Inability of Liver to Produce DHA May Contribute to Alzheimer’s

UC Irvine researchers have discovered that markedly depleted amounts of an omega 3 fatty acid in brain tissue samples from Alzheimer’s patients may be due to the liver’s inability to produce the complex fat, also contained in fish-oil supplements.

Low levels of docosahexaenoic acid, or DHA, have been associated with the chronic neurodegenerative disease affecting millions of Americans, but no cause had been identified.

In postmortem liver tissue from Alzheimer’s patients, the UCI team found a defect in the organ’s ability to make DHA from shorter molecules present in leafy plants and other foods. Previous studies have shown that most brain DHA is manufactured in the liver.

Non-Alzheimer’s livers did not have this defect, said Daniele Piomelli, the Louise Turner Arnold Chair in the Neurosciences and director of the Center for Drug Discovery at UCI, who led the research with Giuseppe Astarita, project scientist in pharmacology.

“We all know Alzheimer’s is a brain disease, but our findings—which were totally unexpected—show that a problem with liver fat metabolism can make people more vulnerable,” Piomelli said. “They also suggest a reason why clinical trials in which Alzheimer’s patients are given omega-3 fatty acids to improve cognitive skills have had mixed results.”

The study appears Sept. 8 in the open-access, peer-reviewed journal PLoS ONE.

DHA occurs naturally in cold-water fatty fish and seaweed. It is essential for the proper functioning of adult human brains and for the development of our nervous system and vision during the first six months of life. Omega 3 fatty acids are also part of a healthy diet that helps lower risk of heart disease.

“Additionally, we found that the greater the amount of Alzheimer’s-related cognitive problems experienced in life by the patients, the lower were their liver DHA levels,” Astarita said. “So we do see a connection.”

Piomelli added that the results point to new diagnostic and dietary approaches to Alzheimer’s: Specific blood lipid profile tests might identify at-risk persons, and dietary supplements with a chemically enhanced form of DHA may benefit early-stage patients.

“Our research isn’t advocating that liver metabolism is a key to Alzheimer’s,” he noted. “The factors causing the disease are many and complex, but we feel this is another piece in the Alzheimer’s puzzle.”

O Abençoado Alho

O alho (Allium sativum) é um vegetal da família Liliacerae, sendo encontrado na forma de raiz. Seu bulbo, vulgarmente conhecido como cabeça, é constituído por vários dentes, os quais são empregados como condimento culinário e como medicamento há centenas de anos em todo o mundo. Este emprego na culinária o coloca em vantagem frente a outras ervas de efeito farmacológico conhecido e desejável como o Ginkgo biloba, por exemplo.
Antigamente, no Egito, o alho era usado para remediar a diarréia e, na Grécia antiga, ele era empregado como medicamento no tratamento de patologias pulmonares e intestinais. Pesquisas recentes identificaram que o alho possui ainda diversas propriedades dentre as quais se destacam as antimicrobianas, antineoplásicas, terapêuticas contra doenças cardiovasculares, imunoestimulatórias e hipoglicemiante.
Pasteur relatou, em 1858, a atividade antibacteriana do alho que tem sido confirmada por diversos autores até hoje. Em laboratório, mediante diluição em série, o extrato fresco de alho mostrou ser capaz de inibir o crescimento de 14 espécies de bactérias, entre as quais o Stafilococcus aureus, Klebsiella peneumoniae e Escherichia coli, que são bactérias potencialmente maléficas à saúde. Isto ainda se deu, mesmo usando o extrato de alho diluído 128 vezes.
Uma solução de 5% preparada com alho fresco desidratado mostrou atividade bactericida contra Salmonella typhimurium. Isto é atribuído à alicina, o componente chave da atividade antimicrobiana que também é responsável pelo odor característico do alho. A atividade antimicrobiana do alho é reduzida com sua fervura pois a alicina é desnaturada durante o processamento térmico.
O alho ainda tem se mostrado ser capaz de combater o Helicobacter pylory, a maior causa de dispepsia, câncer gástrico e também de úlceras gástricas e duodenais. Foi observado recentemente que 2g/L de extrato de alho inibe completamente o crescimento do H. pylori. Os autores concluíram que este efeito bactericida pode contribuir para prevenir a formação de câncer gástrico.
Esta evidência foi comprovada num estudo epidemiológico efetuado na China, onde foi notado que: O risco de câncer gástrico é 13 vezes menor em indivíduos que consomem 20g/dia de alho em relação aqueles que consomem menos que 1g/dia. Em outro estudo, na Itália, foi observada uma correlação negativa entre o consumo de alho e o risco de câncer gástrico (risco relativo = 0,8). O efeito anticancerígeno do alho parece estar ligado à estimulação da enzima hepática glutationa S-transferase envolvida em processos de detoxicação de muitos carcinógenos.
A seguir, no quadro 1, podemos observar a composição centesimal do alho.
O que mais se destaca na composição nutricional do alho, são os altos teores dos elementos zinco e selênio, ambos metais antioxidantes. No organismo humano, estes nutrientes estão envolvidos tanto direta como indiretamente no funcionamento do sistema imunológico.
Diversos são os estudos que têm identificado baixos níveis sangüíneos tanto de selênio como de zinco, em pacientes portadores de patologias como a AIDS, onde o sistema imunológico encontra-se gravemente debilitado. A prescrição dietoterápica atualmente feita para tais pacientes preconiza o consumo de alho, entre outras coisas. Há estudos que apontam para uma atividade anti-viral do alho. Neste sentido, seu consumo também é indicado para casos de resfriado, gripe e nas viroses em geral.
A propriedade imunoestimulatória do alho está, também, relacionada à presença de substâncias encontradas no seu extrato (dialil trisulfito e dialil sulfito) que estimulam a imudidade de uma maneira geral (estimula a proliferação de células T e de citocinas produzidas por macrófagos). Neste sentido, estudos têm demonstrado que o alho atua estimulando tanto a imunidade humoral como a celular.
Outro efeito nutracêutico notável do alho esta relacionado aos benefícios cardiovasculares que ele proporciona. O consumo regular de alho reduz o nível do colesterol sérico total, evita a agregação plaquetária e também possui atividade antioxidante, prevenindo aterosclerose e doenças cardiovasculares. Estudo canadense efetuado com homens moderadamente hipercolesterolêmicos (32 a 68 anos) mostrou que o consumo de 7,2g/dia de extrato de alho durante meio ano reduz em 5,5% a pressão arterial sistólica, em 7,0% o colesterol sérico total e em 4,6% o colesterol de baixa densidade (LDL).
A atividade hipocolesterolêmica do alho se deve à inibição de diversos passos enzimáticos da síntese hepática do colesterol e a um acréscimo na excreção de ácido biliar e de esteróis. Os componentes do alho alicina, alinina e S-alil sulfato exibem propriedades que inibem a agregação plaquetária. O efeito em rede de tais propriedades resulta na prevenção da aterosclerose e das doenças cardiovasculares.
Na prevenção de doenças, o alho também tem merecido destaque. Recentemente, um estudo epidemiológico efetuado em duas regiões distintas da China, uma que emprega o alho na culinária e outra que não o utiliza, mostrou que a região que usa regularmente o alho tem menores índices de morbidade e de mortalidade em relação a região que não utiliza o alho na alimentação.
Se não bastasse todos os benefícios à saúde aqui descritos, o alho ainda possui propriedades hipoglicemiantes. O extrato de alho mediante seu componente sulfóxido S-alilciteína, reduziu significantemente a glicose sangüínea. O mecanismo provável desta atuação se deve, ao menos em parte, ao estímulo à secreção de insulina pelas células ß do pâncreas.



Quadro 1 - Pricipais benefícios do consumo regular de alho na
quantidade mínima de 8g/dia.
Aumenta a longevidade
Reduz os riscos de infarto
Favorece o bom funcionamento do sistema imunológico
Reduz a glicose sanguínea
Reduz o colesterol LDL (ruim)
Aumenta o colesterol HDL (bom)
Combate bactérias e vírus
Previne a aterosclerose
Previne o câncer
Melhora a qualidade de vida
Em resumo, os dados dos estudos apontam para diversos benefícios à saúde derivados do consumo regular do alho. Isto torna o alho uma especiaria extremamente atrativa de ser incluída no cardápio diário não somente pelo seu aroma e sabor, mas também pelos seus benefícios medicinais.

GOED Publishes Review of DHA, Alzheimer’s Study

In the Nov. 3, 2010 issue of the Journal of the American Medical Association (JAMA), researchers reported that the rate of cognitive and functional decline in patients with mild to moderate Alzheimer's disease was not slowed by supplementing with DHA, the most abundant long-chain omega 3 fatty acid in the brain.

The Global Organization for EPA and DHA Omega-3s (GOED), Salt Lake City, UT, has published a Rapid Review analyzing the JAMA study in its Advances in EPA and DHA Research journal. The complete review can be found here.

"While this trial examined DHA's impact on patients who already had Alzheimer’s disease, it's important to keep in mind that most experts emphasize omega 3's benefits likely lie in the prevention or delayed onset of many health conditions, including dementia and Alzheimer's,” said Harry Rice, PhD, vice president of regulatory and scientific affairs, GOED. “Two prior studies, MIDAS and OmegAD, were randomized, double-blind, placebo-controlled trials that showed a benefit to individuals with age-related cognitive decline or very mild Alzheimer's disease, respectively.

Cranberry: Prostate Health

Source: Br J Nutr, August 31, 2010:1-9. [Epub ahead of print]

Research: Lower urinary tract symptoms (LUTS) are a common condition in older men. The objective of this study was to evaluate the efficacy and tolerability of cranberry (Vaccinium macrocarpon) powder in men at risk of prostate disease with LUTS, elevated prostate-specific antigen (PSA), negative prostate biopsy and clinically confirmed chronic non-bacterial prostatitis. Forty-two participants received either 1500 mg of the dried powdered cranberries per day for 6 months (21 subjects) or no cranberry treatment (21 subjects). Physical examination, International Prostate Symptom Score, quality of life (QoL), five-item version of the International Index of Erectile Function (IIEF-5), basic clinical chemistry parameters, haematology, Se, testosterone, PSA (free and total), C-reactive protein (CRP), antioxidant status, transrectal ultrasound prostate volume, urinary flow rate, ultrasound-estimated post-void residual urine volume at baseline, and at 3 and 6 months, and urine ex vivo anti-adherence activity were determined in all subjects.

Results: In contrast to the control group, patients in the cranberry group had statistically significant improvement in International Prostate Symptom Score, QoL, urination parameters, including voiding parameters (rate of urine flow, average flow, total volume and post-void residual urine volume) and lower total PSA level on day 180 of the study. There was no influence on blood testosterone or serum CRP levels. The results of the present trial, researchers believe, are the first firm evidence that cranberries may ameliorate LUTS, independent of benign prostatic hyperplasia or C-reactive protein level.

Eating Habits Vary by Generation

U.S. adults, across all generations, understand the principles of healthy eating. While the majority of adults recognize the need to eat healthy, their translation into healthy eating behavior varies by generation, according to a new report by market researcher NPD Group.

The report found that older generations eat more healthfully than younger generations, but four out of five adults (nearly 170 million people) still have a diet that needs improvement.

Titled, “Healthy Eating Strategies by Generation,” the report identifies the gaps between actual consumption behaviors and intentions. It also found that younger generations—Generation X, Y and younger Boomers, ages 21 to 54—have the least healthful diets. Older consumers, ages 54 and up, often have the greatest need to eat healthy due to underlying medical conditions, and are driven to do so.

What the generations appear to have in common, the report found, is a shared understanding of what constitutes healthy eating. Adult consumers, across generations, define healthy eating consistently and are aware of the top characteristics of healthy eating and of a healthy lifestyle: exercise regularly, eat well balanced meals, eat all things in moderation, limit/avoid foods with saturated fat or cholesterol or trans fats, and drink at least eight glasses of water per day.

"Educating consumers about proper health and nutrition need not be the primary goal for food manufacturers," said Dori Hickey, director of product development at NPD and author of the report. "Connecting the dots for consumers in terms of a product benefit to a fundamental characteristic of healthy eating is more the challenge."

The nutritional value of foods is also front-and-center with many adults, according to the report, which draws on NPD's continual tracking of actual consumption behavior over the past three decades. Almost 85 million adults ranked nutritional value/healthful as #1 or #2 in importance as a need driver in deciding what to eat and drink; taste and price/value are in the top three for the three younger generations. For older consumers, freshness replaces price/value in ranked importance.

While many aspects of their diets could use improvement, overall, the largest deficiencies in adults' diets are insufficient intake of fruits, vegetables and dairy products and over consumption of total fats. Consumption of total fats is the most critical for those 54 and older.

"It comes down to adult consumers needing help to improve the healthfulness of their diets," said Hickey. "Knowing which consumer groups need the most help and understanding how to address consumers' current and future needs and desires for healthy food is the opportunity for food and beverage marketers."

Omega 3s-EPA, DHA, ALA

Dietary sources of omega-3 fatty acids include fish oil and certain plant/nut oils. Fish oil contains both docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), while some nuts (English walnuts) and vegetable oils (canola, soybean, flaxseed/linseed, olive) contain alpha-linolenic acid (ALA).

There is evidence from multiple studies supporting intake of recommended amounts of DHA and EPA in the form of dietary fish or fish oil supplements lowers triglycerides, reduces the risk of death, heart attack, dangerous abnormal heart rhythms, and strokes in people with known cardiovascular disease, slows the buildup of atherosclerotic plaques ("hardening of the arteries"), and lowers blood pressure slightly. However, high doses may have harmful effects, such as an increased risk of bleeding. Although similar benefits are proposed for alpha-linolenic acid, scientific evidence is less compelling, and beneficial effects may be less pronounced.

Some species of fish carry a higher risk of environmental contamination, such as with methylmercury.

Cranberry

There is some human evidence supporting the use of cranberry juice and cranberry supplements to prevent urinary tract infection (UTI), although most available studies are of poor quality. There are no clear dosing guidelines, but given the safety of cranberry, it may be reasonable to recommend the use of moderate amounts of cranberry juice cocktail to prevent UTI in non-chronically ill individuals.

Cranberry has not been shown effective as a treatment for documented UTI. Although cranberry may be used as an adjunct therapy in some cases, given the proven efficacy of antibiotics, cranberry should not be considered a first line treatment.

Cranberry has been investigated for numerous other medicinal uses, and promising areas of investigation include prevention of H. pylori infection, which causes gastrointestinal ulcers and dental plaque.