Posts by Dr. John W. Phelts, D.C.

Enhance Injury Repair With Horsetail

At his New York, NY Office, Dr. John Phelts, D.C. sees many people with injuries, that he successfully helps them to recover from.  He attributes his high success rate in part to recommended the best supplements to help with the healing and repair process.  On of the herbs he prescribes is Horsetail.

Horsetail (Equisetum arvense) is a flowerless plant that contains 5-8% silica and silicon acids. The body uses silica in the production and repair of connective tissue and helps accelerate the healing of broken bones. Silica is also necessary to maintain and repair the nails, hair, skin, eyes and cell walls. You will often find it as an ingredient in hair and skin care products and nutritional supplements. Silica is more abundant in our tissues when we are younger, but declines with age.  

Horsetail is available as a dried herb, often prepared in capsule or infusion form, as well as a liquid extract and tincture. It requires storage in sealed containers away from sunlight and heat. Horsetail contains traces of nicotine and is not recommended for young children. In addition to the Equistetum arvense type of Horsetail, there is another species called Equisetum palustre that is poisonous to horses. To be safe, you should never take that form of horsetail.  We only carry the safest and most potent brands of herbs.

There there are many other medicinal uses for horsetail -- each with unique dosing based on the condition being treated and other individual variables. To ensure the potency and quality of the herb for your health needs, talk with Dr. Phelts.  Call 212-286-2012 and we will be happy to set you up with a consultation.



Anti Inflammatory Tea For Your Joints & Muscles


Flexibili-Tea is an aromatic infusion of herbs known to support the health of muscles, bones and connective tissues. In the recipe below we use three herbs.

First, Nettle Leaf, which has a mellow, green tea type flavor that is both nourishing and invigorating. It's rich in calcium, iron, protein and antioxidants. Second, Horsetail adds robust body to the infusion, similar to what you might find with a strong green or black tea. Rich in soluble silica, and readily absorbed by the body, Horsetail supports the regeneration of bones, cartilage and other connective tissue while improving circulation to the extremities. Finally, we use Marshmallow, which has an earthy flavor. This herb contains an abundance of mucilage, which soothes inflamed tissues and accelerates the healing of our tissues.

If you can't locate these herbs loose at a quality health food shop, buy individual tea bags and boil them together. To sweeten the tea, use stevia or try dried organic coconut crystals.


  • 20g Horsetail, Equisetum arvense
  • 20g Nettle leaf, Urtica dioica
  • 20g Marshmallow leaf, Althea officinalis


Cover in 1 pint/600ml boiling water. Strain after 15 minutes. Drink throughout day.



Water For Injury Recovery

Water is necessary for optimal injury repair.  Many people who suffer from chronic injuries are not consuming enough water.  Dr John W Phelts, D.C. performs a check to see if his patients are consuming enough water. Keep reading to learn the importance of water as it relates to your health.

Athletic or not, we all need water. And plenty of it. Hydration affects how our body works in daily activities, how prone it is to injury, and how well it recovers from injury.

"The Lord is my shepherd; I shall not want.  He makes me lie down in green pastures.  He leads me beside still waters.  " Psalm 23: 1-2

Water facilitates hundreds of critical functions in the body, many of which are essential for maintaining good muscle tone, joint mobility, and even managing pain. Specific to the musculoskeletal system, water helps:

  • transport nutrients and oxygen in the bloodstream (which muscles need to properly contract and recover).
  • flush out waste and toxins (which plays a role in reducing muscle soreness).
  • lubricate and reduce friction in the joints (which is improtant for preventing and managing arthritis).
  • facilitate muscle contraction.

Dehydrated muscles and joints are prone to:

  • Cramps: resulting from imbalances in the electrolytes needed for muscle contraction.
  • Cartilage wear and tear: joints aren't receiving nutrients needed for maintenance and repair after injury.  
  • Friction in the joints: dehydration can deprive your cartilage of the water it needs to maintain cushion, which can lead to achy or "creaking" joints and osteoarthritis (OA).
  • Pain: dehydrated muscle tissue can't flush out waste products or toxins that build up from exertion, injury or other stress.

Are You Dehydrated?

Dehydration means your body lacks the water required to function. You can become dehydrated if you don't replace fluids lost through exercise, from exposure to the elements, or from vomiting/diarrhea. Excessive caffeine consumption leads to dehydration.

Your daily water requirement depends on age, gender, activity level, body composition, health status, and climate. The color of your urine isn't an accurate guide since certain foods, supplements, and medications change urine color. To ensure sufficient water intake, drink one quart for every 50 lbs of body weight. Example: If you weigh 150 pounds, drink 3 quarts of water each day.  If you consume caffeine regularly, your requirements may be a little higher.

Dehydration can quickly become a life-threatening emergency. Signs include:

Mild Dehydration: dry mouth, irritability, headaches and muscle cramps.

Moderate Dehydration: dizziness, clumsy, exhausted, racing heartbeat. You may be unable to urinate, stand, or focus your eyes.

Severe Dehydration: the function of vital organs is impaired. Without water, you will enter a coma and die.

Put Down those Sugary Sports Drinks. Here are Sweeter Ways to Get Hydrated

  • Coconut. Coconut water is rich in natural electrolytes. While not scientifically proven, theoretically it can boost hydration and you may enjoy the flavor more than plain water.
  • Infuse It! Add fresh or frozen slices of orange, lemon, or lime to your water. Try frozen berries or melon; also try cucumber, mint, ginger or parsley.
  • Teal. Iced or hot, caffeine-free and herbal teas count toward your water intake and support healthy hydration.  Try sweetening with stevia.
  • Fruit & Veggies.  Many fruits and veggies have a high water and nutrient content: cantaloupe, honeydew, strawberries, watermelon, pineapple, peaches, cucumber, lettuce and celery.

Dr. Phelts does a simple non-invasive applied kinesiology (AK) test to see if you are consuming enough water.  There are also factors that can be seen in blood work that may indicate dehydration.  Give us a call 212-286-2012 for a health check, which includes testing for dehydration.  We are located in Manattan, two blocks from Grand Central station and four blocks from Bryant Park.  We serve the 10016 and 10017 zip codes.



Low Back Pain and the SI Joint

We treat a large number of people with back pain in our New York office, and Dr. Phelts finds that quite a few cases of back pain stem from the sacroiliac (SI) joint. Research has revealed that about 25% of all back pain originates in the SI joint, and now new research confirms what we have noticed in our office: chiropractic is an effective approach to treating this problem.

Research Proves Chiropractic Treatment Helps Increase Movement in the SI Joint

In the study published in the Journal of Bodywork and Movement Therapies, 32 women with sacroiliac joint syndrome were split into two groups and asked to take part in one of two treatment therapies. one group received a chiropractic adjustment only at the sacroiliac joint, and the alternate group received an adjustment to the sacroiliac joint and the lumbar spine.

Researchers found significantly more improvements in both pain and movement immediately following treatment, two days later, and 30 days later for the group who had been given high-velocity low-amplitude manipulation to both the sacroiliac joint and the lumbar spine. This asserts that chiropractic therapy applied to these two areas offers both short term and continuing benefits for sacroiliac joint pain sufferers—even with just a single treatment round.

So, if you are having trouble with sacroiliac joint pain, or cope with back and leg pain and want to see if your sacroiliac joint is the root, a consultation at our New York office may be the first—and best—step towards feeling better. Give our office a call today at (212) 286-2012.  We are conveniently located in the heart of Manhattan, just two blocks from Grand Central Terminal.

Kamali F, Shokri E. The effect of two manipulative therapy techniques and their outcome in patients with sacroiliac joint syndrome. Journal of Bodywork and Movement Therapies 2012;16(1):29-35.


Move Often- It May Extend Your Life.

There is mounting evidence of the ill-effects associated with sitting too much, movement has become essential for living well.  Movements helps maintain healthy joints, muscles, bones, and organs.  Dr. John W. Phelts DC practices in the heart of Manhattan, which means that he sees many patients, whose occupation requires prolonged sittling.

The way your body moves (functions) is in direct relation to its form (structure) and vice versa. To get a better understanding of this relationship, let's talk cars...

Imagine your are driving an brand new Porsche. You can dip and weave in and out of traffic with ease. This car handles turns better than a rollercoaster. It adrenaline rushing acceleration and can stop on a dime. But if you don't perform routine maintenance, all that beautiful form is for nothing and your Porsche no longer functions well. Form determines function and how well you care for function affects form. Now, back to your body…

Our body's God given innate intelligence creates movement patterns that are in dynamic play between form and function, influenced by the type of care we give our body. This complex interaction includes the skeleton, connective tissues like ligaments and tendons, muscles, joints, our breathing, heart function and posture.  Mounds of research indicate that chiropractic adjustments improve the strength and inergrity of ligaments, while preventing osteoarthritis of the spine. 

Sitting is Killing Us

Today's society is plagued by sitting activities.  On average americans sit about 14 hours a day: at meals, in traffic, at school or work, in front of electronic devices and TVs. Prolonged sitting can increase our risk for obesity, diabetes, heart disease, and cancer. It's a primary culprit in these health problems, which shorten life expectancy:

Chronic back, hip and neck pain: related to weakened core muscles and shortened ligaments connecting the hips, pelvis, and spine.

Shallow breathing (reduced respiratory capacity): related to compression of the respiratory muscles while sitting and tightness in the accessory muscles around the rib cage, shoulders and neck.

Gastrointestinal issues and indigestion: related to reduced circulation to the gut.

Low energy level, depressed mood: related to lack of engagement of systems that produce hormones and other substances that elevate mood.

But, I go to the gym...

Even if you exercise at a gym, or fitness walk for an hour each day, you're still sitting too much for that one hour to make a real difference. Leisurely, periodic movement is critical to lowering your risk for chronic health problems and even early death. Some ideas:

Every 30 minutes, stand/walk for about 10 minutes.
Stand while talking on the phone, using a device, or watching television.
Desk worker: Try a standing desk or improvise with a high table or counter; invest in a specialized treadmill desk.
Walk with colleagues for meetings instead of sitting in a conference room.
Once an hour, stand and breathe deeply for five minutes.
Strengthen and stretch with standing yoga poses.
Try apps designed to remind you to move and stretch during work hours.
Get adjusted by your chiropractor two to three times a month.
Enjoy the benefits of getting up and moving, which include . . .

Burning additional calories, which can lead to weight loss and increased energy.
Better digestion, the result of light movement after meals.
Support for the respiratory system's role in helping the body remove waste and toxins; movement gives the muscles "room to breathe" placing less stress on joints, muscle and ligaments.

If you have chronic pain or other problems associated with too much sitting, make an appointment with Dr. Phelts at his mid-town office for a thorough postural and biomechanical assessment. 212-286-2012.  He is located in the 10016 zip code.

References: "What are the Risks of Sitting too Much?" posted by Laskowski, E.R. (May 2018)

IowaChiroClinic. Org "Does Posture Really Affect Breathing?" Accessed April 8 2019: "Breathe Deeper to Improve Health & Posture" posted by Marcin, J. (posted 27 Feb 2018)

CNN. "Yes, sitting too long can kill you, even if you exercise." Posted by Scutti, S.(Posted on 12 Sept 2017)


Fatty Liver Disease- More Than An Alcohol Disease

Fatly liver disease is defined as an excess accumulation of fats in your liver.  The most common cause of this condition is alcohol consumption.  However, you can develop this disease even if you do not consume alcohol.  It is known as non-alcoholic fatty liver disease or NAFLD.  NAFLD is frequently seen in diabetics, obesity, and those who have high cholesterol and triglycerides.

Fatty liver is a silent disease, meaning there are usually no symptoms until other complications arise as a result.  Eventually when symptoms do appear, they can be non-specific like, fatigue, swelling in the abdomen and legs, and mental confusion.  NAFLD can cause inflammation of the liver, steatohepatitis, liver failure, and liver cancer. This is why it is important to have your blood tested regularly.  Tests like SGOT, SGPT, GGT, and Uric acid can tell us if there may be an issue with the liver, before complications develop.

Dr. John W Phelts, D.C. believes the best most effective medicine is prevention.  According to the American Liver Foundation, adopting a nutrient dense diet and cardiovascular exercise can help prevent the development of NAFLD and potentially reversing the problem in its early stages.  Reducing consumption of fructose will also help.

So what causes NAFLD?
One of the Leading Causes of Non-Alcoholic Fatty Liver Disease is Fructose.  Fructose is a type of sugar found in fruit and fruit juice, high fructose corn syrup, honey and even agave syrup.  FYI- agave syrup contains more fructose than high fructose corn syrup.   

Dr. Robert Lustig from the University of California, researched fructose metabolism extensively.  His research was published in the Journal of the Academy of Nutrition and Dietetics,  where he calls fructose a “chronic, dose-dependent liver toxin.” In it he explains that ethanol (an alcohol) is a by product of fructose fermentation. The paper revealed certain similarities between alcohol and fructose metabolism:

1. The liver’s metabolism of fructose is similar to alcohol, as they both serves as substances for converting dietary carbohydrates into fat, thus promoting insulin resistance, abnormal fat levels in the bloodstream, and fatty liver.
2. Fructose undergoes a specific reaction with proteins, leading to the formation of superoxide free radicals which can result in liver inflammation similar to acetaldehyde, an intermediary metabolite of ethanol (alcohol).
3. By stimulating a particular pathway of the brain both directly and indirectly fructose creates a habituation and possible dependence, much like that of alcohol.

How can supplements and blood testing help this condition?
According to one study done on mice, vitamin E deficiency was linked to liver inflammation and injury.  When the mice were supplemented with full spectrum vitamin E, there was significant symptom relief and improvements in triglycerides, lipid peroxides, liver markers, and decreased liver scarring.  The study also showed that non-full spectrum Vitamin E supplementation yielded inferior results compared to full spectrum. Wheat germ oil contains full spectrum vitamin E.

Because fatty liver disease is silent, Dr. John Phelts includes liver enzymes are part of his standard blood panel that he orders for his patients.  This allows him to see if his patients may be moving towards the development of this condition, so that we can take measures to prevent it form ever occurring.  If the conation is more advanced, then there are measures that we can take to improve or reverse the condition naturally.

Supplementation with Vitamin E and other liver support formulas may be all that is necessary to keep this condition at bay but you won’t know what you need until you get tested.

Make sure to get your blood tested first to make sure you are on the right supplement and nutrition program. By getting a comprehensive blood panel and tissue mineral profile analyzed  by Dr. Phelts, an individualized program can be compiled for you to prepare you for your new healthy lifestyle.  That way you won’t have to guess what you may need to eat or what supplements that you should be taking.  You can take the guesswork out by getting tested objectively.  Don’t wait, stop by or call our office today 212-286-2012!  We are located near the 10016, 10017, and 10018 zip codes near grand central station.

1, 2.  American Liver Foundation, NAFLD  
3. Journal of the American Dietetic Association, September 2010, Volume 110, Issue 9 Pages 1307-1321
4.  Study presented at the annual meeting of the American Society for Biochemistry and Molecular    Biology


Eye Exercises for Vision

The concept that certain eye movement patterns can correct vision abnormalities such as near- or farsightedness has been around since the 1920s. While there's no scientific evidence to support these claims, helath care professionals do realize that exercising the eyes does have health benefits.  Dr. John W Phelts, D.C. sees many patients who have vision problems and has seen great improvements.  In his New York, NY office he uses applied kinesiology and blood testing to determine which protocols will help improve patients with vision issues.

Did you know that your eyes are supported by muscles called extraocular nuscles?  They make it possible to look in various directions, like up and down, left and reight.  Exercising these muscles may improve your vision and eye health.  Strong eye muscles also protect against the negative effects of vision overuse patterns, such as digital eye strain or frequent night driving.

Below are two eye exercises; the first is for general eye health and the other is for glaucoma.

Figure Eight Eye Exercise

You may have practiced this exercise, sometimes called "yoga eyes," if you've ever taken a yoga class. This exercise should be done from a seated position, such as at your desk, while relaxing in your favorite chair, or in an easy, seated yoga pose.

Pick a point on the floor about 10 feet in front of you and focus on it.
Trace an imaginary figure eight with your eyes.
Keep tracing for 30 seconds, then switch directions.

Exercise to Reduce Intraocular Pressure Related to Glaucoma

Perform either option A or option B in combination with the blinking technique, performed simultaneously. These can be done with or without wearing your glasses.

A. Alternate between looking at very distant and very close objects. For example, when seated or standing, alternate between looking at your thumb, then looking at an object that is farther away, such as a building or a tree. Do this exercise for 40 seconds.

B. Keeping your head stationery, alternate between looking right and left with your eyeballs for 1 minute.

Blinking Technique. Very light and fast blinking, the eyelids are light as "butterfly wings".

While not all vision abnormalities or medical conditions can be corrected by eye exercises, keeping the eye muscles strong, flexible, and nourished is essential to protecting eye health.  

There are amino acids and b-vitamins that can also improve vision.  Dr. John Phelts uses Applied Kinesiology (AK) testing to determine the proper balance of these nutrients for improved vision. He also uses an AK techmique to reduce eye pressure in patients with glaucoma.  If you are interested in improving your health with natural methods then give us a call 212-286-2012.  We are located just two blocks from Grand Central station.  We are near the 10016, 10017, and 10018 zip codes.  



Bilberry Goodness

Historically bilberry leaves and fruit have been used for managing diabetic concerns, gastrointestinal complaints, eye health, and urinary system infections. Extracts of bilberry are used to address age-related degeneration in the circulatory systems and diseases where inflammation is a strong underlying factor, such as heart disease and retinopathy (eye problems). There's also evidence that bilberry may help alleviate eye fatigue caused by extensive computer and video monitor use.

Bilberry fruit contains potent antioxidant and anti-inflammatory properties. These are bleieved to come from the fruit's anthocyanoside (aka anthocyanidins). These plant chemicals are powerful antioxidants and may help protect the body from the damaging effects of inflammation and oxidative stress.

Adding bilberry to your daily diet is a delicious way to enjoy its health protective benefits: You can incorporate bilberries into your diet by adding it to your yogurt, oatmeal, or salad.  For specific health concerns, extracts of bilberry are available in capsule and tincture, both of which should be standardized to contain a specific percent of anthocyanins. Check with your Dr. John W. Phelts, D.C. for the appropriate extract for your helath needs.


Chu W, Cheung SCM, Lau RAW, et al. Bilberry (Vaccinium myrtillus L.) In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition.(2011). Chapter 4. Boca Raton (FL): CRC Press/Taylor & Francis. Accessed 10 Aug 2017 from:

Ozawa Y, Kawashima M, Inoue S, et al. Bilberry extract supplementation for preventing eye fatigue in video display terminal workers. J Nutr Health Aging.(2015) May 19(5):548-54.


Computer Screens and Eye Strain

We're in a new age of technology and connectivity, and with it comes new health concerns. More than ever, our eyes are in front of screens - from smart devices and computer monitors to televisions and movie screens. And, more than ever, people of all ages are complaining of eye fatigue, headaches, blurry vision, dry eye, and twitching of the eye or eyelid. This is often referred to as Computer Vision Syndrome (CVS).

Every part of our eye is vital to healthy vision - from the tear ducts to the cornea to the various nerves and muscles. And every part of our eye is affected by our habits, including the stress and strain placed upon them from using digital devices, whether at school, work or home. While research in this area is still new, current studies show that the blue light emitted from cell phone screens and similar devices causes damage to retinal cells. Scientists believe the damage stems from the higher energy level in the shorter wavelength of blue light, hitting the eye with greater intensity than other light sources.  

Dr. John W Phelts, DC sees many people who have CVS symptoms in his New York, NY office.  He uses meridian therapy, applied kinesiology (AK), nutrition, and chiropractic to address these issues.  Although his treatments are effective and results are often immediate, if the root cause is not eliminated or minimized, then the symptoms may return.  For some individulas this may be difficult, because their livelihood may require that they are in front of screens all day.  If this is you, see the recommendations below to reduce CVS.   

Reduce Eye Strain While Using Digital Devices
Serious vision problems don't necessarily happen all at once; they can creep up on us over time if we're not careful. That's why early - and daily - intervention is critical. The following strategies can help minimize eye strain and prevent CVS from becoming a problem for you now and in the future.

Position your desktop computer screen 20 to 26 inches away from your eyes and a little bit below eye level.

Hold smaller devices 12-15 inches from the eyes.

Choose screens that can tilt and swivel. Use a device holder for smaller devices.

Use the appropriate screen display for your computer; change displays between light and dark mode; invest in a high-quality monitor.

Use a blue-light / glare filter over your computer screen or your glasses.

Place a document holder next to your screen. It should be close enough to allow you to comfortably glance back and forth to the screen and document.

Use soft lighting at your work space to reduce glare and harsh reflections.

Take a 20 second break every 20 minutes. Look at objects in the distance, such as a picture on a far wall, a building outside, or a tree, for example. Blink often and exercise your eyes 

If you're concerned about changes in your vision or have experienced the symptoms of CVS, speak to Dr. Phelts about additional health steps you can take.  Their are reflex points on your body that you can stimulate to help deal witht he stress of CVS.  We are located just two blocks from Grand Central station.  We are near the 10016, 10017, and 10018 zip codes.  Give us a call 212-286-2012.


American Optometric Association, "Glossary of common eye and vision conditions."

"Computer Vision Syndrome"

Boptom, SJ, Asper, L, et al., "Ocular And Visual Discomfort Associated With Smartphones, Tablets And Computers: What We Do And Do Not Know." Clin & Exper Optometry. (Jan 2019)

Blehm, C, Visnu, S. et al. "Computer Vision Syndrome: A Review" Surv Ophthalmol. (2005) May-Jun; 50(3):253-62. "Blue Light from Your Phone May be Permanently Damaging Your Eyes." "Eye Damage Risk From Cellphones, Laptop Screens Revealed." By Spear, Lisa. Posted 11 Aug 2018. Accessed 6 Mar 2019:


Important Thing To Know About Vitamin A.

At Phelts Chiropractic PC in New York, NY, we recommend only the most effective supplements to our patients.  We often see signs of Vitamin A defieciency on the laboratory tests we order.  it is improtant to have a professional practitioner like Dr. John W Phelts DC analyze your results to make sure you get the correct form of Vitamin A for you, as you will see why below.  Even if another health practitioner ordered the labs, Dr. Phelts is willing to analyze the results as a second opinion.  Let's find out why Vitamin A is so important for your health.

Part of a family of substances called retinols, Vitamin A is important to our overall health and, specifically, our skin, immune system, and eyes.  Retimol is the form of Vaitamin A that our bodies can readily use.

There are primarily two sources of vitamin A.  One is from animals and the other plants.  Animal sources include eggs and organ meats like liver and kidney.  They contain retinol, which has a high bioavailability.  Plant sources contain carotenoids which are called pre-vitamin A, because they must be converted in the small intestine to retinol.  The body only converts 10% -12% of carotenoids to retinol, so they are not the best source.  The carotenoids that are not converted benefit us by acting as anioxidants in our bodies.  Our daily diet should include a mix of plant and animal-based foods.  

The following foods provide Vitamin A in its most readily available form; they are listed in each category according to their highest level of readily absorbable Vitamin A content. (This is not a complete list)

Meat and Fish
Beef Liver
Cod Liver Oil
King Mackerel

Sweet Potato
Winter Squash
Turnip Greens
Sweet Red Pepper


Goat Cheese
Roquefort Cheese

The daily recommendation of Vitamin A for children changes from birth through age 18, so it's best to check with Dr. Phelts before giving Vitamin A to a child. 

Even if you're eating a variety of organic, whole foods, it's possible you're not getting enough Vitamin A. Conditions of the digestive track including Chron's, gallbladdr and liver conditions, pancreatic enzyme deficiency, and cystic fibrosis, can impair the conversion.  Some people may have a genetic factor that doesn't allow them to convert Vitamin A. This is why some people have signs of Vitamin A deficeincy even though they are consuming plenty of orange and yellow friuts and vegetable.  Vitamin A deficiency that may show up as health conditions of the eyes, skin, or immune function.  

Vitamin A supplements are widely available but the purity and consistency of the supplement can vary. Some supplements will contain preformed Vitamin A; some will have beta carotenes, and some will contain a combination. Dosing Vitamin A is highly individualized and because it is a fat-soluble vitamin, it can accumulate to toxic levels in the body. Women who are of childbearing age or pregnant should be under a physician's care if taking Vitamin A. As always, speak to Dr. Phelts about the best form and dose of a Vitamin A supplement for your needs.

If you would like an analysis of your blood work and an alternative method of improving your health, give us a call (212-286-2012).  We use Science Based Nutrition and  Applied Kinesiology (AK) to put you on the road to health.  We are located two blocks from Grand Central station in the Murray Hill section of Manhattan near the 10016, 10017, and 10018 zip codes.  We also do consultations by phone.


Rasmussen HM, Johnson EJ. Nutrients for the aging eye. Clin Interv Aging. (2013) 8:741-8.

Vitamin A Fact Sheet For Health Professionals:

The Journal of Nutrition, Volume 142, Issue 1, 1 January 2012, Pages 161S–165S, "20 Foods that are High in Vitamin A"