NUTRITION REVIEW

Omega-3 Fatty Acids May Support the Health of Bipolar Individuals

Ethyl-eicosapentaenoic acid (EPA), the omega-3 fatty acid derived from fish, reduced depression in subjects with bipolar disorder when given in conjunction with standard bipolar treatment, a new study has found.

Epidemiological and clinical studies suggest that increased intake of eicosapentaenoic acid (EPA) alleviates unipolar depression. Consequently, a group of researchers from London sought to examine whether EPA could help with depression in bipolar disorder.

In the 12-week, randomized, double-blind, placebo-controlled study, 75 patients with bipolar disorder were randomized into one of three groups. One group of 26 patients received a placebo, another group of 24 subjects received 1 gram per day of ethyl-EPA, and a third group of 25 subjects received 2 grams per day of ethyl-EPA. The researchers then noted any changes in the Hamilton Rating Scale for Depression (HRSD) in order to assess outcome. The researchers also assessed changes in the Young Mania Rating Scale and Clinical Global Impression Scale (CGI).

After treatment with ethyl-EPA, the subjects’ scores on the Hamilton Rating Scale for Depression and Clinical Global Impression Scale significantly improved compared to subjects taking a placebo. One gram per day of ethyl-EPA was as effective as two grams per day. Both doses were well tolerated.

The study authors concluded, “Adjunctive ethyl-EPA is an effective and well-tolerated intervention in bipolar depression.”

Reference:
Frangou S, Lewis M, McCrone P. Efficacy of ethyl-eicosapentaenoic acid in bipolar depression: randomised double-blind placebo-controlled study. Br J Psychiatry. 2006 Jan;188:46-50.

Benfotiamine Alleviates Oxidative Stress in Brains of Diabetic Rodents

Benfotiamine, a derivative of thiamine, reduces the free radical caused oxidative damage that occurs in the brains of diabetic mice, a new study shows.

Diabetes often results in a deficiency of the B vitamin thiamine along with multiple organ damage including diabetic neuropathy. Consequently, researchers in the current study decided to investigate whether the thiamine derivative benfotiamine would improve the health of diabetic mice.

Male mice were made diabetic by the injection of a substance called streptozotocin. Control and diabetic mice received benfotiamine (100 mg/kg per day administered within the lining of the abdominal cavity) for 14 days. The researchers then evaluated oxidative stress and protein damage in the animals. Pro-oxidative or pro-inflammatory factors including advanced glycation end-products (AGEs) and tissue factor and tumor necrosis factor-alpha (TNF-alpha) were also evaluated. AGEs are toxic end products that occur when there are ongoing, high levels of sugars and hormones in the body. TNF-alpha is a protein produced by white blood cells that helps regulate the immune response.

Four weeks after diabetes was induced in the animals, the mice suffered from hyperglycemia, enhanced cerebral oxidative stress and elevated TNF-alpha and AGE levels. In the diabetic animals treated with benfotiamine, however, the diabetes-induced cerebral oxidative stress was significantly reduced without affecting levels of AGEs or TNF-alpha.

The researchers concluded that the results indicated benfotiamine may reduce diabetes-induced cerebral oxidative stress through a mechanism unrelated to stopping the formation of AGEs and TNF-alpha.

Reference:
Wu S, Ren J. Benfotiamine alleviates diabetes-induced cerebral oxidative damage independent of advanced glycation end-product, tissue factor and TNF-alpha. Neurosci Lett. 2006 Feb 13;394(2):158-62. Epub 2005 Oct 28.


Green Tea Intake Linked to Improved Brain Health
One of the first studies to investigate the link between green tea and brain health in humans has found that green tea consumption is linked to a reduced prevalence of cognitive impairment.

Past cell culture and animal studies have found that green tea may protect the brain against degenerative processes leading to Alzheimer’s and Parkinson’s and that it can inhibit the buildup of amyloid proteins associated with Alzheimer’s. However, until now, human studies have not been done.

In the current study, researchers analyzed data from 1,003 Japanese subjects who had participated in a community-based Comprehensive Geriatric Assessment conducted in 2002. The subjects, aged 70 or older, completed a self-administered questionnaire that included questions about their diets, overall physical health, lifestyle habits and frequency of green tea consumption. Researchers evaluated cognitive function by using the Mini-Mental State Examination, which measures memory, attention and language use.

The results indicated that higher green tea consumption was associated with a lower prevalence of cognitive impairment. Subjects who consumed two or more cups of green tea per day had about half the chance of developing cognitive impairment compared to those who drank three cups or less each week. Participants who drank about one cup per day also reduced their risk of mental decline, although not by as much as those consuming two or more cups per day.

Green tea’s protective effect on cognitive function remained even after the researchers adjusted for overall diet, smoking and exercise habits.

The study authors suggest that green tea’s potential ability to support brain health may help explain the lower rate of Alzheimer’s disease in Japan compared with Europe and North America.

Reference:
Kuriyama S, Hozawa A, Ohmori K, Shimazu T, Matsui T, Ebihara S, Awata S, Nagatomi R, Arai H, Tsuji I. Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project 1. Am J Clin Nutr. 2006 Feb;83(2):355-61.

Leptin Levels Linked to Asthma
Adults, especially women, who have high levels of the hormone leptin, have a higher incidence of asthma, a new study has found.

In the past, adipose (fat) tissue was thought to serve no purpose. Research has begun to unveil, however, that fat cells are constantly producing pro-inflammatory and anti-inflammatory cytokines (proteins important in immunity). High levels of leptin, one of these pro-inflammatory cytokines produced by fat cells, has previously been shown to be associated with asthma in children. Consequently, the researchers of the current study hypothesized that leptin concentrations, by virtue of pro-inflammatory actions, also may be associated with asthma in adults.

Researchers analyzed subjects who had participated in The Third National Health and Nutrition Examination Survey. Information about fasting serum leptin concentrations and a self-report of doctor-diagnosed asthma were gathered from the study participants.

Among 5,876 participants, subjects with current asthma had a higher mean unadjusted leptin concentration than those who never had asthma. The mean leptin concentration was 11.1 micrograms per liter for those who had never had asthma and 13.7 for those who currently had asthma, a statistically significant difference.

The association between leptin and asthma appeared stronger among women than men, and among premenopausal women than postmenopausal women. Body mass index (BMI) also was associated with current asthma in women. However, when the researchers adjusted for leptin concentrations, the link between leptin and asthma appeared to be independent of obesity.

The study authors theorize that leptin’s role in the body may go beyond that of promoting obesity and that one of its main effects is that of promoting inflammation. Since asthma is an inflammatory disease, this new role for leptin would explain the development of this condition.

Reference:
Sood A, Camargo Jr CA, Ford ES. Association between leptin and asthma in adults. Thorax. 2006 Mar 15; [Epub ahead of print].

Cinnamon Lowers Blood Sugar in Diabetic Animals
Cinnamon lowers blood sugar and raises levels of HDL, the “good” cholesterol, in type 2 diabetic rats, a new study has found.

Researchers administered cinnamon extract at different dosages (50, 100, 150 and 200 mg/kg) to the animals for 6 weeks. At the end of the study, blood glucose concentration was significantly decreased in a dose-dependent manner with the largest reduction in the 200 mg/kg group compared with the control. HDL-cholesterol levels were significantly higher and the concentration of triglycerides and total cholesterol were significantly lower after the 6-week study.

“These results suggest that cinnamon extract has a regulatory role in blood glucose level and lipids,” the study authors wrote, “and it may also exert a blood glucose-suppressing effect by improving insulin sensitivity or slowing absorption of carbohydrates in the small intestine.”

Reference:
Kim SH, Hyun SH, Choung SY. Anti-diabetic effect of cinnamon extract on blood glucose in db/db mice. J Ethnopharmacol. 2006 Mar 8;104(1-2):119-23. Epub 2005 Oct 5.

Vitamin D Supports Immunity, Prevents Falls in the Elderly
Two new studies have unearthed important findings about vitamin D3’s role in health. One study indicates vitamin D3 has antimicrobial actions that can protect against such bacterial infections as tuberculosis, while the other study finds that together with calcium it can limit the number of falls in the elderly.

In the one study, published in the journal Science, vitamin D3 triggered a key antimicrobial response in humans against Mycobacterium tuberculosis (TB).

In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria. The researchers in the current study have discovered that when TLR activates human macrophages, the expression of the vitamin D receptor is upregulated within these immune cells. Also upregulated in the immune cells was a gene that activates the enzyme that converts vitamin D to its active form. When vitamin D’s active form was added to the immune cells, this triggered the action of an antimicrobial peptide that helps kill intracellular TB. However, when the vitamin D receptor and vitamin D activating enzyme were inhibited, the antimicrobial peptide remained dormant.

In addition, the researchers observed that blood serum from African-American individuals, known to have increased susceptibility to tuberculosis, had low vitamin D levels. The serum from the African Americans was less efficient in triggering the antimicrobial peptide that kills TB. However, when researchers added vitamin D to serum samples from African-American subjects, it restored the antibacterial properties of the peptide that kills TB.

Based on these results, the study authors believe that “differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection.”

The findings also may help explain why African-Americans, who are often deficient in vitamin D, are more susceptible to TB.

The other study indicates vitamin D, when combined with calcium, may reduce the risk of falling in elderly women by 65 percent.

Although a recent meta-analysis found that vitamin D could reduce falls by more than 20 percent, little is known about whether supplemental vitamin D plus calcium citrate malate will lower the long-term risk of falling in elderly individuals. Vitamin D and calcium may be able to prevent falls because when the elderly fall, it is not the fall that breaks their hips but rather the hip snaps, resulting in a fall. The researchers decided to see whether the bone-strengthening effects of these two supplements could reduce the rate of falls.

Researchers studied the effect of 3 years’ supplementation with vitamin D3 and calcium on the risk of falling at least once in 199 men and 246 women 65 years or older who were living at home. Individuals received 700 IU of vitamin D3 plus 500 mg of calcium citrate malate per day or a placebo in a randomized, double-blind manner. Subjects were classified as less physically active if physical activity was below the median level.

In 3 years, 55 percent of women and 45 percent of men reported at least 1 fall. Vitamin D3-calcium significantly reduced the odds of falling in ambulatory older women by 46 percent. In less active women, vitamin D3 and calcium reduced falls by 65 percent. No reduction in risk occurred in men.

References:
Liu PT, Stenger S, Li H, Wenzel L, Tan BH, Krutzik S, Ochoa MT, Schauber J, et al. Toll-Like Receptor Triggering of a Vitamin D-Mediated Human Antimicrobial Response. Science. Published Online February 23, 2006. DOI: 10.1126/science.1123933

Bischoff-Ferrari HA, Orav EJ, Dawson-Hughes B. Effect of cholecalciferol plus calcium on falling in ambulatory older men and women: a 3-year randomized controlled trial. Arch Intern Med. 2006 Feb 27;166(4):424-30.