Pleasant Stone Farm Clinical Reports

A few cups of hibiscus tea a day may reduce blood pressure and offer cardiovascular benefits for people at risk of developing hypertension, says a new study from Tufts University.

Three 240 mL servings a day of tea made with hibiscus (Hibiscus sabdariffa L.) were associated with a 7.2 mmHg reduction in systolic blood pressure and a 3.1 mmHg reduction in diastolic blood pressure, compared to 1.3 and 0.5 mmHg in the placebo group, according to findings published in The Journal of Nutrition.

Researchers from the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University report that this is the first placebo-controlled clinical trial to study if hibiscus tea, in an amount easily attained from the diet, may affect blood pressure.

“Hypertension is a major risk factor for cardiovascular disease and is associated with substantial morbidity and mortality, estimated to account for 35 per cent of myocardial infarction and stroke, 49 per cent of heart failure, and 24 per cent of premature mortality,” wrote the researchers, led by Dr Diane McKay.

“The dietary change assessed in this study, i.e. regularly incorporating 3 servings/d of hibiscus tea into the diet, effectively reduces blood pressure in pre- and mildly-hypertensive adults.

“This strategy may be useful in preventing the progression to moderate or more severe hypertension, potentially reducing the subsequent risk of developing cardiovascular disease,” they added.

Study details

Dr McKay and her co-workers recruited 65 adult with pre- and mild hypertension, and aged between 30 and 70, to participate in their randomised, double-blind, placebo-controlled clinical trial.

Subjects were randomly assigned to consume either three servings of brewed hibiscus tea per day or a placebo drink for six weeks. At the end of the study people in the hibiscus tea group displayed an average reduction of 7.2 mmHg in their systolic blood pressure, compared to 1.3 mmHg in the placebo group. A slight but not significant decrease in diastolic blood pressure was also recorded in the hibiscus tea group.

The benefits of hibiscus tea appeared to be greater in people who had higher systolic blood pressure at the start of the study.

Commenting on the potential mechanism, Dr McKay and her co-workers note that previous studies indicated that hibiscus may act by relaxing blood vessels, and this may be linked to calcium channels, or inhibition of the angiotensin converting enzyme (ACE), thereby preventing the conversion of angiotensin I to the potent vasoconstrictor, angiotensin II.

There is also evidence in the scientific literature that hibiscus may act as a diuretic. Another possible explanantion for the apparent benefits is related to the anthocyanin content of H. sabdariffa.

“The specific attributes of H. sabdariffa to cardiovascular health, including its ability to lower BP and its potential hypocholesterolemic effects, are not well understood and further research in this area is warranted,” added the researchers.

Source: Journal of Nutrition
February 2010, Volume 140, Issue 2, Pages 298-303
“Hibiscus sabdariffa L. tea (tisane) lowers blood pressure in pre-hypertensive and mildly hypertensive adults”
Authors: D.L. McKay, C.Y. Chen, E. Saltzman, J.B. Blumberg

Oxygenated carotenoids, lutein and zeaxanthin, supplied from the diet benefit eye health, according to a new study published in the Institute of Food Technologists’ Journal of Food Science.

Carotenoids, a group of pigments found mainly in green leafy vegetables and colored fruits, are deposited selectively in different tissues. Lutein and zeaxanthin, found in kale and spinach, are deposited in the retina while lycopene, for example, found richly in tomatoes, is concentrated in the prostate.

Scientists have long suspected a link between lutein and zeaxanthin and improved eye function. In 1866, Schulze suggested that the yellow pigments of the macula led to improvements in human vision. These pigments were later found to be derived from dietary lutein and zeaxanthin.

Visual performance

In 1933, Walls and Judd suggested that these yellow intraocular pigments could improve visual performance by absorbing light scattered both within, by minimizing glare, and outside of the eye. This resulted, they suggested, from increasing visual range by absorbing blue light scattered in the atmosphere and by improving spatial vision through enhancing contrast and reducing chromatic blur.

The latest study concluded that: “It seems clear that MP (macular pigment) does influence visual performance through, at least, a few optical mechanisms. The most robust effects appear to be related to its actions as an optical filter.”

Macular pigment is thought to improve glare performance through absorption of forward scattered short-wave (blue) light. And there’s preliminary data to suggest that it increases visual range by absorbing short-wave scattered light in the atmosphere, according to the researchers.

The pigment also appears to enhance contrast by improving the visibility of colored edges through differential absorption across a color border.

Retina and lens

Lutein and zeaxanthin could also improve vision through biological means. There’s much evidence to suggest that the pigments protect the retina and lens (Hammond and Renzi) and prevent age-related eye diseases such as macular degeneration (Carpentier and others 2009) and cataracts.

But the ability of lutein and zeaxanthin to filter light depends on individual differences in the dietary intake of these carotenoids, said the researchers. One study (Curran-Celentano et al 2001) specifically linked low average levels of macular protein (a peak OD of 0.21) with low average intakes of lutein and zeaxanthin of about 1.1 mg/d – or the equivalent of several tablespoons of spinach.

So, argue the researchers, if amounts of macular pigment in the eye vary so significantly, any function these pigments might serve would vary equally significantly.

And it is likely that a healthier retina and lens, particularly in the elderly, is related to improved visual performance.

Source: Journal of Food Science

Title: The Influence of Dietary Lutein and Zeaxanthin on Visual Performance

Authors: J. Stringham, E. Bovier, J. Wong and B. Hammond.

Increased blood levels of vitamin D may reduce the risk of colorectal cancer by as much as 40 per cent, says a study with people from 10 European countries.

The study, published in the British Medical Journal, is said to be the largest of its kind to date and adds to the science supporting the apparent health benefits from increased vitamin D. Indeed, a meta-analysis published in the American Journal of Preventive Medicine in 2007 reported that higher blood levels of vitamin D were associated with a lower risk of colon cancer.

The link between vitamin D intake and protection from cancer dates from the 1940s when Frank Apperly demonstrated a link between latitude and deaths from cancer, and suggested that sunlight gave “a relative cancer immunity”.

“However, before any public health recommendations can be made for vitamin D supplementation, new randomised trials are needed to test the hypothesis that increases in circulating 25-(OH)D concentration are effective in reducing colorectal cancer risk without inducing serious adverse events,” wrote the researchers behind the new study, from six European countries.

Study details

Using data from over half a million participants of the European Prospective Investigation into Cancer Study (EPIC), the researchers analysed dietary and lifestyle information obtained from questionnaires, and collected blood samples.

During the course of the study, 1,248 cases of colorectal cancer were diagnosed and matched with 1,248 healthy controls.

Colorectal cancer accounts for nine per cent of new cancer cases every year worldwide. The highest incidence rates are in the developed world, while Asia and Africa have the lowest incidence rates.

It remains one of the most curable cancers if diagnosis is made early.

The EPIC data showed that blood levels of vitamin D below a mid-level of 50 to 75 nanomoles per litre were associated with an increased risk of colorectal cancer, while blood levels above this were not associated with any additional benefits, said the researchers.

The association was significantly stronger for colon cancer than rectal cancer, added the researchers.

“Additionally, higher consumption of dietary calcium, but not dietary vitamin D, was found to be associated with a reduced risk of colorectal cancer,” they report.

Plausible mechanism(s)?

Commenting on the potential protective action of vitamin D with respect to colorectal carcinogenesis, the EPIC scientists noted that both vitamin and mineral may be involved. “The main proposed colorectal cancer protective mechanisms of calcium action (binding bile acids and fatty acids) could pertain largely to its concentration in the colorectal milieu rather than to a direct vitamin D-mediated effect,” they said.

Controversy

The potential benefits for the vitamin, alone or in combination with calcium, for colorectal health are somewhat controversial, with some studies reporting benefits while others report null results.

Indeed, back in 2006 results from the Women’s Health Initiative (WHI) stated that daily supplements of vitamin D and calcium ‘had no effect’ on the risk of colorectal cancer. The results were questioned however and independent cancer experts said at the time that the claims should be interpreted in the light of the complexities of the study.

Michele Forman and Bernard Levin from the MD Anderson Cancer Center at the University of Texas, noted that the WHI trial had three overlapping components, with 69 per cent of the women enrolled on the Dietary Modification trial, 54 per cent enrolled on the Hormone Therapy trial, and 14 per cent enrolled on both.

“The enrolment in three overlapping trials maximised the participation and size of the WHI trial but created a complex approach with potential confounders for biological interpretation,” said Forman and Levin.

Source: British Medical Journal
2010; 340: b5500, doi:10.1136/bmj.b5500
“Association between pre-diagnostic circulating vitamin D concentration and risk of colorectal cancer in European populations:a nested case-control study”
Authors: M. Jenab, H.B. Bueno-de-Mesquita, P. Ferrari, F.J.B. van Duijnhoven, et al.

The medicinal herb milk thistle can reduce liver inflammation caused by chemotherapy in cancer patients, according to a new study published in the online edition of Cancer, the American Cancer Society journal.

The researchers randomly assigned 50 children undergoing chemotherapy for acute lymphoblastic leukemia which caused liver inflammation a milk thistle treatment or a placebo.

After 56 days of oral treatment with milk thistle in capsule form, patients who received the treatment showed significantly lower levels of aspartate aminotransferase (AST) and trends toward lower alanine aminotransferase (ALT) and bilirubin compared with those who received the placebo.

Endure higher doses

Also, milk thistle treatment seemed to help patients to endure higher doses of chemotherapy. Sixty-one percent of the children receiving milk thistle needed dose reductions compared with 72 percent of the children receiving placebo. But the difference was not significant, noted the researchers.

Their report concluded that the study: “…provides preliminary evidence that milk thistle may be a safe, effective, supportive-care agent.”

In a statement issued by the American Cancer Society, lead researcher Dr Kara Kelly, New York-Presbyterian Hospital/Columbia University Medical Center’s Herbert Irving Comprehensive Cancer Center, commented: “Milk thistle needs to be studied further, to see how effective it is for a longer course of treatment, and whether it works well in reducing liver inflammation in other types of cancers and with other types of chemotherapy. However, our results are promising as there are no substitute medications for treating liver toxicity.”

Chemotherapy drugs often cause liver inflammation requiring lower than optimal doses or a temporary suspension of treatment until the inflammation subsides which can compromise its effectiveness.

Appropriate dose

Further research is needed to determine the appropriate dose and duration of milk thistle therapy and its ability to prevent chemotherapy induced liver inflammation, according to the researchers.

Milk thistles are flowering plants of the daisy family (Asteraceae ). Native to the Mediterranean Europe, the seeds of milk thistle have been used for 2000 years to treat chronic liver disease and protect the liver against toxins.

The name milk thistle derives from the plants’ mottled leaves which contain a milky sap.

Extracts are available from drugstores, herbal medicine shops and internet vendors.

The study was funded by the American Institute for Cancer Research, the Tamarind Foundation and the National Cancer Institute.

Drugs used in the study were donated by Thorn Research, which produces the milk thistle extract.

Primary source: Cancer American Cancer Society journal
Title: A randomized, controlled, double-blind, pilot study of milk thistle for the treatment of hepatotoxicity in childhood acute lymphoblastic leukemia (ALL)

Increased intakes of vitamin E may reduce the risk of bladder cancer by about 35 per cent, says a new study from an international team of researchers

Findings published in Cancer Causes and Control also showed that carotenoids, niacin, thiamine, and vitamin D may reduce the risk of bladder cancer in older people.

“The effects of vitamin E, carotenoids, vitamin D, thiamin, and niacin in relation to the risk of developing bladder cancer may warrant further investigation,” report the researchers, led by Maree Brinkman from The Cancer Council Victoria in Australia.

“Future studies should focus on optimal doses and combinations of these micronutrients particularly for high risk groups such as heavy smokers and older individuals,” they state.

Bladder cancer is diagnosed in about 336,000 people every year worldwide, and it is three times more likely to affect men than women, according to the European School of Oncology.

Study details

Brinkman and her co-workers analysed dietary data from 322 people with bladder cancer and 239 healthy controls. A 121-item food frequency questionnaire was used to estimate dietary intakes.

Results showed that, in general, people with the highest average intakes of vitamin E (at least 193.4 milligrams per day) were 34 per cent less likely to develop bladder cancer. The highest average intakes of phosphorous (1,557 milligrams) were associated with a 51 per cent reduction in bladder cancer risk.

“Although we observed an approximate 50 per cent reduction in the odds of bladder cancer associated with higher dietary intake of phosphorus, it was not statistically significant,” wrote the researchers. “Given this ubiquitous micronutrient is an important physiological component of DNA, RNA, ATP, and cell membranes, it may be worthy of further consideration.”

When the researchers focused their analysis on smokers, they found that the highest intakes of vitamin E, carotenoids (18 milligrams), and niacin (46.5 milligrams), were associated with a 42, 38, and 34 per cent reduction in bladder cancer risk in heavy smokers.

In older individuals, the highest average intakes of carotenoids, vitamin D (641 International Units), thiamin (3.35 milligrams), niacin, and vitamin E were all associated with a reduced bladder cancer risk.

“Bladder cancer is a disease that typically affects older people, and bioavailability of B-group vitamins may be compromised in this demographic by certain drugs (e.g., acid lowering agents),” stated the researchers. “Additionally, vitamin E, like carotenoids acts as an antioxidant and, as suggested by our results, could be more beneficial under conditions of the greatest oxidative stress such as smoking and ageing.”

The researchers called for additional study to further examine these potentially protective relationships.

The study was supported by the National Institute of Environmental Health Sciences and the National Cancer Institute at the US National Institutes of Health (NIH).

Source: Cancer Causes and Control
Published online ahead of print, doi: 10.1007/s10552-009-9490-0
“Minerals and vitamins and the risk of bladder cancer: results from the New Hampshire Study”
Authors: M.T. Brinkman, M.R. Karagas, M.S. Zens, A. Schned, R.C. Reulen, M.P. Zeegers

A metabolite of ellagic acid found in pomegranates may inhibit an enzyme called aromatase that converts androgen to oestrogen, and that also plays a key role in the development of breast cancer, according to findings published in Cancer Prevention Research.

Researchers from the City of Hope in Duarte, California and the University of California, Los Angeles said they were surprised by their findings. “We previously found other fruits, such as grapes, to be capable of the inhibition of aromatase. But, phytochemicals in pomegranates and in grapes are different,” said principal investigator Shiuan Chen, PhD.

Pomegranate, a rich source of antioxidants, has been linked to improved heart health, but a growing body of science indicates the fruit protect against prostate cancer. Studies have also reported a role in joint health by slowing cartilage loss in arthritis.

It is these antioxidants, and particularly ellagitannin compounds like punicalagins and punicalins, which accounts for about half of the fruit’s antioxidant ability, that are reportedly behind the proposed health benefits.

Note of caution

Commenting independently on the findings, Professor Gary Stoner from Ohio State University said additional studies will be needed to confirm these initial findings.

“This is an in vitro study in which relatively high levels of ellagitannin compounds were required to demonstrate an anti-proliferative effect on cultured breast cancer cells,” said Stoner. “It’s not clear that these levels could be achieved in animals or in humans because the ellagitannins are not well absorbed into blood when provided in the diet.”

Study details

Chen and his co-workers screened 10 ellagitannin-derived compounds from pomegranates, including ellagic acid, gallagic acid, and urolithins A and B against a breast cancer cell line. According to the researchers, ellagitannin are converted to ellagic acid in the body, and this is then converted to urolithins by gut microflora.

The results showed that urolithin B was the most potent inhibitor of breast cancer cell growth at doses of 2.35 and 4.7 micromoles per litre in the in-cell assay.

“The ingestion of pomegranate juice can lead to concentrations of circulating urolithins reaching up to 18 micromoles per litre in blood,” said the researchers. “Taken together with the results of current studies and reports of the presence of urolithin A and urolithin B in the blood and urine of human subjects following pomegranate ingestion, the results of these analyses suggest that pomegranate intake may be a viable strategy for the chemoprevention of breast cancer.”

Intriguing

Powel Brown from University of Texas M. D. Anderson Cancer Center echoed Stoner’s sentiments and called the results “intriguing”.

“More research on the individual components and the combination of chemicals is needed to understand the potential risks and benefits of using pomegranate juice or isolated compounds for a health benefit or for cancer prevention,” said Brown. “This study does suggest that studies of the ellagitannins from pomegranates should be continued.”

Until then, Stoner said people “might consider consuming more pomegranates to protect against cancer development in the breast and perhaps in other tissues and organs”.

The study was supported by the National Institutes of Health.

Source: Cancer Prevention Research
Published online ahead of print, doi: 10.1158/1940-6207.CAPR-08-0225
“Pomegranate Ellagitannin–Derived Compounds ExhibitAntiproliferative and Antiaromatase Activity in Breast Cancer Cells In vitro”
Authors: L.S. Adams, Y. Zhang, N.P. Seeram, D. Heber, S. Chen

Low blood levels of vitamin D have again been linked to lower survival in the elderly – a study which strengthens calls to confirm if vitamin D supplements could offer protection.

Writing in the journal Clinical Endocrinology, scientists from the Netherlands, Austria, and the US report that low blood levels of the sunshine vitamin are associated with increased risk of all-cause mortality, and mortality from heart disease.

“Our results provide a rationale for future studies to test whether vitamin D supplementation reduces mortality and/or cardiovascular diseases in persons with vitamin D deficiency,” wrote the researchers, led by Stefan Pilz from the Medical University of Graz in Austria

“These studies are urgently needed to answer the question whether vitamin D deficiency is a cause or a consequence of a poor health status,” they added.

Snowballing science

The research follows hot on the heels of similar findings published in Nutrition Research by scientists led by Richard Semba from the Johns Hopkins University. The researchers looked at vitamin D levels in the form of 25- hydroxyvitamin D (25(OH)D), , in 714 community-dwelling women, aged between 70 and 79 years, participating in the Women’s Health and Aging Studies I and II.

Semba and his co-workers noted that several biologic mechanisms could explain a causal relationship between vitamin D deficiency and mortality, with the vitamin’s active form (1,25-dihydroxyvitamin D) linked to a range of effects including control of inflammatory compounds, regulating immune health and blood pressure, or reducing arterial hardening.

Prior to this, a study published in the Archives of Internal Medicine grabbed headlines around the world when it reported that . This earlier study used data from 13,331 men and women participating in the Third National Health and Nutritional Examination Survey (NHANES III).

New data

The new study used data from 614 people participating in the Hoorn Study, a prospective population-based study with men and women with an average age of 69.8. Blood levels of 25(OH)D were measured at the start of the study.

After an average of six years of follow-up, 51 deaths had been documented, 20 of which were due to cardiovascular health.

People with the lowest average vitamin D levels (30.6 nanomoles per litre) were found to be at a 124 and 378 per cent increased risk of all-cause mortality and cardiovascular mortality, respectively.

Commenting on the potential mechanism, the researchers note: “Apart from the maintenance of muscular and skeletal health, vitamin D may also protect against cancer, infections, autoimmune and vascular diseases, suggesting that vitamin D deficiency might contribute to a reduced life expectancy.”

D details

Vitamin D refers to two biologically inactive precursors – D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive.

While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.

In adults, it is said vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 diabetes.

Source: Clinical Endocrinology
November 2009, Volume 71, Issue 5, Pages: 666-672
“Vitamin D and mortality in older men and women”
Authors: S. Pilz, H. Dobnig, G. Nijpels, R.J. Heine, C.D.A. Stehouwer, M.B. Snijder, R.M. van Dam, J.M. Dekker

Supplementation with soy-germ derived isoflavones may reduce the loss of bone in postmenopausal women, according to results of a new study from the US.

However, the isoflavones did not slow bone loss at common fracture sites, according to results published in the American Journal of Clinical Nutrition.

Over 400 postmenopausal women participated in the multicenter, randomised, double-blind, placebo-controlled two year, which used either 80 or 120 mg of soy hypocotyl aglycone isoflavones (Frutarum’s SoyLife) plus calcium (400 mg) and vitamin D (400 IU).

Only the 120 mg per day produced benefits, with significantly reduced loss of whole body bone mineral density (BMD) after both one and two years.

“The attenuated whole body bone mineral density in healthy postmenopausal women for 2 y probably translates to minimal clinical benefits; yet the long-term significance, particularly with regard to fracture prevention, remains to be determined,” wrote the researchers, led by William Wong from the USDA/ARS Children’s Nutrition Research Center at the Baylor College of Medicine in Texas.

“The benefit of soy isoflavone supplementation at 120 mg/d in reducing the loss of whole body BMD, however, was not reflected in bone mineral content values among the regional sites or among the serum biochemical markers of bone metabolism,” they added.

With the World Health Organisation calling osteoporosis its biggest global healthcare problem, limiting bone loss in post-menopausal women could ease the burden of osteoporosis. According to the International Osteoporosis Foundation, the total direct cost of osteoporotic fractures is €31.7 bn in Europe.

Previous studies have reported conflicting results concerning soy isoflavones (40 to 99 mg/d doses) and bone health for postmenopausal women.

Study details

Wong and his co-workers recruited 403 postmenopausal women aged between 40 and 60 were recruited to participate in the study. Smokers and women already suffering from osteoporosis were not allowed to participate.

The women were randomly assigned to receive daily supplementation of soy hypocotyl aglycone isoflavones (80 or 120 mg) or placebo for two years. All the women were given calcium and vitamin D supplements.

After two years, the researchers recorded statistically significant smaller reduction in whole body BMD in the women receiving the 120 mg soy isoflavones, compared to the placebo group.

However, when compared with the placebo, soy isoflavone supplementation had no effect on changes in regional BMD, bone mineral content, or other biochemical markers of bone metabolism, said the researchers.

“It is possible that lifetime intake of soy is needed to see a significant protective association on bone mass conservation,” wrote the researchers.

The study was funded by the USDA and by the National Institutes of Health (NIH).

Previous data

A meta-analysis published in the European Journal of Clinical Nutrition (doi: 10.1038/sj.ejcn.1602748) concluded doses of soy isoflavones less than 90 mg per day may improve bone density.

Previous studies from China have linked soy isoflavones to increases in bone mineral density (BMD), while a recent large study in the Archives of Internal Medicine (2005, Vol. 165, pp. 1890-1895) reported that high soy consumption was linked with a 48 per cent decrease in fractures for women who had been menopausal for less than 10 years.

Source: American Journal of Clinical Nutrition
November 2009, Vol. 90, No. 5, 1433-1439, doi:10.3945/ajcn.2009.28001
“Soy isoflavone supplementation and bone mineral density in menopausal women: a 2-y multicenter clinical trial”
Authors: W.W. Wong, R.D. Lewis, F.M. Steinberg, M.J. Murray, M.A. Cramer, P. Amato, R.L. Young, S. Barnes, K.J. Ellis, R.J. Shypailo, J.K. Fraley, K.L. Konzelmann, J.G. Fischer, E. O’Brian Smith

Increased intakes of omega-3 fatty acids may reduce the risk of developing age-related blindness by 30 per cent, says a new study from the US National Eye Institute.

A subsection of the Age-Related Eye Disease Study (AREDS) supported the beneficial effects of omega-3 consumption for preventing age-related macular degeneration, the leading cause of blindness in the over 50s.

“If these results are generalizable, they may guide the development of low-cost and easily implemented preventive interventions for progression to advanced age-related macular degeneration,” wrote the researchers, led by John Paul SanGiovanni.

Eyes on AMD

AMD is a degenerative retinal disease that causes central vision loss and leaves only peripheral vision. It is the leading cause of legal blindness for people over 55 years of age in the Western world, according to AMD Alliance International.

Despite the fact that approximately 25 to 30 million people worldwide are affected by AMD, awareness of the condition is low, says the Alliance. And as the generation of Baby Boomers gets older, the Alliance expects incidence to be on the rise and triple by 2025.

There are two types of AMD – wet and dry. The former occurs when blood vessels grow abnormally beneath the macular (neovascular AMD). The blood vessels eventually leaks and the macular is scarred, obscuring vision. Dry AMD occurs when normal tissue in the macula slowly disappears. This results in a pale area of the macular called central geographic atrophy.

Increased intakes of omega-3 fatty acids may reduce the risk of both wet and dry AMD by 35 and 32 per cent, respectively, according to findings published online in the American Journal of Clinical Nutrition.

Building omega-3’s eye benefits

It is known that omega-3 fatty acids, and particularly DHA, play an important role in the layer of nerve cells in the retina, and studies have already reported that omega-3 may protect against the onset of AMD.

Indeed, a meta-analysis published in the June 2008 issue of the Archives of Ophthalmology found that a high intake of omega-3 fatty acids and fish may reduce the risk of AMD by up to 38 per cent. Scientists from the University of Melbourne in Australia reported that the benefits were most pronounced against late (more advanced) AMD, while eating fish twice a week was associated with a reduced risk of both early and late AMD.

The new study supports these earlier findings. SanGiovanni and his co-workers looked at a sub-section of 1,837 people participating in the phase 3 Age-Related Eye Disease Study (AREDS). All the participants were considered to be at a moderate-to-high risk of advanced AMD.

Over 12 years of study, the researchers found that intakes of omega-3, estimated using a food-frequency questionnaire, were related to both wet and dry AMD risk.

Indeed, participants with the highest omega-3 intakes, equivalent to about 0.11 per cent of their total energy intakes, had a 30 per cent lower risk of developing both types than people with the lowest intakes.

“The 12-year incidence of central geographic atrophy and neovascular AMD in participants at moderate-to-high-risk of these outcomes was lowest for those reporting the highest consumption of omega-3 fatty acids,” concluded the researchers.

Being an observational study, the researchers did not consider the mechanism. However, an earlier mouse study partly funded by the National Eye Institute noted lower levels of inflammatory molecules, such as prostaglandin E2 and leukotriene B4, and higher levels of anti-inflammatory molecules, such as prostaglandin D2 (American Journal of Pathology, Vol. 175, pp.799-807).

Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.2009.27594
“Omega-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: a prospective cohort study from the Age-Related Eye Disease Study”
Authors: J.P. SanGiovanni, E. Agron, A.D. Meleth, G.F. Reed, R.D. Sperduto, T.E. Clemons, E.Y. Chew

Vitamin D may inhibit the build-up of cholesterol in blood vessels, says a new study that support calls for vitamin D supplements to improve heart health of diabetics.

According to new findings published in Circulation, diabetics – a population group at higher risk of heart disease – with low vitamin D levels displayed difficulties in processing cholesterol, putting them at an increased risk of heart attack and stroke.

“Vitamin D inhibits the uptake of cholesterol by cells called macrophages,” explained lead researcher Carlos Bernal-Mizrachi, MD. “When people are deficient in vitamin D, the macrophage cells eat more cholesterol, and they can’t get rid of it. The macrophages get clogged with cholesterol and become what scientists call foam cells, which are one of the earliest markers of atherosclerosis.”

Macrophage activation is higher in people with disease such as diabetes, and when found in combination with low vitamin D levels, the macrophages become loaded with cholesterol and eventually stiffen blood vessels and block blood flow.

“Cholesterol is transported through the blood attached to lipoproteins such as LDL, the ‘bad’ cholesterol,” he said. “As it is stimulated by oxygen radicals in the vessel wall, LDL becomes oxidated, and macrophages eat it uncontrollably. LDL cholesterol then clogs the macrophages, and that’s how atherosclerosis begins.”

And the problem may be solved by simply ensuring adequate vitamin D status via supplements, say researchers from Washington University in St Louis.

“There is debate about whether any amount of sun exposure is safe, so oral vitamin D supplements may work best,” said Bernal-Mizrachi.

Vitamin D refers to two biologically inactive precursors – D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive. The latter is derived from plants and only enters the body via the diet, from consumption of foods such as oily fish, egg yolk and liver.

Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active ’storage’ form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.

In adults, it is said vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 diabetes.

Study details

Bernal-Mizrachi and his co-workers obtained macrophage cells from diabetics and non-diabetics, with and without vitamin D deficiency. When the cells were exposed cells to cholesterol and low vitamin D levels, they found that low vitamin D levels in the culture dish resulted in fewer macrophages becoming foam cells.

On the other hand, when the human macrophages were placed in a vitamin D-rich environment, the uptake of cholesterol was suppressed, and they don’t become foam cells, said Bernal-Mizrachi.

The researchers noted that it may be possible to delay or reverse the development of atherosclerosis in diabetics by helping them regain adequate vitamin D levels.

The next stage in the research is to look at vitamin D-deficient diabetics who also high blood pressure. Bernal-Mizrachi said he wants to learn whether replacing vitamin D will lower blood pressure and improve blood flow.

Diabetic stats

An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.

In the US, there are almost 24 million people with diabetes, equal to 8 per cent of the population. The total costs are thought to be as much as $174 billion, with $116 billion being direct costs from medication, according to 2005-2007 American Diabetes Association figures.

Source: Circulation
Volume 120, Number 8, Pages 687-698, doi:10.1161/CIRCULATIONAHA.109.856070
“1,25 (OH) vitamin D inhibits foam cell formation and suppresses macrophage cholesterol uptake in patients with type 2 diabetes mellitus”
Authors: J. Oh, S. Weng, S.K. Felton, S. Bhandare, A. Riek, B. Butler, B.M. Proctor, M. Petty, Z. Chen, K.B. Schechtman, L. Bernal-Mizrach, C. Bernal-Mizrachi