Health for life

Treating infection-prone patients over a 12-month period with high doses of vitamin D reduces their risk of developing respiratory tract infection – and consequently their antibiotic requirement. This according to a new study by researchers at Karolinska Institutet and Karolinska University Hospital published in the online scientific journal BMJ Open.

"Our research can have important implications for patients with recurrent infections or a compromised immune defence, such as a lack of antibodies, and can also help to prevent the emerging resistance to antibiotics that come from overuse," says Peter Bergman, researcher at Karolinska Institutets Department of Laboratory Medicine and doctor at Karolinska University Hospitals Immunodeficiency Unit. "On the other hand, there doesnt seem to be anything to support the idea that vitamin D would help otherwise healthy people with normal, temporary respiratory tract infections."

Vitamin D is synthesised in the skin through exposure to sunlight and obtained through certain foods. In Sweden there is a seasonal variation in vitamin D in the blood, the trough coming during the darker half of the year. Studies have shown that low levels of vitamin D can increase the risk of infection, and it has long been known that the vitamin can also activate the immune defence.

For the present study now published in BMJ Open the researchers examined whether treatment with vitamin D can prevent and relieve respiratory tract infections in particularly infection-prone patients. All the 140 participants from the Immunodeficiency Unit had symptoms of disease in their respiratory tracts for at least 42 days prior to the study. The patients were randomly divided into two groups, one of which received vitamin D in relatively high doses, the other a placebo. They were also asked to keep a diary recording their state of health every day during the year-long study period.

The results show that symptoms of respiratory tract infection declined by almost a quarter and the use of antibiotics by almost half. Vitamin D treatment was also tolerated well by all patients and gave no serious side-effects.

The effect of vitamin D on respiratory tract infection is controversial, and a major study from New Zeeland published recently in the scientific journal JAMA found that it did not reduce the incidence or severity of viral respiratory tract infections. However, the present study differs from the JAMA study in several important respects, which could explain their different results. The JAMA study examined a group of healthy people with initially normal levels of vitamin D in the blood, and used bolus dose administration (i.e. large doses on fewer occasions), which is thought to be less effective that daily doses.

"However, the most important difference is probably due to the fact that our participants had much lower initial levels of vitamin D than those in the New Zealand study," says Dr Anna-Carin Norlin, doctoral student and co-lead author of the study along with Dr Bergman. "There is evidence from previous studies that vitamin D supplements are only effective in patients who fall well below the recommended level, which also suggests that it would be wise to check the vitamin D levels of patients with recurrent infections."

Publication: Vitamin D3 supplementation in patients with frequent respiratory tract infections - a randomized and double blind intervention study, Bergman P*, Norlin AC*, Hansen S, Rekha RS, Agerberth B, Björkhem-Bergman L, Ekström L, Lindh JD, Andersson J (*equal contribution), BMJ Open, online 13 December 2012.

Cranberries are more than a holiday favorite, given their remarkable nutritional and health benefits. A new research review published in the international journal Advances in Nutrition provides reasons why these tiny berries can be front and center and not just a side dish. The review authors conclude that cranberries provide unique bioactive compounds that may help reduce the incidence of certain infections, improve heart health and temper inflammation.

Ten worldwide experts in cranberry and health research contributed to the article, including scientists and medical experts from Tufts University, Pennsylvania State University, Boston University, Rutgers University, French National Institute for Agricultural Research, University of East Anglia in the United Kingdom and Heinrich-Heine-University in Germany. The authors included more than 150 published research studies to create the most thorough and up-to-date review of the cranberry nutrition and human health research.

"Hundreds of studies show that the bioactive compounds found in cranberries improve health," said lead author Jeffrey Blumberg, PhD, FASN, FACN, CNS, Director of the Antioxidants Research Laboratory and Professor in the Friedman School of Nutrition Science and Policy at Tufts University. "For example, the polyphenols found in cranberries have been shown to promote a healthy urinary tract and exert protective benefits for cardiovascular disease and other chronic conditions."

Based on the totality of the published cranberry research, the authors concluded that the cranberry fruit is truly special because of the A-type proanthocyanidins (a polyphenol from the flavanol family), in contrast to the B-type proanthocyanidins present in most other types of berries and fruit. The A-type proanthocyanidins appear to provide the anti-adhesion benefits that help protect against urinary tract infections (UTI), which affect more than 15 million U.S. women each year. They present evidence suggesting that cranberries may also reduce the recurrence of UTIs – an important approach for relying less on antibiotic treatment for the condition.

Cranberry Health Benefits Extend Beyond Urinary Tract Health

The authors also cite data that shows the cranberry may improve cardiovascular health by improving blood cholesterol levels and lowering blood pressure, inflammation and oxidative stress. Cranberries have been shown to help support endothelial function and reduce arterial stiffness. Together, these benefits may promote overall health and functioning of blood vessels to help slow the progression of atherogenesis and plaque formation, which can lead to heart attacks and stroke.

Need Fruit? Eat More Cranberries

While all fruit contributes necessary vitamins and minerals to the diet, berry fruits offer a particularly rich source of health-promoting polyphenols. Because of their tart taste and very low natural sugar content, sugar is often added to cranberry products for palatability. Even with added sugar, cranberry products typically have a comparable amount of sugar to other unsweetened fruit juices and dried fruit products. Additionally, the 2010 Dietary Guidelines for Americans asserts that the best use of calories from added sweeteners is for improving the palatability of nutrient-rich foods, as is the case when adding sugar to cranberries. As an additional option, non-nutritive sweeteners are used to produce low calorie versions of cranberry products. Americans can help increase their fruit intake by incorporating cranberries and cranberry products into their diet and there is no need to wait for the holidays – cranberries can be enjoyed year round – fresh, frozen, dried, or in a juice or sauce.