In the sixth grade, we spent a large portion of health class talking about nutrition. We learned about the food pyramid, cholesterol, and the mechanics of the digestive system. We also spent an inordinate amount of time discussing nutrition-related diseases like rickets, scurvy, and beriberi.
I’m not sure why our teachers thought that a group of well-fed children from Ohio were at risk of developing such archaic diseases of malnutrition, yet we spent more time learning about the poor dietary habits of seventeenth-century pirates than we did learning about the consequences of real-life nutritional deficiencies or about the actual nutritional benefits of vitamins.
As Americans during a time of relative plenty, we don’t have to worry about some of the most destructive forms of malnutrition, but a lopsided diet that deprives the body of vitamins and minerals can still take a big toll on our health.
It’s not true that eating carrots can make your eyesight better, but not ingesting vitamin A can have disastrous consequences. Also called retinol, it’s required to produce a photoreceptor pigment in the retina, as well as maintain skin health. Due to a rice-based diet, vitamin A deficiency is still rampant in Asia, where it’s the most common cause of childhood blindness. In adults, it cripples the immune system, causes skin problems, and destroys the eyes. The first symptom is usually night blindness, followed by the failure of the eye to lubricate itself by producing tears. Eventually, patches of dead skin and other secretions can build up on the conjunctiva, and lesions develop on the cornea.
Vitamin A deficiencies can also cause the skin to harden and crack, including the mucous membranes in the lungs, digestive system, and urinary tracts. To prevent it, eat plenty of dark, leafy-green vegetables such as spinach and kale, as well as bright-colored fruits like papayas and mangoes. Egg yolk, liver, and fish oil can also be helpful. Vitamin A is a fat-soluble vitamin, so eating it with some kind of dietary fat increases the amount of the vitamin that the liver can absorb.
The B-complex vitamins are a large group of important nutrients. Most of these vitamins, including niacin and thiamine, are nearly ubiquitous, so a deficiency is quite rare, but too little B9, also called folate or folic acid, can cause anemia, weight loss, weakness, heart murmurs, and loss of appetite. Folate is especially important for pregnant women, as inadequate intake can result in low birth weight or spinal tube defects. Breastfeeding women and smokers should ingest large amounts of folate. Dairy is a poor source of the nutrient, but melons, strawberries, oranges, beans, and asparagus contain plenty.
A deficiency of vitamin B12, which plays a vital role in the synthesis of DNA and brain functions, is a common form of malnutrition in America. The risk if B12 deficiency increases with age, and according to the American Academy of Family Physicians, about 15 percent of adults sixty-five years and older are affected. It causes anemia, paresthesia, neuropathy in the limbs, and erosion of the spinal column. It’s also linked to memory loss, depression, dementia, and an increased risk of heart attack and stroke. Elderly people with light diets and chronic alcoholics have an increased risk for developing a B12 deficiency, as do vegans, since they don’t eat a diet rich in dairy or certain meat products that provide all the B12 a person needs.
The quintessential C deficiency is scurvy, a disease of bleeding gums that can also cause poor wound healing and anemia. A person would need to abstain for several weeks in order to deplete all reserves of this nutrient, so few people are at risk of developing a severe deficiency. The current recommended daily allowance for vitamin C is 75 mg daily for women and 90 mg for men. Pregnant or lactating women need a little more, and smokers need almost twice as much as the RDA, since the habit depletes vitamin C at a greater rate. Even without a complete deficiency, people who are low on vitamin C find that it can cause problems processing and eliminating cholesterol and can also cause the immune system to work less effectively.
In children, a deficiency of Vitamin D results in rickets, a disease of skeletal deformities. The vitamin is in charge of maintaining calcium levels in the body and aids in our bones’ absorption of calcium, so it’s important for adults, too. Some data also suggests that adequate vitamin D intake can provide protection from osteoporosis, high blood pressure, and some forms of cancer. A deficiency of the vitamin leads to bone problems like osteoporosis. People at the most risk for vitamin D deficiency are the elderly, the obese, and infants who breastfed exclusively, since breast milk is not an adequate source of the vitamin.
This vitamin has an essential role in blood clotting. Our bodies get vitamin K from our diet, including green leafy vegetables like broccoli and collard greens, and from our intestinal tract, where it’s produced by bacteria. When the body doesn’t have enough, it can result in bleeding disorders, heavy periods, nosebleeds, easy bruising, and anemia.
Salicylates are substances found in foods like nuts, fruits, spices, and mints, and they can block the absorption of vitamin K, causing a deficiency. In fact, aspirin is a salicylate, and the absorption-blocking action is how it keeps blood from coagulating. People on anti-coagulant drugs are actually cautioned to avoid foods with vitamin K, to prevent the vitamin from counteracting the medication.
A lackluster diet isn’t the only way to develop a vitamin deficiency; diseases like Crohn’s, celiac disease, cystic fibrosis, and others can prevent the absorption of vitamins in the digestive tract. Because most diets provide enough vitamins (even American diets), a serious deficiency is often a sign of one of these underlying conditions. Though most people can rest easily knowing that they’ll never experience rickets, pellagra, or tetany, vitamin deficiencies are still serious concerns with serious consequences.