Foods that can help keep your peepers in top shape

Last Updated: Friday, July 10, 2009 | 4:26 PM ET
By Michelle Gelok, CBC News

Science continues to show us that certain nutrients are needed by different areas of the body to boost health and prevent disease. Whether it's the omega-3 fatty acids in fish that boost heart health or the calcium in milk that keeps bones strong, there's no denying the role that food plays in the prevention of disease.

Often overlooked, however, is the role that food plays in keeping our eyes in top form.

Recent research findings published in May in Ophthalmology, the journal of the American Academy of Ophthalmology, are shedding light on the link between diet and eye health.

The study, conducted by researchers at Tufts University in Massachusetts, is the first of its kind to look at the combined effect of nutrients on eye health, and to examine their role in the prevention of age-related macular degeneration (AMD), a leading cause of blindness in adults. Researchers analyzed data from more than 4,000 participants and assessed their intake of nutrients including vitamins C and E, zinc, lutein, zeaxanthin, omega-3 fatty acids and low-glycemic-index foods.
Age-related macular degeneration or AMD.

AMD affects the macula, located in the centre of the retina, which is the part of the eye that allows you to see fine details.

According to the Canadian National Institute for the Blind, more than one million Canadians have AMD.

Each dietary factor was assigned a score, and the scores were totalled and compared to the AMD risk for participants. Researchers found that higher scores were associated with a lower risk of developing AMD. In other words, the higher the intake of protective nutrients, the less likely the participants were to develop AMD.

While these findings are the first to measure the combined effect of protective nutrients, it turns out researchers have been studying each of these nutrients in isolation for years. Here's a rundown of the top nutrients, and their food sources, that have been shown to help keep eyes healthy.
Omega-3s

Omega-3 fatty acids, most popular for their heart health benefits and anti-inflammatory properties, are beginning to make their mark when it comes to keeping our peepers in top form.

A major study published last year in the Archives of Ophthalmology reviewed data from nine studies with a total of more than 88,000 participants. It found that a high intake of omega-3 fatty acids was associated with a 38 per cent reduction in the risk of AMD. Researchers also found that eating fish at least twice a week was associated with a decreased risk of AMD.

The best sources of omega-3 fatty acids include fatty fish such as salmon, mackerel and herring, as well as ground flax seeds, walnuts and soybeans.
Lutein and zeaxanthin

Lutein and zeaxanthin, though they may sound like a tongue twister when said together, are two yellow pigments that get top marks for their link to eye health.

Lutein and zeaxanthin are compounds found in the retina of the eye, as well as some foods. They are actually antioxidants that have been shown to offer protection from both AMD and cataracts by protecting against oxidation of healthy tissue in the eye. One study published in the Archives of Ophthalmology in 2007 found an inverse relationship between the dietary intake of lutein and zeaxanthin and risk for developing AMD. In other words, participants with higher intakes of lutein and zeaxanthin experienced an overall decreased risk of AMD.

Though they are yellow pigments, these two compounds are found in a variety of colourful produce, including spinach, kale, squash, green peas, broccoli and corn.
Vitamin A

Carrots, perhaps the most well known food when it comes to eye health, have long been linked to eyesight - and for good reason. Carrots are an excellent source of beta-carotene, a nutrient converted into vitamin A in the body.

While the study mentioned earlier didn't find a link between vitamin A intake and decreased risk of AMD, one of vitamin A's roles in the body is to help the retina function properly, and this is essential for general eye health. According to the World Health Organization, vitamin A deficiency is the leading cause of preventable blindness in children. A deficiency of this fat-soluble vitamin is also linked to night blindness in adults.

The best dietary source of beta-carotene and vitamin A include organ meats, orange root vegetables (such as carrots), and green leafy vegetables.
Vitamin C

While vitamin C is best known for its ability to help fight off the common cold, it turns out it plays a role in preventing AMD and related vision loss as well.

When combined with vitamin E, beta-carotene and zinc in high doses, vitamin C was found to lower the risk of AMD by 25 per cent in people at high risk for the disease. The clinical trial, called the Age-Related Eye Disease Study (AREDS), which was published in the Archives of Ophthalmology in 2001, also found that this high-dose combination of vitamins and minerals reduced the risk of vision loss caused by AMD by 19 per cent.

Another study, conducted on animals and published in the journal Microvascular Research in 2007 found that long-term vitamin C supplementation might play a role in preventing diabetic retinopathy — a leading cause of blindness in diabetics.

While both studies used vitamin C supplements, until conclusive dosage recommendations are made it's best to stick to food sources to get the amount you need to keep your eyes healthy. Excellent dietary sources of vitamin C include papaya, red bell peppers, kiwi, strawberries and oranges.
Low glycemic index foods

A study published last year in the American Journal of Clinical Nutrition found that the glycemic index (GI), a measure of how quickly carbohydrates raise blood glucose levels, also affected the risk for AMD. Researchers found that a diet rich in high GI foods, those that cause a rapid rise and fall in blood glucose levels, was associated with a greater risk and increased severity of AMD.

The findings aren't entirely surprising, since low GI foods have already been linked to a decreased risk of heart disease and Type 2 diabetes.

High GI foods tend to be highly processed refined foods, such as white bread, French fries and potatoes, whereas low GI foods are higher in fibre, including oat bran, lentils, beans and barley.


The author is a Canadian licensed registered dietitian.


EARN HEALTH & WEALTH

Discovery Shows New Vitamin C Health Benefits

ScienceDaily (Jan. 12, 2005) — CORVALLIS - Researchers in the Linus Pauling Institute at Oregon State University have made a major discovery about the way vitamin C functions in the human body - a breakthrough that may help explain its possible value in preventing cancer and heart disease.
The study, which explores the role of vitamin C in dealing with the toxins that result from fat metabolism, was just published in a professional journal, Proceedings of the National Academy of Sciences.

It contradicts the conclusions of some research that was widely publicized three years ago, which had suggested that this essential nutrient might actually have toxic effects.

The new OSU study confirmed some of the results of that earlier laboratory study, which had found vitamin C to be involved in the formation of compounds potentially damaging to DNA. But that research, scientists say, only provided part of the story about what actually happens in the human body.

The newest findings explain for the first time how vitamin C can react with and neutralize the toxic byproducts of human fat metabolism.

"This is a previously unrecognized function for vitamin C in the human body," said Fred Stevens, an assistant professor in the Linus Pauling Institute. "We knew that vitamin C is an antioxidant that can help neutralize free radicals. But the new discovery indicates it has a complex protective role against toxic compounds formed from oxidized lipids, preventing the genetic damage or inflammation they can cause."

Some earlier studies done in another laboratory had exposed oxidized lipids - which essentially are rancid fats - to vitamin C, and found some reaction products that can cause DNA damage. These test tube studies suggested that vitamin C could actually form "genotoxins" that damage genes and DNA, the types of biological mutations that can precede cancer.

But that study, while valid, does not tell the whole story, the OSU researchers say.

"It's true that vitamin C does react with oxidized lipids to form potential genotoxins," said Balz Frei, professor and director of the Linus Pauling Institute, and co-author on this study. "But the process does not stop there. We found in human studies that the remaining vitamin C in the body continues to react with these toxins to form conjugates - different types of molecules with a covalent bond - that appear to be harmless."

In human tests, the OSU scientists found in blood plasma extraordinarily high levels of these conjugates, which show this protective effect of vitamin C against toxic lipids.

"Prior to this, we never knew what indicators to look for that would demonstrate the protective role of vitamin C against oxidized lipids," Stevens said. "Now that we see them, it becomes very clear how vitamin C can provide a protective role against these oxidized lipids and the toxins derived from them. And this isn't just test tube chemistry, this is the way our bodies work.

"This discovery of a new class of lipid metabolites could be very important in our understanding of this vitamin and the metabolic role it plays," Stevens said. "This appears to be a major pathway by which the body can get rid of the toxic byproducts of fat metabolism, and it clearly could relate to cancer prevention."

Oxidation of lipids has been the focus of considerable research in recent years, the scientists say, not just for the role it may play in cancer but also in other chronic diseases such as heart disease, Alzheimer's disease, and autoimmune disorders.

The toxic products produced by fat oxidation may not only be relevant to genetic damage and cancer, researchers believe, but are also very reactive compounds that damage proteins. For instance, there's a protein in LDL, the "bad" cholesterol in your blood, which if damaged by toxic lipids can increase the chance of atherosclerotic lesions. In continuing research, the OSU team plans to study the role of this newly understood reaction between vitamin C and toxic lipids in atherosclerosis. In clinical studies they plan to examine the blood chemistry of patients who have been diagnosed with coronary artery disease, compared to a healthy control group.

"In the early stages of atherosclerosis, it appears that some of these toxic lipids make white blood cells stick to the arterial wall, and start an inflammatory process that ultimately can lead to heart disease or stroke," Frei said. "When we better understand that process and the role that micronutrients such as vitamin C play in it, there may be strategies we can suggest to prevent this from happening."

The new findings, the OSU scientists say, also point to new biomarkers that can be useful in identifying oxidative stress in the human body. They may provide an indicator of people who may be at special risk of chronic disease.

from: ScienceDaily



Earn Health & Wealth

Berries offer bountiful health benefits

" COST IN NOT IMPORTANT IF WERE TALKING ABOUT HEALTH. THINK OF IT. IT'S NOT TOO LATE"

Whether you grow them, pick them at a “pick-your-own” patch or in the wild, or buy them at grocery stores or farmers markets, berries are good for your health.

Berries are a colorful addition to our plates and contribute cancer-fighting antioxidants, which protect our cells from damage. Blue and red berries get their color from “anthocyanins,” which are natural pigments that act as antioxidants.

Eating a colorful, antioxidant-rich diet may reduce our risk of certain types of cancer and heart disease. In a 2004 U.S. Department of Agriculture study, researchers tested more than 100 commonly eaten foods. The top 11 foods in terms of antioxidant capacity included wild and cultivated blueberries, cranberries, blackberries, raspberries and strawberries.

Naturally sweet berries are a dieter’s dream, too. A cup of blueberries has about 85 calories and a cup of strawberries just 56 calories. Berries provide vitamin C, folate (a B vitamin) and fiber.

Besides helping protect us from cancer and heart disease, berries may protect our brain, too. In studies with mice, blueberry extracts have shown promise in reversing age-related declines in memory.

You may have seen dietary supplements that promise you can skip your fruits and/or veggies and opt for a “fruit and veggie pill” instead. Don’t believe all the dietary supplement claims, though. Fruits and vegetables are complex mixtures of natural chemicals. Nutrition experts recommend enjoying the whole food instead of an isolated substance.

Enjoy more tasty, colorful berries with these tips:

- Wash berries right before eating and clean strawberries with the stem intact.

- Sprinkle some berries on your breakfast cereal.

- No time for breakfast? Place some frozen berries and yogurt in a blender, blend one minute, pour in a cup and be on your way.

- Make a fresh fruit salsa with strawberries, apples and cilantro. Serve as a side dish with grilled fish.

- Make a snack mix with your favorite whole-grain cereal and dried cranberries and blueberries.

- Add blackberries and strawberries to salad greens, such as spinach or romaine.

- Make a parfait by layering berries and fat-free vanilla or lemon yogurt in a glass.

- If you buy extra berries, freeze some to enjoy later. Wash them, blot with a paper towel, lay them in a single layer on a tray, freeze for an hour or two and package in freezer bags labeled with the date.

Wouldn’t some berries be a tasty snack right now? Try this smoothie for a quick breakfast or snack. For more information and recipes,

visit www.ndsu.edu/eatsmart.

Julie Garden-Robinson,
Ph.D., L.R.D.


BUSINESS OPPORTUNITY