Vitamin A: Top Ten Foods to Boost Immunity and Protect Vision

Vitamin A offers the body a powerhouse of protection. It is best known for its ability to enhance the immune system and protect vision. However, proper doses of Vitamin A can also help slow down the process of aging, reduce fatigue, protect against gastrointestinal disorders, assist with weight loss, and keep skin disorders such as acne and eczema at bay.

Vitamin A acts as an antioxidant and offers protection against free radicals. Without going into a chemistry lesson, free radicals are atoms that damage cells. Damaged cells can lead to a host of physical ailments including cancer, heart disease, and autoimmune diseases such as multiple sclerosis, Sjogren's syndrome, fibromyalgia, and rheumatoid arthritis.

Obtaining sufficient levels of Vitamin A is especially important for newborns and children. In addition to offering protection against colds and flu, Vitamin A is essential for optimal growth and development, as well as boosting the immune system.

According to Vitamin Angels, a non-profit organization that provides Vitamin A supplements to third-world countries, "Vitamin A is essential to immune function especially in children under five who are most vulnerable to common infections and diseases."

The best source of Vitamin A for babies is breast milk. The Rehydration Project website states, "Colostrums is three times richer in vitamin A than mature milk and contain antibodies and other protective factors which serve as the baby's first immunization."

Vitamin A deficiency is most prevalent in impoverished nations, but also occurs in developing countries. A multitude of health problems can arise when individuals do not receive adequate intake of vitamin A. Deficiencies in children typically appear as viral infections, growth retardation, bone abnormalities, and blindness.

Since Vitamin A helps the immune system, lack of vitamin A can leave children vulnerable to an increase in viral infections including pneumonia, measles, and chicken pox. Symptoms of adult vitamin A deficiency include dry skin and hair, loss of appetite, frequent bladder and kidney infections, dental decay, sinusitis, gastrointestinal ulcers, and night blindness.

Vitamin A is found in foods originating from animals such as eggs, milk and beef liver. However, fruits and vegetables that contain carotenoids are converted into vitamin A by the body.

The Linus Pauling Institute states, "carotenoids are a class of more than 600 naturally occurring pigments synthesized by plants and are the source of the yellow, orange, and red colors of many plants." Carotenoids go by many names including: alpha-carotene, beta-carotene, gamma-carotene, provitamin A, and preformed vitamin A which is also known as retinol.

Too much vitamin A can be just as harmful as inadequate levels of vitamin A; especially in infants and children. The George Mateljan Foundation has published a list of vitamin A requirements via their website at WHFoods.com. Pregnant and nursing women should monitor their intake of vitamin A to aid in the prevention of birth defects such as spina bifida and cleft palate. The National Academy of Sciences states, "Pregnant women should limit vitamin A supplementation to 5,000 IU per day."

In order for the body to fully utilize vitamin A it must be consumed with sufficient levels of protein, dietary fat and zinc. Protein can be derived from meats such as beef, poultry, and seafood; particularly cod, tuna, salmon, scallops and shrimp. Animal-based products such as milk, eggs, and cheese include high levels of vitamin A.

Vegetarians and vegans can ensure they obtain adequate levels of vitamin A by consuming certain fruits, vegetables, beans, nuts, seeds, and grains.

Top 10 Foods Rich in Vitamin A

While dozens of foods are rich in vitamin A, the following ten foods offer the highest level of this immune-boosting, anti-aging, vision protecting nutrient.

1. Butternut Squash tops the list of vitamin A rich food. This sweet, nutty flavored squash can be baked, boiled or roasted. It pairs well with roasted root vegetables such as beets, onions, carrots, and potatoes. One cup of cooked butternut squash contains nearly 23,000 I.U. of vitamin A. Serving size should be limited to one-half cup per day for healthy adults, and one-quarter cup for pregnant women and children under age 5.

2. Kale is a form of cabbage often used in combination with other types of dark green leafy vegetables which are cooked down to create a scrumptious dish known in the South as "greens." Kale contains sulforaphane which scientists claim contain anti-cancer properties. One cup of cooked kale provides over 17,000 I.U. of vitamin A. Kale is also rich in vitamin C, vitamin K, calcium and fiber.

3. Carrots have earned a reputation for maintaining eyesight and with good reason. Just one half cup of cooked carrots yields 13,286 I.U. of vitamin A. Carrots are also a good source of potassium, calcium, vitamin C, and fiber.

4. Pumpkin is primarily known for holiday pies, but this bright orange vegetable offers an abundance of vitamin A and is a good source of dietary fiber. Pumpkin is a great addition to baked vegetable medleys and brings a hint of sweetness when added with butternut squash and roasted potatoes. One cup of cooked pumpkin yields 12,230 I.U. of vitamin A and is a good source of potassium, magnesium, calcium, vitamin C, and niacin.

5. Bok Choy is a Chinese cabbage that is often referred to as Napa cabbage within the U.S. This dark green leafy vegetable is served in stir fry's and cabbage salads such as cole slaw. One cup of Bok Choy cabbage provides over 7,000 I.U. of vitamin A and a mere 20 calories.

6. Passion fruit is commonly used in energy drinks and alcoholic beverages in the U.S. Two types of passion fruit exist. One is bright yellow and can grow to the size of a grapefruit. The other is dark purple and resembles a plum in size and color. Both species are known for their high level of dietary fiber, potassium, magnesium, and calcium. One cup of this sweet-tasting fruit contains about 3,000 I.U. of vitamin A and is a good source of protein and iron.

7. Yellowfin Tuna: Also known as Ahi and Albacore, Yellowfin Tuna is one of the top ranking sources of vitamin A derived from seafood. A mere four ounces of this medium-mild flavored fish provides 2,520 I.U. of vitamin A.

8. Watermelon is a low-calorie food that provides the human body with potassium, magnesium, calcium, protein, and dietary fiber. Two cups of this sweet fruit yields over 1,600 I.U. of vitamin A. When combined with one cup of passion fruit, watermelon provides nearly half of the daily vitamin A requirement for healthy adults.

9. Goat Cheese: With similar nutrients of human breast milk, goat cheese offers a higher level of vitamin A than cheeses derived from dairy cows. Three and one-half ounces of this soft, mild-flavored cheese provides nearly 1,500 I.U. of vitamin A.

10. Cheddar Cheese: One cup of cheddar cheese provides 28 grams of protein; 815 milligrams of calcium; and 1,132 I.U. of vitamin A. Unfortunately, cheddar cheese is also high in calories and fat. One cup equals 455 calories and 37.5 grams of fat; nearly double the daily recommended amount. However, cheddar cheese is a good source of protein that can improve the absorption of vitamin A. Eating cheese in moderation can be a healthy choice.

It is important to note that certain drugs and over-the-counter remedies can interfere with vitamin A absorption. Three of the main culprits include antibiotics, cholesterol-lowering medications, and laxatives. Individuals with liver disease and hypothyroidism should consult with their doctor before taking vitamin A supplements or consuming foods with high levels of vitamin A.

Sources:
Vitamin Angels
Beating Free Radicals by Dr. Glen Gordon
Rehydration Project on Breast Milk and Vitamin A
Linus Pauling Institute Report on Carotenoids
WHFoods on Vitamin A Intake Requirements
The National Academy of Sciences
Vegetable Nutrition Chart
Fruit Nutrition Chart
Meats and Protein Nutrition Chart