form of odorless cloth, or cloths with odor of rabbit, catnip, or lavender, were placed in the pen with the cat for three hours daily on five consecutive days (30 cats per “odor”, and one group of 30 with no cloth). The cats’ behavior was recorded every five minutes on days 1, 3, and 5. Overall, cats showed relatively little interest in the cloths, spending just over 6% of the total observation time interacting with these stimuli. However, animals exposed to the catnip-impregnated cloths exhibited significantly more interest in the stimulus than animals exposed to the other cloths, spending an average of 11% of the observation time interacting with the objects. Regardless of the odor, or lack thereof, the novelty of the cloth lasted only about one hour. Overall, the results suggest that certain odors, notably catnip, may hold potential as environmental enrichment for captive domestic cats. [MK]

Related articles:
Ellis SLH: Environmental enrichment: Practical strategies for improving feline welfare, J Feline Med Surg 11:901, 2009.

More on cat health:
Winn Feline Foundation Library
Join us on Facebook
Follow us on Twitter
Subscribe to our e-newsletter

Read More

Low Vitamin D Levels Associated With More Asthma Symptoms and Medication Use

ScienceDaily (Apr. 15, 2010) — Low levels of vitamin D are associated with lower lung function and greater medication use in children with asthma, according to researchers at National Jewish Health. In a paper published online this week in the Journal of Allergy & Clinical Immunology, Daniel Searing, MD, and his colleagues also reported that vitamin D enhances the activity of corticosteroids, the most effective controller medication for asthma.

"Asthmatic children in our study who had low levels of vitamin D were more allergic, had poorer lung function and used more medications," said Dr. Searing. "Conversely, our findings suggest that vitamin D supplementation may help reverse steroid resistance in asthmatic children and reduce the effective dose of steroids needed for our patients."

The researchers examined electronic medical records of 100 pediatric asthma patients referred to National Jewish Health. Overall, 47 percent of them had vitamin D levels considered insufficient, below 30 nanograms per milliliter of blood (ng/mL). Seventeen percent of the patients had levels below 20 ng/mL, which is considered deficient. These levels were similar to vitamin D levels found in the general population.

Patients low in vitamin D generally had higher levels of IgE, a marker of allergy, and responded positively to more allergens in a skin prick test. Allergies to the specific indoor allergens, dog and house dust mite, were higher in patients with low vitamin D levels. Low vitamin D also correlated with low FEV1, the amount of air a person can exhale in one second, and lower FEV1/FVC, another measure of lung function. Use of inhaled steroids, oral steroids and long-acting beta agonists were all higher in patients low in vitamin D.

"Our findings suggest two possible explanations," said senior author Donald Leung, MD, PhD. "It could be that lower vitamin D levels contribute to increasing asthma severity, which requires more corticosteroid therapy. Or, it may be that vitamin D directly affects steroid activity, and that low levels of vitamin D make the steroids less effective, thus requiring more medication for the same effect."

The researchers performed a series of laboratory experiments that indicated vitamin D enhances the action of corticosteroids. They cultured some immune cells with the corticosteroid dexamethasone alone and others with vitamin D first, then dexamethasone. The vitamin D significantly increased the effectiveness of dexamethasone. In one experiment vitamin D and dexamethasone together were more effective than 10 times as much dexamethasone alone.

The researchers also incubated immune-system cells for 72 hours with a staphylococcal toxin to induce corticosteroid resistance. Vitamin D restored the activity of dexamethasone.

"Our work suggests that vitamin D enhances the anti-inflammatory function of corticosteroids,' said Dr. Leung. "If future studies confirm these findings vitamin D may help asthma patients achieve better control of their respiratory symptoms with less medication."

This study comes on the heels of another paper by National Jewish Health faculty, which showed that low levels of vitamin D in adult asthma patients are associated with lower lung function and reduced responsiveness to corticosteroids.

ScienceDaily (Apr. 15, 2010) — Low levels of vitamin D are associated with lower lung function and greater medication use in children with asthma, according to researchers at National Jewish Health. In a paper published online this week in the Journal of Allergy & Clinical Immunology, Daniel Searing, MD, and his colleagues also reported that vitamin D enhances the activity of corticosteroids, the most effective controller medication for asthma.

"Asthmatic children in our study who had low levels of vitamin D were more allergic, had poorer lung function and used more medications," said Dr. Searing. "Conversely, our findings suggest that vitamin D supplementation may help reverse steroid resistance in asthmatic children and reduce the effective dose of steroids needed for our patients."

The researchers examined electronic medical records of 100 pediatric asthma patients referred to National Jewish Health. Overall, 47 percent of them had vitamin D levels considered insufficient, below 30 nanograms per milliliter of blood (ng/mL). Seventeen percent of the patients had levels below 20 ng/mL, which is considered deficient. These levels were similar to vitamin D levels found in the general population.

Patients low in vitamin D generally had higher levels of IgE, a marker of allergy, and responded positively to more allergens in a skin prick test. Allergies to the specific indoor allergens, dog and house dust mite, were higher in patients with low vitamin D levels. Low vitamin D also correlated with low FEV1, the amount of air a person can exhale in one second, and lower FEV1/FVC, another measure of lung function. Use of inhaled steroids, oral steroids and long-acting beta agonists were all higher in patients low in vitamin D.

"Our findings suggest two possible explanations," said senior author Donald Leung, MD, PhD. "It could be that lower vitamin D levels contribute to increasing asthma severity, which requires more corticosteroid therapy. Or, it may be that vitamin D directly affects steroid activity, and that low levels of vitamin D make the steroids less effective, thus requiring more medication for the same effect."

The researchers performed a series of laboratory experiments that indicated vitamin D enhances the action of corticosteroids. They cultured some immune cells with the corticosteroid dexamethasone alone and others with vitamin D first, then dexamethasone. The vitamin D significantly increased the effectiveness of dexamethasone. In one experiment vitamin D and dexamethasone together were more effective than 10 times as much dexamethasone alone.

The researchers also incubated immune-system cells for 72 hours with a staphylococcal toxin to induce corticosteroid resistance. Vitamin D restored the activity of dexamethasone.

"Our work suggests that vitamin D enhances the anti-inflammatory function of corticosteroids,' said Dr. Leung. "If future studies confirm these findings vitamin D may help asthma patients achieve better control of their respiratory symptoms with less medication."

This study comes on the heels of another paper by National Jewish Health faculty, which showed that low levels of vitamin D in adult asthma patients are associated with lower lung function and reduced responsiveness to corticosteroids.

Read More