Common Symptoms and Causes of Vitamin A Deficiency
Vitamin A is another name for retinoids, chemical compounds used by our bodies for certain essential physiological functions. The classification “vitamin A” also encompasses organic pigments called carotenoids that are converted into retinoids by the body. Retinoids are considered preformed vitamin A, and convertible carotenoids (like the most well-known, beta-carotene) are referred to as provitamin A.
The effects and symptoms of vitamin A deficiency most frequently manifest in four areas of our health: the eyes, skin, hair, and immune system. Beyond these areas, vitamin A deficiency can result in less-localized and more generic symptoms such as fatigue, insomnia, loss of appetite, weight loss, dry mouth and nasal passages, and brittle nails.
Insufficient vitamin A intake, absorption, or use presents the most danger to our eyes. Likely symptoms include dry or inflamed eyes and diminished vision, particularly at night or in dimly-lit atmospheres. Prolonged vitamin A deficiency can lead to “night blindness,” the inability to see at all in these conditions. Retinoids ensure adequate levels of rhodopsin, a pigment in the retina responsible for the eye’s ability to sense dim light.
Symptoms of vitamin A deficiency will often manifest as worsening epidermal health. Dry and rough skin, increased acne, and premature wrinkles may all be signs of too little vitamin A. Another common symptom is a condition called hyperkeratosis. Hyperkeratosis can present in a number of ways (corns and calluses are both forms of the condition), but when it stems from a lack of vitamin A, it appears as goose-bump texturing, usually on the forearm and thighs at first. This is a result of the over-production of keratin, a skin protein that obstructs hair follicles.
The health of our hair can also suffer from a vitamin A deficiency. Symptoms can include dry, dull, or stringy hair, as well as dandruff. Ongoing vitamin A deficiency can even lead to hair loss. Hair loss can occur over the whole body in cases where hyperkeratosis spreads.
Vitamin A deficiency can take a serious toll on our immune system. While vitamin C is widely perceived to be the most important for optimal immune system functioning, actual scientific evidence shows that vitamin A plays a far greater role in this aspect of our health. It is essential to tissue maintenance, mucous membrane operations (the immune system’s first line of defense), and it boosts white blood cell performance. Vitamin A deficiency leads to greatly-increased susceptibility to viral infections. In particular, respiratory and urinary tract infections can occur frequently in people with inadequate levels of vitamin A.
The most common cause of vitamin A deficiencies is insufficient dietary intake. Vitamins are not naturally produced by our bodies, so must be obtained from external sources. Preformed vitamin A—retinoids—are only obtainable from animal-derived foods. Beef, poultry, and fish livers are the most vitamin A-rich foods. Egg yolks are another key source of vitamin A, as are milk and other dairy products like cheese, butter, and yogurt.
Carotenoids, or provitamin A, are readily available from many plant sources to be converted into retinoids. Carrots, for which carotene is named, is the richest vegetable source of provitamin A. Dark, leafy greens such as spinach, kale, swiss chard, and turnip, mustard, and collard greens are also excellent sources. Broccoli, asparagus, red bell peppers, sweet potatoes, summer and winter squash, tomatoes, apricots, cantaloupe, and watermelon are other good options for obtaining provitamin A. Some herbs, particularly parsley, basil, and oregano, provide carotenoids as well.
The liver is responsible for converting carotenoids into retinoids, and for storing vitamin A. Therefore, liver disease and disorders can be at the root of vitamin A deficiencies.
Other nutritional deficiencies can also cause vitamin A deficiencies. Vitamin A is fat-soluble, so deficiencies can occur as a result of an extremely low-fat diet. Protein and zinc are both necessary for the use and absorption of vitamin A, so diets lacking enough of either can deprive the body of the nutrient.
Just as too little dietary fat can lead to vitamin A deficiencies, the same is true of medical conditions that hinder the body’s absorption of dietary fat. Such conditions can include a variety of diseases, intestinal parasites, and chronic diarrhea (which has an extensive list of possible causes itself).
Some medications have been linked to vitamin A deficiencies. The clearest ties have been established with drugs for lowering cholesterol. These include pharmaceuticals categorized as HMG-CoA Reductase Inhibitors (such as Lipitor and Zocor) and Bile Acid Sequestrants (like Cholestyramine).
While these are the most common symptoms and causes of vitamin A deficiencies, this article is not exhaustive, nor is anything herein necessarily indicative of a vitamin A deficiency. This article is solely for informative purposes. Only a doctor can diagnose, determine a cause of, and treat any nutritional deficiency. A well-balanced diet regularly incorporating some of the foods listed above is the single best way to prevent a vitamin A deficiency.