Researchers funded by the Biotechnology and Biological Sciences Research Council (BBSRC) have found that vitamin D reduces the effects of ageing in mouse eyes and improves the vision of older mice significantly. The researchers hope that this might mean that vitamin D supplements could provide a simple and effective way to combat age-related eye diseases, such as macular degeneration (AMD), in people.
The research was carried out by a team from the Institute of Ophthalmology at University College London and is published in the current issue of the journal Neurobiology of Ageing.
The retina's cells are very heavy energy users, heavier energy users than any other cell type in the body. I did not know that.
Professor Glen Jeffery, who led the work, explains "In the back of the eyes of mammals, like mice and humans, is a layer of tissue called the retina. Cells in the retina detect light as it comes into the eyes and then send messages to the brain, which is how we see. This is a demanding job, and the retina actually requires proportionally more energy than any other tissue in the body, so it has to have a good supply of blood. However, with ageing the high energy demand produces debris and there is progressive inflammation even in normal animals. In humans this can result in a decline of up to 30% in the numbers of light receptive cells in the eye by the time we are 70 and so lead to poorer vision."
We need cell therapies to replace tired eye blood vessels, rod cells, cone cells, and other retinal cells. The inflammation and decline in number of light receptive cells with age could be reversed and some day will be reserved. Faster please, as Glenn Reynolds likes to say.
The vitamin D reduced both inflammation and amyloid beta.
The researchers found that when old mice were given vitamin D for just six weeks, inflammation was reduced, the debris partially removed, and tests showed that their vision was improved.
The researchers identified two changes taking place in the eyes of the mice that they think accounted for this improvement. Firstly, the number of potentially damaging cells, called macrophages, were reduced considerably in the eyes of the mice given vitamin D. Macrophages are an important component of our immune systems where they work to fight off infections. However in combating threats to the aged body they can sometimes bring about damage and inflammation. Giving mice vitamin D not only led to reduced numbers of macrophages in the eye, but also triggered the remaining macrophages to change to a different configuration. Rather than damaging the eye the researchers think that in their new configuration macrophages actively worked to reduce inflammation and clear up debris.
The second change the researchers saw in the eyes of mice given vitamin D was a reduction in deposits of a toxic molecule called amyloid beta that accumulates with age. Inflammation and the accumulation of amyloid beta are known to contribute, in humans, to an increased risk of age-related macular degeneration (AMD), the largest cause of blindness in people over 50 in the developed world. The researchers think that, based on their findings in mice, giving vitamin D supplements to people who are at risk of AMD might be a simple way of helping to prevent the disease.
This result is consistent with earlier research on humans that found that higher blood vitamin D levels are associated with a lower risk of age-related macular degeneration. Also, higher vitamin D is associated with healthier blood vessels.
Some evidence exists that too much vitamin D increases risk of atrial fibrillation. But the levels associated with healthier blood vessels and lower AMD risk in humans are below those found to increase atrial fibrillation. So this makes me think there's some value in getting one's vitamin D levels tested and then supplement as necessary to keep one's blood vitamin D in the normal (41-80 ng/dl) range.
BOSTON (July 1) -- Eating a diet high in vitamin D, as well as the nutrients betaine and methionine, might help reduce the risk of macular degeneration, according to new research conducted by Tufts Medical Center scientists. Their study of identical twins from the US World War II Twin Registry also found that the more a person smoked, the higher their risk of developing macular degeneration. The study, "Smoking, Dietary Betaine, Methionine, and Vitamin D in Monozygotic Twins with Discordant Macular Degeneration: Epigenetic Implications” published in the journal Ophthalmology on July 1, is the first to look at identical twin pairs in which one twin had early age-related macular degeneration (AMD), and the other had late stage AMD.
Eat your spinach with fish or poultry.
Similarly, Dr. Seddon’s research team also found that higher intakes of betaine and methionine were linked to a slower progression of the disease. These nutrients have also been linked to epigenetic mechanisms, which is a change in DNA, not attributable to a change in the actual DNA sequence. Betaine is found in fish, grains and spinach, while methionine is found in poultry, fish and dairy foods.
Hey, time for another "vitamin D is good for you" post. Been too long since the last one. This time you can see the benefit.
"In women younger than 75, those who had 25-hydroxyvitamin D concentrations lower than 38 nanomoles per liter were more likely to have age-related macular degeneration than women with concentrations greater than 38 nanomoles per liter," says Amy E. Millen, PhD, assistant professor in the UB School of Public Health and Health Professions and lead author. "Blood concentrations above 38 nanomoles per liter were associated with at least a 44 percent decreased odds of having AMD."
Of course, this is not a double blind longitudinal intervention study with pills. So other factors might both cut eye risk and raise vitamin D levels. But while we wait for results of more definitive studies our eyes will (regrettably) age.
In women younger than 75 years, intake of vitamin D from foods and supplements was associated with decreased risk of developing early AMD. Women who consumed the most vitamin D had a 59 percent decreased odds of developing early AMD compared with women who consumed the least vitamin D. The top food sources of vitamin D in the sample were milk, fish, fortified margarine and fortified cereal. No relationship was observed using self-reported time spent in direct sunlight.
Measures to slow our eye aging aren't the final answer. What we need: Full body repair. If we only had a time machine some of us could travel up ahead 50 years, hop out, and get cell therapies, gene therapies, and growth of replacement organs.
Researchers at Wilmer Eye Institute, Johns Hopkins School of Medicine, wanted to know how the risk of age-related macular degeneration (AMD) would be affected in a population of older people who regularly ate fish and seafood, since some varieties are good sources of omega-3 fatty acids. A diet rich in omega-3s probably protects against advanced AMD, the leading cause of blindness in whites in the United States, according to the Age-Related Eye Disease Study (AREDS) and other recent studies. High concentrations of omega-3s have been found in the eye's retina, and evidence is mounting that the nutrient may be essential to eye health. The new research, led by Sheila K. West, PhD, was part of the Salisbury Eye Evaluation (SEE) study.
Food intake information with details on fish and shellfish consumed was collected over one year using a validated questionnaire for 2,391 participants aged 65 to 84 years who lived along Maryland's Eastern Shore. After dietary assessment was complete, participants were evaluated for AMD. Those with no AMD were classified as controls (1,942 persons), 227 had early AMD, 153 had intermediate-stage disease, and 68 had advanced AMD. In the advanced AMD group, the macular area of the retina exhibited either neovascularization (abnormal blood vessel growth and bleeding) or a condition called geographic atrophy. Both conditions can result in blindness or severe vision loss.
Other evidence for this benefit has been found. Also see my previous reports Eye Aging Slowed By Omega 3 Fatty Acids and Omega 3 Fatty Acids Slow Age-Related Macular Degeneration.
Researchers at the University of Catania in Italy found that at least in tissue culture carnosine prevents the formation of cataract protein clumps.
In the new study, Enrico Rizzarelli and colleagues note that the only effective treatment for cataracts is surgical replacement of the lens, the clear disc-like structure inside the eye that focuses light on the nerve tissue in the back of the eye. Cataracts develop when the main structural protein in the lens, alpha-crystallin, forms abnormal clumps. The clumps make the lens cloudy and impair vision. Previous studies hinted that carnosine may help block the formation of these clumps.
The scientists exposed tissue cultures of healthy rat lenses to either guanidine — a substance known to form cataracts — or a combination of guanidine and carnosine. The guanidine lenses became completely cloudy, while the guanidine/carnosine lenses developed 50 to 60 percent less cloudiness. Carnosine also restored most of the clarity to clouded lenses. The results demonstrate the potential of using carnosine for preventing and treating cataracts, the scientists say.
The key question: can supplementation increase carnosine concentration in vivo (in your body) around the eye lens enough to slow or prevent the development of cataracts? A lot of biochemicals have regulatory mechanisms that control their concentration ranges in in the body. Take too much and the chemical gets broken down or excreted or shifted to other parts of the body.
One also wonders whether carnosine in eye drops would help.
What I also wonder: Suppose scientists succeed in developing ways to grow replacement lenses in laboratories. Can implanted lenses work as well as original lenses? Do they anchor well?
We also need stem cell therapies to rejuvenate muscles around the eye. I expect such cell therapies to reduce the need for reading glasses as stronger eye muscles improve our ability to focus.
BOSTON (June 18, 2009) - Omega-3 fatty acids found in fatty fish such as tuna and salmon may protect against progression of age-related macular degeneration (AMD), but the benefits appear to depend on the stage of disease and whether certain supplements are taken, report researchers at the Laboratory for Nutrition and Vision Research (LNVR), Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University.
The researchers calculated intakes of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from dietary questionnaires administered to 2,924 men and women, aged 55 to 80 years, participating in an eight-year supplement trial, the Age-Related Eye Disease Study (AREDS) of the National Eye Institute (NEI). The AREDS trial results suggest taking supplements of antioxidants plus zinc prevents progression of late-stage AMD. AREDS study participants were randomly allocated to receive either a placebo or supplements containing the antioxidants vitamins C and E and beta carotene, the minerals zinc and copper, or a combination of both.
"In our study, we observed participants with early stages of AMD in the placebo group benefited from higher intake of DHA, but it appears that the high-dose supplements of the antioxidants and/or the minerals somehow interfered with the benefits of DHA against early AMD progression," says senior author Allen Taylor, PhD, director of the LNVR at the USDA HNRCA. Taylor is also a professor at the Friedman School of Nutrition Science and Policy at Tufts and Tufts University School of Medicine (TUSM).
The supplements interfere with the protective effects of DHA and EPA at the early stages of AMD progression, not in the later stages.
The antioxidant supplements did not seem to interfere with the protective effects of DHA and EPA against progression to advanced stages of AMD. Participants who consumed higher amounts of DHA and EPA appeared to have lower risk of progression to both wet and dry forms of advanced AMD. The results are published on-line ahead of print in the British Journal of Ophthalmology.
A low glycemic index diet (basically sugars in forms that are slow to break down and be absorbed) provides additional protective effect.
"Data from the present study also shows the supplements and omega-3 fatty acids collaborate with low-dietary glycemic index (dGI) diets against progression to advanced AMD," says corresponding author Chung-Jung Chiu, DDS, PhD, a scientist in the LNVR and an assistant professor at TUSM. "Our previous research suggests a low-GI diet may prevent AMD from progressing to the advanced stage. We hypothesize that the rapid rise of blood glucose initiated by high-GI foods results in cellular damage that retinal cells cannot handle, thus damaging eye tissues."
Take home lesson: get more omega 3 fatty acids in your diet. Also, learn how to eat a low glycemic index diet. Also, the benefits of antioxidant vitamins are overrated.
Professor Chakravarthy, who is also a Consultant Ophthalmic Surgeon at the Royal Hospital in Belfast, said: "Late AMD causes severe sight loss and has a huge economic impact both in terms of the effects of sight loss itself and in terms of the expensive treatments that are needed to deal with the condition.
"Up to 500 people a year in Northern Ireland will lose sight in one or both eyes as a result of late AMD.
"We wanted to carry out the study as prevention of progression to late AMD can result in a reduced financial and societal burden."
As the macula of the eye is very rich in antioxidants the researchers wanted to see if a supplement called CARMA (Caroteneoids and Co-antioxidants in Age-related Maculopathy) containing the carotenoids lutein and zeaxanthin could help slow down AMD.
The supplement also contained vitamins C,E and Zinc, which had been used in a previous study.
The latest study showed that intake of high levels of both carotenoids preserved the macular pigments, slowing down the progression from early AMD to late AMD.
Progression to both dry and wet forms of advanced AMD disease was 25% less likely among those eating a diet rich in omega-3 fatty acids.
People with advanced AMD who also consumed a low-GI diet, eating of foods that release their sugar more slowly, and who took supplemental antioxidant vitamins and minerals like vitamin C and zinc appeared to reduce their risk of disease progression by even more - by up to 50%.
Substituting five slices of wholegrain bread for white bread every day out of a total intake of 250g of carbohydrate might cut out almost 8% of advanced age related macular degeneration over five years, say the authors.
The top quartiles of consumption of omega 3 fatty acids DHA and EPA were only over 64 and 42 mg per day respectively. These aren't high doses.
While the omega 3 fatty acids help at all stages of the disease the vitamins and minerals actually seem to speed up the disease in its early stages.
And Elaine W. T. Chong, MD, PhD, of the University of Melbourne and colleagues, in their study of more than 6,700 58- to 69-year-olds, found those who consumed the most omega-3 fatty acids were at 15% lower risk of early-stage AMD. People who ate the most olive oil (at least 100 milliliters, or about seven tablespoons, per week) were about half as likely to develop late AMD as those who consumed less than 1 mL per week.
Dr. Chong and her team also found people who ate the most trans fat were 1.76 times more likely to develop late AMD during the study’s follow-up period.
Olive oil helps more than omega 3 fatty acids? Well, consume them both. I'm eating olives in my lunches now. Mu guess is that whole olives deliver a bigger benefit than the same number of calories as olive oil.
Eyesight is a terrible thing to waste. Choose your oils wisely. Then look at beautiful things.
Regularly eating fish, nuts, olive oil and other foods containing omega-three fatty acids and avoiding trans fats appears to be associated with a lower risk for the eye disease age-related macular degeneration, according to two reports in the May issue of Archives of Ophthalmology, one of the JAMA/Archives journals.
By 2020, as many as 3 million Americans are expected to have late-stage age-related macular degeneration (AMD), according to background information in one of the articles. AMD is the leading cause of severe vision loss among individuals older than 65 in the developed world. Established risk factors include age, genetic markers and smoking (the only consistently reported modifiable risk factor).
In one report, Jennifer S.L. Tan, M.B.B.S., B.E., of Westmead Hospital, University of Sydney, Australia, and colleagues studied 2,454 participants in the Blue Mountains Eye Study, which began in 1992 to 1994. At that time, participants completed a food frequency questionnaire that was analyzed to determine their intake of various fatty acids. Digital photographs of the retina were used to assess the development of AMD five and 10 years later.
After adjusting for age, sex and smoking, eating one serving of fish per week was associated with a 31 percent lower risk of developing early AMD. The association was stronger among individuals with a lower intake of linoleic acid, an unsaturated omega-6 fatty acid found primarily in vegetable oils. Eating one to two servings of nuts per week was associated with a 35 percent lower risk of early AMD.
My question: Can one scale up one's omega 3 consumption to counterbalance the effects of consuming larger amounts of omega 6 fatty acids?
I periodically tweak my diet to improve it in various ways. One of my recent additions is to use olives as condiments on my lunch. I am guessing that the whole olives are more beneficial than just the olive oil since the olives will contain more of the non-oil compounds that are suspected of delivering additional health benefits. Get the beneficial oils but with more other good stuff.
A European study suggests that the combination of low plasma levels of antioxidants and blue light exposure from the sun is associated with certain forms of the eye disease age-related macular degeneration (AMD), according to a report in the October issue of Archives of Ophthalmology, one of the JAMA/Archives journals.
"The retina is vulnerable to the damaging effects of light," the authors write as background information in the article. "While wavelengths in the UV radiation range are largely absorbed by the cornea and lens, the retina is exposed to visible light, including blue light." Animal and laboratory studies suggest blue light may damage the retina and contribute to the development of AMD, which occurs when the area of the retina (macula) responsible for sharp vision deteriorates.
Antioxidant enzymes—including vitamins C and E, the carotenoids (lutein and zeaxanthin) and zinc—may protect against the harmful effects of blue light on the retina. Astrid E. Fletcher, Ph.D., of the London School of Hygiene & Tropical Medicine, and colleagues measured levels of these nutrients in the blood of 4,753 older adults (average age 73.2) who were part of the European Eye Study. Participants also were interviewed about their lifetime sunlight exposure and had photographs taken of their retinas to detect AMD.
Of the 4,400 participants with complete information available, 2,117 did not have AMD, 101 had neovascular (advanced, involving the formation of new blood vessels) AMD and 2,182 had early-stage AMD. Overall, there was no association between blue light exposure and neovascular or early AMD. However, blue light exposure was associated with neovascular AMD in the one-fourth of individuals with lowest antioxidant levels. "In particular, the combination of blue light exposure in the presence of low levels of zeaxanthin, alpha-tocopherol [vitamin E] and vitamin C was associated with a nearly four-fold odds ratio of neovascular AMD," the authors write.
The zeaxanthin comes from kale, collard greens, and other green leafy vegetables. Those same veggies are good sources of vitamin K which might slow brain aging due to myelin decay. Vegetables are good for you. But you already knew that. What would it take to get you to eat more vegetables?
Eating fish and other foods high in omega-3 fatty acids is associated with reduced risk of the eye disease age-related macular degeneration (AMD), according to a meta-analysis of nine previously published studies in the June issue of Archives of Ophthalmology, one of the JAMA/Archives journals. However, the accumulated evidence includes few clinical trials and is insufficient to support the routine consumption of such foods for AMD prevention, the authors note.
"Age-related macular degeneration (AMD) is the leading cause of severe vision loss among elderly people," they write as background information in the article. New treatments for AMD are potentially risky and treat only certain forms of the disease. "Thus, primary prevention of AMD by modifying risk factors (e.g., cigarette smoking) remains an important public health strategy."
Elaine W-T. Chong, M.B.B.S., of the University of Melbourne, Australia, and colleagues conducted a systematic review of studies published before May 2007 evaluating the fish consumption and overall omega-3 fatty acid intake for the prevention of AMD. A total of nine studies were identified with 88,974 participants, including 3,203 individuals with AMD.
When results from all nine studies were combined, a high dietary intake of omega-3 fatty acids was associated with a 38 percent reduction in the risk of late (more advanced) AMD, while eating fish twice a week was associated with a reduced risk of both early and late AMD.
The DHA (docosahexaenoic acid) in fish oil is a component of the retina. It also gets used in brain membranes.
Low serum concentration of vitamin E, an indication of poor nutrition, is associated with physical decline for older persons, according to a study in the January 23 issue of JAMA.
“The decline in physical function that occurs with aging often represents the early stage of a continuum leading to disability and other important adverse outcomes such as institutionalization,” the authors write. Understanding the mechanisms associated with this process has been identified as a priority. The potential harmful effect of poor nutrition on physical function in older persons is not well understood.
Benedetta Bartali, R.D., Ph.D., of Yale University School of Medicine, New Haven, Conn., and colleagues conducted a study to determine whether a low concentration of specific micronutrients is associated with subsequent decline in physical function. The study included 698 community-living persons 65 years or older who were randomly selected from a population registry in Tuscany, Italy. To measure nutritional status and physical function, participants completed a baseline examination, conducted from November 1998 through May 2000, and 3-year follow-up assessments from November 2001 through March 2003. Measurements were obtained for several micronutrients, including serum folate and vitamins B6, B12, D and E. Decline in physical function was defined as a loss of at least 1 point in the Short Physical Performance Battery during the follow-up, which included three objective tests of physical function.
The average decline in physical function score was 1.1 point. In analyses adjusted for other factors, only a low concentration of vitamin E was significantly associated with subsequent decline in physical function. Additional analyses indicated that age older than 81 years and vitamin E (in participants 70-80 years) were the strongest determinants of decline in physical function.
“The hypothesis that antioxidants [such as vitamin E] play a role in the etiology of decline in physical function and disability is supported by our previous findings and other studies suggesting that oxidative stress is involved in muscle fatigue and that antioxidants play a preventive role in muscle damage by reducing oxidative injury,” the authors write.
“Thus, at least 3 different mechanisms may explain the effect of low concentration of vitamin E on subsequent decline in physical function: (1) increased oxidative stress leading to muscle or DNA damage, (2) exacerbation of atherosclerosis or other pathologic conditions, and (3) development of neurodegenerative disorders.”
Participants in the study did not take vitamin supplements and the authors do not recommend vitamin E supplements to increase levels. They state, “Approximately 15 to 30 mg/d of dietary alpha-tocopherol [a component of vitamin E] is needed … this amount can be easily reached through diet, from sources such as almonds, tomato sauce, and sunflower seeds among others.”
Can you be bothered to improve your diet? It probably won't pay off much for years. Can you make a sustained change for a distant pay-off?
Eat some nuts. They have magnesium too.
Women who have higher dietary intake of lutein and zeaxanthin—compounds found in yellow or dark, leafy vegetables—as well as more vitamin E from food and supplements appear to have a lower risk for developing cataracts, according to a report in the January issue of Archives of Ophthalmology, one of the JAMA/Archives journals.
“The oxidative hypothesis of cataract formation posits that reactive oxygen species can damage lens proteins and fiber cell membranes and that nutrients with antioxidant capabilities can protect against these changes,” the authors write as background information in the article. Vitamin E, vitamin C, beta carotene, lutein and zeaxanthin are all believed to have antioxidant properties. Lutein and zeaxanthin are the only carotenoids—yellow plant pigments—present in the lens of the human eye and may also protect against cataracts by filtering harmful blue light.
William G. Christen, Sc.D., of Brigham & Women’s Hospital and Harvard Medical School, Boston, and colleagues analyzed dietary information from 35,551 female health professionals who enrolled in the Women’s Health Study in 1993. The women were then followed for an average of 10 years, and the diets of those who developed cataracts were compared with the diets of those who did not.
A total of 2,031 women developed cataracts during the study. When the participants were split into five groups based on the amount of lutein and zeaxanthin they consumed, those in the group who consumed the most (about 6,716 micrograms per day) had an 18 percent lower chance of developing cataracts than those who consumed the least (1,177 micrograms per day). The one-fifth who consumed the most vitamin E from food and supplements—about 262.4 milligrams per day—were 14 percent less likely than the one-fifth who got the least (4.4 milligrams per day).
Of course getting lots of vegetables will reduce your risk of many other diseases as well. But people like the taste of cheeseburgers and fries more than veggies.
Eating fewer refined carbohydrates may slow the progression of age-related macular degeneration (AMD), according to a new study from researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.
AMD results in partial or total blindness in 7 to 15% of the elderly, according to the Eye Diseases Prevalence Research Group. “Dietary changes may be the most practical and cost-effective prevention method to combat progression of AMD,” says Allen Taylor, PhD, director of the Laboratory for Nutrition and Vision Research at the USDA HNRCA. “It is surprising there is so little attention focused on the relationship between AMD and carbohydrates.”
The current study, published in the October issue of the American Journal of Clinical Nutrition, builds on a recent analysis by Taylor and colleagues that found men and women older than 55 who consumed diets with higher-than-average dietary glycemic index foods appeared to have an increased risk for both early and later stages of AMD.
Eat less white bread and more whole grains. Or shift from grains toward beans and the lower glycemic index rices (not that fluffy stuff you find in Chinese restaurants).
A lower glycemic index diet which slows and delays development of AMD probably has more general effects on the rate of aging through out the body.
“Our data showed those people in the high-glycemic-index group were at greater risk of AMD progression, especially those already in the late stages,” says first author Chung-Jung Chiu, DDS, PhD, scientist in the Laboratory for Nutrition and Vision Research at the USDA HNRCA and assistant professor at Tufts University School of Medicine. “Participants who consumed the most refined carbohydrates were 17 percent more likely to develop blinding AMD than the group that consumed the least.”
If you can slow your rate of aging by a small amount doing so might allow you to live long enough to still be alive and mentally mostly intact by the time rejuvenation therapies become available. If you want to shift toward a lower glycemic index diet then see this chart of glycemic index in foods.
BOSTON -- Age-related macular degeneration (AMD) and its associated vision loss may be connected to the quality of carbohydrates an individual consumes. In a study published in the July issue of the American Journal of Clinical Nutrition, Allen Taylor, PhD, director of the Laboratory for Nutrition and Vision Research at the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University, and colleagues confirmed earlier findings linking dietary glycemic index with the risk of developing AMD.
"Men and women who consumed diets with a higher glycemic index than average for their gender and age-group were at greater risk of developing advanced AMD," corresponding author Taylor says. "The severity of AMD increased with increasing dietary glycemic index."
The carbohydrates in lower glycemic index foods break down more slowly into simple sugars in the digestive tract. Therefore the sugar enters the bloodstream more slowly and blood sugar levels do not spike as high. It is those high blood sugar level spikes that cause damage to eyes and to other parts of the body. For this reason diabetics age more rapidly and suffer from blindness, loss of circulation in the extremities, and other problems. We can probably expect a lower glycemic index diet to reduce the incidence of some of the diseases that plague diabetics.
It is worth noting that people who eat lower glycemic index diets are typically eating more vegetables and whole grains that contain assorted beneficial compounds. So I don't think we can be certain whether the benefit reported here is totally due to the lower glycemic. However, it doesn't matter in one sense. If you eat the vegetables that lower dietary glycemic index you'll get the benefits regardless of the mechanisms of action.
Glycemic index is a scale applied to foods based on how quickly the carbohydrates in foods are converted to blood sugar, or glucose. Foods like white rice, pasta and bread are examples of foods with a high-glycemic-index, meaning that these foods are associated with a faster rise and subsequent drop in blood sugar. Whole wheat versions of rice, pasta and bread are examples of foods that have a low-glycemic-index. These foods are often considered higher quality carbohydrates because they are associated with a slower and less dramatic rise and fall of blood sugar.
Rices come in a large range of glycemic indexes. The sticky rice found in Chinese restaurants has one of the high glycemic indexes. Basmati rice is much lower and Uncle Ben's Converted Rice lower still. But grains including rice are generally higher in glycemic than beans and vegetables. If you want to eat a low glycemic index diet best to cut way back on grains and eat more beans, vegetables, and fruits.
Eating a lower glycemic index diet could probably cut your AMD risk by 20% and maybe more.
"Although carbohydrate quality was not the main focus in the AREDS, we were fortunate that the investigators had collected the dietary carbohydrate information we needed to do our analyses," says Taylor, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts and the Tufts University School of Medicine. "Our findings suggest that 20 percent of the cases of advanced AMD might have been prevented if those individuals had consumed a diet with a glycemic index below the average for their age and gender," notes Taylor.
The mechanism by which high glycemic index foods boost your risk of blindness also probably does damage in other parts of your body. So lowering your diet's average glycemic index will deliver other benefits. Plus, if you lower your glycemic index by eating more vegetables you'll benefit from vitamins and assorted other beneficial nutrients found in vegetables.
Check out David Mendosa's chart of glycemic index and glycemic load for hundreds of foods.
Update: Another way to reduce the risk of AMD: genetically engineer yourself to have genes that lower your risk of AMD.
They found that a variant in the complement C3 gene influenced the risk of developing AMD. For the 30% of the population who carry one copy of the so-called ‘fast’ variant the risk of AMD was increased by 70%, and for the 4% of people with two copies of the ‘fast’ variant the risk of AMD was more than doubled.
AMD can take two forms called ‘wet’ (also called choroidal neovascularisation or CNV) and ‘dry’ (also called geographic atrophy or GA). The ‘fast’ variant in the C3 gene increases the risk of both forms of the disease.
The complement C3 gene has a central role in the immune system. The results of this research provide strong evidence that inflammation is an important part of the disease process in AMD.
I think we are going to find that the diseases in our ancestral past selected for humans who have over-enthusiastic immune systems that cause damaging inflammation.
Previous studies have suggested a potential link between AMD and lutein and zeaxanthin, plant pigments known as carotenoids and found in leafy green vegetables, corn, egg yolks, squash, broccoli and peas. These compounds may reduce the risk of AMD by absorbing blue light that could damage the macula, by preventing free radicals from damaging eye cells and by strengthening eye cell membranes. Suzen M. Moeller, Ph.D., University of Wisconsin, Madison, and colleagues with the Carotenoids in Age-Related Eye Disease Study (CAREDS) Research Study Group, assessed the effects of dietary lutein plus zeaxanthin in 1,787 women ages 50 to 79 years in Iowa, Wisconsin and Oregon. The women with the highest and lowest dietary intakes of lutein and zeaxanthin in the Women's Health Initiative, a large study of postmenopausal women that began between 1994 and 1998, were recruited to participate in CAREDS. At the beginning of the study, participants filled out a questionnaire to evaluate what their diets were like 15 years before the beginning of the study. Blood samples were taken to assess levels of carotenoids and color photographs of the retina were used to determine the presence and progression of AMD. A higher intake of lutein plus zeaxanthin was associated with a lower risk of intermediate-stage AMD in women younger than age 75 years who had a stable intake of the carotenoids over the 15-year period and did not have previous AMD or a chronic disease, such as cardiovascular disease, diabetes or hypertension, that might alter their dietary habits. However, no significant difference was observed in the overall group of women or when comparing lutein and zeaxanthin levels in the blood to AMD occurrence. There was a weak association between dietary lutein plus zeaxanthin and advanced-stage AMD in all the women and in women younger than age 75 years.
Eat more kale. Per half cup kale is highest with 10 mg lutein and then collard greens with 7.7 mg and spinach with 3.3 mg.
A carotenoid, lutein is found in green vegetables, especially spinach, as well as kale and broccoli. But egg yolks, although they contain significantly less lutein than spinach, are a much more bioavailable source whose consumption increases lutein concentrations in the blood many-fold higher than spinach.
Eat eggs for your eyes.
BOSTON (July 10, 2006) -- Researchers in Boston studied elderly male twins and found that those who smoke or have a history of smoking had an increased risk of developing age-related macular degeneration as compared to those who never smoked. At the same time, those who ate more fish and had diets with higher levels of omega-3 fatty acids reduced their risk of this blinding disease. Their findings are published in the July 2006 issue of the Archives of Ophthalmology.
Researchers at the Massachusetts Eye and Ear Infirmary and Department of Biostatistics at Harvard Medical School studied 681 male twins from the National Academy of Sciences-National Research Council World War II Veteran Twin Registry. To determine genetic and environmental risk factors for AMD, twins were surveyed for a prior diagnosis of AMD and underwent an eye examination, fundus photography, and food frequency and risk factor questionnaires. The study included 222 twins with intermediate and late stage AMD and 459 twins with no signs of the disease.
“Current smokers had a 1.9-fold increased risk of developing AMD, while past smokers had about a 1.7-fold increased risk,” said Johanna M. Seddon, M.D., director of the Epidemiology Unit at the Massachusetts Eye and Ear Infirmary and an associate professor of ophthalmology at Harvard Medical School. “We also found that increased intake of fish reduced the risk of AMD, particularly if they ate two more servings per week. Dietary omega-3 fatty intake was also inversely associated with AMD. This study of twins provides further evidence that cigarette smoking increases risk while fish consumption and omega-3 fatty acid intake reduce risk of AMD.”
The effects of cigarettes are no surprise. Previous studies have shown a beneficial effect of fish for AMD. This study strengthens the evidence for that finding.
The problem: The oceans are getting depleted of fish. We really need genetic engineering done on crop plants in order to make more scalable and cheaper land-based sources of omega 3 fatty acids.
Boston-- Age-related macular degeneration (AMD) is one of the leading causes of vision loss in older adults and a person's risk may partly depend upon diet. When it comes to carbohydrates, quality rather than quantity may be more important, according to new research by Allen Taylor, PhD, director of the Laboratory for Nutrition and Vision Research at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University, and colleagues. Their findings were reported in the April 2006 issue of the American Journal of Clinical Nutrition.
Taylor and colleagues analyzed data from a sub-group of participants in the Nurses' Health Study (NHS) who were enrolled in the Nutrition and Vision Program. The researchers looked at the total amount of carbohydrates consumed over 10 years and the dietary glycemic index, which is a measure of the quality of overall dietary carbohydrate.
"Women who consumed diets with a relatively high dietary glycemic index had greater risk of developing signs of early age-related macular degeneration when compared with women who consumed diets with a lower dietary glycemic index," says lead author Chung-Jung Chiu, DDS, PhD, scientist in the Laboratory for Nutrition and Vision Research at the HNRCA and an assistant professor at Tufts University School of Medicine. High total carbohydrate intake, however, did not significantly increase the risk factor for AMD.
"In other words, the types of carbohydrates being consumed were more important than the absolute amount," explains Taylor, senior author. A high-glycemic-index diet is one that is rich in high-glycemic-index foods, which are converted more rapidly to blood sugar in the body than are low-glycemic-index foods.
You can lower your average dietary glycemic index in all sorts of ways. For example, the sticky rice served in Chinese restaurants has a very high glycemic index (i.e. it gets digested and the sugar in it passes into your bloodstream very quickly). Whereas Basmati rice is much lower and Uncle Ben's converted rice is lower stilll. Similarly, the types of wheat used to make bread have much higher glycemic index than the types of wheat used to make pasta and whole grain generally is lower than white bread. The idea where is that you don't have to give up a major grain. You can just shift toward subtypes that have lower glycemic index.
Rick Mendosa has a great online list of foods and their glycemic indexes. Go study it. Also, read his introduction to glycemic index which offers all sorts of insights about why foods vary in glycemic index. Note that in the scaling he uses 100 is the index for glucose. The low range starts at 55 and goes down into the 30s and 40s for some grains and beans. Higher amylose grains have lower glycemic indexes because amylose starch is broken down fairly slowly in the digestive tract. I wish rices came with an amylose rating on the bag. Then purchase of a rice with 27% or 28% amylose would assure you are getting a low glycemic index variety. Note how he lists a low amylose corn muffin with a glycemic index of 102 and a high amylose corn muffin with a glycemic index of 49. Huge difference. Though the latter number might be due to rolled oats in the recipe.
The Wikipedia Glycemic Index page is worth a read as well.
A diet with a high intake of beta carotene, vitamins C and E, and zinc is associated with a substantially reduced risk of age-related macular degeneration in elderly persons, according to a study in the December 28 issue of JAMA.
Age-related macular degeneration (AMD) is a degenerative disorder of the macula, the central part of the retina, and is the most common cause of irreversible blindness in developed countries, according to background information in the article. Late-stage AMD results in an inability to read, recognize faces, drive, or move freely. The prevalence of late AMD steeply increases with age, affecting 11.5 percent of white persons older than 80 years. In the absence of effective treatment for AMD, the number of patients severely disabled by late-stage AMD is expected to increase in the next 20 years by more than 50 percent to 3 million in the United States alone. Epidemiological studies evaluating both dietary intake and serum levels of antioxidant vitamins and AMD have provided conflicting results. One study (called AREDS) showed that supplements containing 5 to 13 times the recommended daily allowance of beta carotene, vitamins C and E, and zinc given to participants with early or single eye late AMD resulted in a 25 percent reduction in the 5-year progression to late AMD.
Redmer van Leeuwen, M.D., Ph.D., of Erasmus Medical Centre, Rotterdam, the Netherlands, and colleagues investigated whether antioxidants, as present in normal daily foods, play a role in the primary prevention of AMD. Dietary intake was assessed at baseline in the Rotterdam Study (1990-1993) using a semiquantitative food frequency questionnaire. Follow-up continued through 2004. The Rotterdam Study included inhabitants aged 55 years or older from a middle-class suburb of Rotterdam, the Netherlands. Of 5,836 persons at risk of AMD at baseline, 4,765 had reliable dietary data and 4,170 participated in the follow-up.
Average follow-up of participants was 8.0 years. During this period, 560 persons (13.4 percent) were diagnosed as having new AMD, the majority of whom had early-stage AMD. A significant inverse association was observed for intake of vitamin E, iron, and zinc. After adjustment, a 1-standard deviation increase in intake was associated with a reduced risk of AMD of 8 percent for vitamin E and 9 percent for zinc. An above-median (midpoint) intake of beta carotene, vitamins C and E, and zinc, compared with a below-median intake of at least 1 of these nutrients, was associated with a 35 percent reduced risk of AMD, adjusted for all potential confounders. In persons with a below-median intake of all 4 nutrients, the risk of AMD was increased by 20 percent. Adding nutritional supplement users to the highest quartile of dietary intake did not change the results.
The benefit of the nutrients is higher when the nutrients come from foods.
"This study suggests that the risk of AMD can be modified by diet; in particular, by dietary vitamin E and zinc. A higher intake of vitamin E can be achieved by consumption of whole grains, vegetable oil, eggs, and nuts. High concentrations of zinc can be found in meat, poultry, fish, whole grains, and dairy products. Carrots, kale, and spinach are the main suppliers of beta carotene, while vitamin C is found in citrus fruits and juices, green peppers, broccoli, and potatoes. Based on this study, foods high in these nutrients appear to be more important than nutritional supplements. Until more definitive data are available, this information may be useful to persons with signs of early AMD or to those with a strong family history of AMD. Although in need of confirmation, our observational data suggest that a high intake of specific antioxidants from a regular diet may delay the development of AMD," the authors conclude.
The foods contain other beneficial compounds and part of the measured benefit associated with high consumption of E, zinc, and so on probably comes from other compounds. For example, foods high in the D-alpha tocopherol form of vitamin E also have other tocopherols and some foods even have the related tocotrienols. Also beta carotenoid is part of a very large family of carotenoids. In addition, healthful foods have a variety of anti-oxidants that are not even related to vitamins.
Improve your diet to increase your odds of living long enough to take advantage of Strategies for Engineered Negligible Senescence. I'm convinced that there are people alive right now who will one day become young again using coming advances in biotechnology. We should all support a big push to make that day come sooner. But while we do that and while we wait for rejuvenation therapies we should eat excellent diets to increase our odds of still being around for that day.