What are the best vitamins for eye health?

 Vitamins A, C, and E are essential for maintaining good eye health. B vitamins and other nutrients can also be good for the eyes.

Deficiencies in particular vitamins can increase the risk of some eye conditions, such as cataracts, glaucoma, and age-related macular degeneration. Research suggests that some vitamin and mineral supplements may help protect against or slow the development of these conditions.

This article outlines the vitamins and minerals essential for good eye health and how people can add them to their diet.

Vitamin A and beta carotene

Vitamin A is essentialTrusted Source for good vision. It is a component of the protein rhodopsin, which allows the eye to see in low-light conditions. According to the American Academy of Ophthalmology, a deficiency in vitamin A can lead to night blindness.

Vitamin A also supports the function of the cornea, which is the protective outer layer of the eye. A person who is deficient in vitamin A may find that their eyes produce too little moisture to stay lubricated.

Beta carotene is the primary source of vitamin A in the human diet. Beta carotene is a type of plant pigment called a carotenoid that exists in many colorful fruits and vegetables. When a person consumes carotenoids, their body converts the pigments into vitamin A.

Foods for vitamin A

People can add vitamin A into their diet by eating the following foods:

• sweet potato
• carrots
• red pepper
• pumpkin
• squash

Vitamin E

Alpha tocopherol is a form of vitamin E that has particularly powerful antioxidant properties.

Antioxidants help fight free radicals, which damage tissues throughout the body. Sometimes, free radicals may damage proteins within the eye. This damage can result in the development of cloudy areas — cataracts — on the lens of the eye.

A 2015 meta-analyses concluded that a high intake of vitamin E, whether through the diet or supplementation, may reduce the risk of developing cataracts.

Foods for vitamin E

Foods high in vitamin E include:

• almonds
• sunflower seeds
• peanuts
• safflower oil
• soybean, corn, and wheat germ oil
• asparagus

Vitamin C

Vitamin C plays an important role in the eye itself, protecting against UV light damage. While the concentration of vitamin C in the eyes lessens with age, diet and supplementation can counteract this.

Vitamin C also helps protect against oxidative damage. Oxidative damage is a key factorTrusted Source in two of the most common age-related cataracts: cortical and nuclear cataracts. Cortical cataracts develop on the edges of the lens, while nuclear cataracts occur deep in their center.

A 10-year longitudinal study investigated different factors that may help prevent nuclear cataract development. The study involved more than 1,000 pairs of female twins. At the end of the study period, participants who consumed more vitamin C showed a 33% reduction in the risk of cataract progression. They also had clearer lenses overall.

However, a 2020 reviewTrusted Source concluded that more research is necessaryto fully identify the role of vitamin C as an anticataract therapy.

Foods for vitamin C

The following foods contain high levels of vitamin C:

• oranges and orange juice
• broccoli
• Brussels sprouts
• blackberries
• grapefruit juice

B vitamins

A 2015 reviewTrusted Source found that people with tend to have lower blood B12 levels. However, researchers noted insufficient evidence to confirm a direct link.

However, this particular study only included women. Further research is, therefore, necessary to support the use of B-vitamins in preventing AMD in both males and females.

A 2018 nationwide studyTrusted Source in South Korea found a link between a reduced intake of vitamin B3 (niacin) and glaucoma. In people with glaucoma, a buildup of fluid within the eye puts pressure on the optic nerve. Over time, this can damage the nerve, resulting in vision loss.

A small 2020 study also found that supplementation of vitamin B1 and mecobalamin may reduce symptoms of dry eye disease.

Foods for B vitamins

The following foods contain high levels of various B vitamins:

B Vitamin	Foods
Vitamin B1 (thiamine)	beans, lentils, pork, fish, green peas, yogurt
Vitamin B2 (riboflavin)	beef, oats, yogurt, milk, clams, mushrooms, almonds
Vitamin B3 (niacin)	beef liver, chicken, salmon and tuna, brown and white rice, peanuts
Vitamin B6 (pyridoxine)	chickpeas, dark leafy greens, poultry, beef liver, salmon, and tuna
Vitamin B9 (folic acid)	dark leafy greens, peanuts, beans, seafood, sunflower seeds, eggs
Vitamin B12 (cobalamin)	fish, liver, red meat, poultry, eggs

People who do not consume animal products can easily consume enough vitamin B12 through supplements and fortified foodstuffs.

Further resources

For more in-depth resources about vitamins, minerals, and supplements, visit our dedicated hub.

Other nutrients for eye health

Research suggests that the following nutrients are also beneficial for the eyes.

Lutein and zeaxanthin

Lutein and zeaxanthin are carotenoids that exist in high quantities in green leafy vegetables. They are also present in the lens and retina of the eye.

As antioxidants, lutein and zeaxanthin may help reduce oxidative damage in the retina. Research in 2017Trusted Source suggests that taking approximately 6 milligrams (mg) per day of lutein and zeaxanthin may lower a person’s risk of developing AMD. An intake of 0.5–1 mg per day may also lower the risk of glaucoma.

Sources of lutein and zeaxanthin include:

• egg yolks
• corn
• asparagus
• broccoli
• lettuce
• peas
• kale
• spinach

Zinc

Zinc is a mineral that helps maintain the health of the retina, cell membranes, and protein structure of the eye.

Zinc allows vitamin A to travel from the liver to the retina to produce melanin. Melanin is a pigment that protects the eyes from UV light.

Zinc supplementation may help people who have AMD or are at risk of developing the condition. According to the American Optometric Association, taking 40–80 mg of zinc each day, alongside certain antioxidants, could slow the progression of advanced AMD by 25%. It could also reduce visual acuity loss by 19%.

Sources of zinc include:

• seafood, such as oysters, crab, and lobster
• turkey
• beans
• chickpeas
• nuts
• pumpkin seeds
• whole grains
• milk
• fortified cereals

Omega-3 fatty acids

The retina of the eye contains a high concentration of omega-3 fatty acids. These fatty acids help protect the retina from damage and degeneration. Small animal studies have found that omega-3 supplementation can slow age-related retina degradation. However, further human studies are necessary to fully assess the link.

Many doctors recommendTrusted Source omega-3 fatty acids for the treatment of dry eye syndrome. A person with dry eye syndrome does not produce enough tears to keep the eyes lubricated. However, a large randomized control study found no significant improvement in dry eye symptoms when compared to a placebo.

Foods rich in omega-3 fatty acids include:

• oily fish, such as sardines, tuna, and herring
• flaxseed
• walnuts
• chia seeds

Vitamins and the diet

A healthy, balanced diet can help promote good eye health and protect a person’s vision. A varied diet rich in nutritionally-dense foods can often provide adequate amounts of all vitamins and minerals.

However, some people may require additional supplementation to reach certain nutritional targets if their diet cannot provide this.

In some cases, taking supplements may lead to side effects, so it is important for people to speak with a doctor before making large dietary changes. For example, high dosages of zinc can affect how the body absorbs copper.

Summary

Specific vitamins and nutrients are essential for maintaining good eye health. Some may even help prevent certain eye diseases from developing or progressing.

A healthy, balanced diet will provide people with the necessary range of nutrients. The diet should include whole grains, legumes, and plenty of colorful fruits and vegetables.

Source - Medical News Today

Medical myths: All about allergies

 For Asthma and Allergy Awareness Month, this edition of the Medical Myths series tackles some of the many myths and misconceptions associated with allergies.

In our Medical Myths series, we approach medical misinformation head on. Using expert insight and peer reviewed research to wrestle fact from fiction, MNT brings clarity to the myth riddled world of health journalism.

In brief, an allergy is an unusual or exaggerated immune response triggered by a particular substance. Symptoms often include itchy eyes, wheezing, and sneezing. For many people, allergic reactions are uncomfortable and unpleasant, but they can be life threatening for others.

According to estimates from the Centers for Disease Control and Prevention (CDC), up to 60 millionTrusted Source people in the United States experience allergies each year.

The World Health Organization (WHO) estimates that around 20% of people worldwide have an allergic condition.

One of the most common allergies — hay fever — affected an estimated 19.2 millionTrusted Source adults in the U.S. during 2018, and this figure is likely to rise.

“Allergies are currently on the rise in the U.S.,” explained Dr. Omid Mehdizadeh, an otolaryngologist and laryngologist at Providence Saint John’s Health Center in Santa Monica, CA.

He told Medical News Today that “scientists believe the increasing prevalence of environmental allergies is due to changing weather patterns and increasing pollen blooms in the U.S.”

Considering their prevalence, understanding and dismissing the myths associated with allergies is an important task. Here, we tackle 11 such myths.

1. Allergies only develop in children

One persistent myth is that once you reach adulthood, you don’t develop any more allergies. This is untrue.

One studyTrusted Source, for instance, looked at the prevalence of food allergies in 40,443 adults in the U.S. At the time of the survey, 10.8% of participants had a food allergy.

The authors found that in around half of these individuals with food allergies, at least one of these food allergies developed during adulthood.

2. There are no treatments for allergies

In general, the best way to minimize allergic reactions is to avoid triggers, whether a particular food or a type of animal. There are no cures for allergies.

However, certain treatments can effectively reduce the symptoms. For instance, decongestants can relieve the nasal symptoms of allergies, while antihistamines and nasal steroid sprays can also be effective.

Additionally, allergy immunotherapy can help reduce allergies. The American College of Allergy, Asthma, and Immunology states:

“Immunotherapy involves giving gradually increasing doses of the substance, or allergen, to which the person is allergic. The incremental increases of the allergen cause the immune system to become less sensitive to the substance, probably by causing production of a ‘blocking’ antibody, which reduces the symptoms of allergy when the substance is encountered in the future.”

3. Food allergies and food intolerances are the same

This is not true: food allergies and food intolerances are different. When someone experiences a food allergy, it is driven by their immune systemTrusted Source, usually associated with the action of Immunoglobulin E (IgE).

During an IgE-mediated immune responseTrusted Source, IgE binds to receptors on specific cells, including mast cells and basophils. These cells then produce histamine and other compounds, causing symptoms to appear very rapidly.

On the other hand, intolerances do not involve the immune system, and symptoms take longer to appear. And while intolerances are not life threatening, food allergies can be in some cases.

4. Allergies are for life

Thankfully, this is a myth. Although some allergies do persist for life, as Dr. Mehdizadeh told MNT, “Some allergies may simply dissipate with age.”

Whether an allergy diminishes over time can depend on the allergen. The authors of a review on food allergies explain:

“Although most children ‘outgrow’ allergies to milk, egg, soy, and wheat, allergies to peanut, tree nuts, fish, and shellfish are often lifelong.”

5. Peanut allergies are the most serious

Although peanut allergies are common — affecting an estimated 6.1 million people in the U.S. — and can certainly be dangerous, there is no way to rank allergy severity. Some individuals might have only a mild reaction to peanuts but, for others, it could spark anaphylaxis.

Although certain foods, such as tree nuts, shellfish, and eggs, account for most allergies, virtually any food can trigger a reaction. The severity of the reaction depends on an individual’s immune system.

6. Colds and allergies are the same

Although colds and allergies can share certain symptoms, including a blocked nose and runny eyes, they are different. Symptoms of a cold are caused by an immune response to viruses, while allergies are an immune response to an allergen.

Another important difference is that colds tend to last around 1–2 weeks, whereas allergies can, in some cases, last a lifetime.

7. Short-haired cats and dogs don’t trigger allergies

This is not true. For some people, certain breeds may be less likely to trigger allergies, but there are no hard and fast rules. Allergies are not triggered by an animal’s hair — they are set off by dead skin cells (dander), saliva, and urine.

Additionally, as the American Academy of Allergy, Asthma, and Immunology (AAAAI) explains, “pet hair or fur can collect pollen, mold spores, and other outdoor allergens.”

8. Hypoallergenic breeds

Many people believe that certain cat and dog breeds are “hypoallergenic,” meaning they do not trigger allergies. However, this is a myth. As the AAAAI explains:

“Contrary to popular opinion, there are no truly ‘hypoallergenic breeds’ of dogs or cats. Allergic dander in cats and dogs is not affected by length of hair or fur, nor by the amount of shedding.”

9. Continuous exposure to animals reduces allergies

There is a common theory that if someone with an animal allergy spends time with that type of animal, the allergy will slowly improve. But this is not the case. In fact, some pet owners can gradually become allergic to their pets over time.

Dr. Mehdizadeh explained to MNT:

“Once the immune system is primed or sensitized to an allergen, for instance, a pet, an individual remains allergic if they are exposed to high amounts of pet hair or dander. The idea of immunotherapy or ‘allergy shots’ and desensitization only work under the guidance of an allergist, and when exposed to an allergen in small and gradually increasing amounts.”

A related point, outlined by the authors of a paperTrusted Source on pet allergies, is that “early introduction of pets at home may reduce the likelihood of developing” an allergy in the first place. In other words, if pets are brought into a home when children are young, they may be less likelyTrusted Source to develop allergies to those animals as they age.

10. Allergies aren’t serious

Thankfully, for many people, allergies are uncomfortable and inconvenient but not dangerous. However, for some individuals, an allergic reaction can culminate in anaphylaxis.

Anaphylaxis is a severe and, in some cases, life threatening allergic reaction. During this event, a large amount of histamine is released into the body, causing an inflammatory response.

Symptoms can include difficulty breathing, wheezing, stomach pain and cramps, diarrhea, anxiety, swelling of the feet, hands, lips, eyes, and sometimes the genitals, and loss of consciousness.

Even allergies that might be considered relatively minor, such as seasonal allergies, can cause significant issues. Hay fever can result in reduced quality sleep and, therefore, daytime sleepiness. In turn, this can make it more difficult to focus at work, increasing the risk of absenteeism or workplace accidents.

One 2012 studyTrusted Source investigated the impact of hay fever on the “health-related quality of life” of 616 participants. They concluded that hay fever “impairs work productivity in a greater magnitude” than hypertension and type 2 diabetes.

Another studyTrusted Source from 2009 investigated the broader effects of seasonal allergy, concluding that hay fever “has a significant negative impact on sexual function and can result in sleep disturbances and fatigue.”

11. Flowers cause hay fever

Perhaps surprisingly, this is a myth. Hay fever, or allergic rhinitis, is caused by airborne pollen. Flowers tend to produce large, sticky pollen, which does not fly through the air easily — flowers are designed to attract insects and fasten pollen to their bodies rather than release it into the air.

The major causes of hay fever are lighter pollen from grasses and trees.

Summary

Allergies are surprisingly common, and they vary from relatively minor to life threatening. It may be because of this prevalence and variety that so many myths are associated with them. Their counterintuitive nature might also play a part — after all, why should one’s immune system react to a peanut or a pooch?

Although there is still no cure for allergies, scientists continue their voyage of discovery. One day, they will surely find a way to blunt their impact on the world’s populations.

Source - Medical News Today

Microbiome research: Introducing the archaeome

 

• The human microbiome includes bacteria, viruses, fungi, and archaea. Most research has focused on bacteria, while little is known about archaea.
• Although archaea make up just 1.2% of the gut microbiome, they may have important regulatory effects.
• A recent paper outlines the first thorough description of the human archaeome, providing important new information about how these organisms might function and interact.

The microorganisms living in our gastrointestinal tracts are collectively called the gut microbiome, and they have a complex relationship with the human body.

They take energy from our food, break down certain compounds, and release important metabolites, a product of the body’s metabolism.

A change in the healthy balance of these organisms is associated with a range of health problems. These include metabolic disordersTrusted Source, inflammatory and auto-immune diseasesTrusted Source, neurological conditionsTrusted Source, and cancerTrusted Source, among others.

The human microbiome consists of bacteria, archaea, fungi, and viruses. The vast majority of research into the microbiome deals with bacteria.

More recently, the number of studies targeting fungi and viruses in the human microbiome has increased, but relatively little is known about the populations of archaea — collectively called the “archaeome.”

A group of scientists recently analyzed a large dataset of human gut microbiome samples and profiled the archaea that were present. The team’s intriguing findings appear in the journal Nature MicrobiologyTrusted Source.

The results provide more information about our resident archaea and will help researchers discover more about their impact on human health.

Lead authors Dr. Cynthia Maria Chibani, at the University of Kiel, in Germany, and Dr. Alexander Manhert, at the Medical University of Graz, in Austria, spoke with Medical News Today.

They said they were surprised to find so many types of archaea that were new to science — three genera, 15 species, and 52 strains.

“Archaea were usually neglected and understudied because a large number of archaeal species require specialized methods for cell lysis and DNA extraction, and other methodological pitfalls,” they explained.

What are archaea?

Archaea are single-celled organisms that are similar to bacteria, though they have different characteristics.

They can be spherical, rod-shaped, spiral, or rectangular. Beyond the human body, archaea live in extreme habitats. They can survive in very high and low temperatures, as well as in high-pressure, very salty, and very acidic environments.

Although archaea only account for about 1.2% of the entire gut microbiome, scientists believe that they may have considerable regulatory effects in the body.

Discovering new species

The researchers, who are also based at institutions in the United Kingdom and France, gathered data from publicly available genomes.

Their data included samples from people in 24 countries, with a range of demographic characteristics. They included other recent collections of microbiome genomes, as well, from the Unified Human Gastrointestinal Genome collection, National Center for Biotechnology Information, Pathosystems Resource Integration Center, and Integrated Microbial Genomes and Microbiomes.

The results of the analysis showed that the observed percentage of archaea present in the microbiomes was around 1.2%, which corresponds with previous research.

The team determined that most people seem to host populations of archaea that are similar. The species present seem to depend on external factors, such as geography, sex, age, and health status.

The researchers found 1,167 archaeal genomes. These included members of the orders Methanobacteriales (87.15%), Methanomassiliicoccales (12.43%), Methanomicrobiales (0.26%), and Halobacteriales (0.17%).

Next steps

The team hopes that its catalogue might serve as a unique source for future research.

Going forward, scientists might, for example, compare wild archaea with those in humans and animals. They may also investigate how archaea interact with the bacteriome and virome, as well as how the archaeome interacts with its human host.

Dr. Chibani and Dr. Manhert explained to MNT:

“We need more dedicated studies in the human archaeome field. This study was the result of looking into standard bacterial-focused studies. Hence, it will be critical to address the peculiarities of archaea.”

They said that future work should focus on “populations with a traditional lifestyle and a non-Westernized diet” because these groups “often harbor a higher diversity of methanogens in their guts.” Methanogens produce methane and increase the efficiency of digestion.

“We are just beginning to understand the actual biology of archaea in the gastrointestinal tract — how they colonize the gut [and] how they interact with bacteria, viruses, and other members of the microbiome, as well as the human host, its cells, and the gut-brain axis. So we have a lot of new territory to explore.”

In their paper, they also suggest that a previously identified species — Methanobrevibacter smithii — should be reclassified as two branches, with one represented by the previously undescribed Candidatus Methanobrevibacter intestini.

Interestingly, the analysis also uncovered 94 viruses that infect archaea.

Ákos Kovács, a professor of bacterial physiology and genetics at the Technical University of Denmark, told MNT:

“This is a fascinating study that extends our knowledge on microbes in the human gut outside of the mostly studied eubacterial kingdom. While archaea are less studied, these microbes have a nonetheless crucial role in the world’s ecosystem, as well as in human health.”

 Noting limitations

The researchers explain that because the data is based on samples that were processed to analyze the bacterial component of the microbiome, many archaeal species might have been missing from their analysis. These species may require specialized methods of extraction.

They add that an analysis of stool samples might not represent the complete diversity of species present in the intestines. This is because, for instance, some archaea form biofilms that stick to tissues and may not be present in stool samples.

Source - Medical News Today