It's a popular proverb: An apple a day keeps the doctor away. But what happens when, instead of that one apple, you eat 3 lbs. of the fruit? Can there be too much of a good thing?
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Sarah Krieger, a registered dietitian in St. Petersburg, Florida, and a spokeswoman for the American Dietetic Association, thinks so. She says that everything, even the nutritious foods, should be eaten in moderation.
"More of anything is not always the answer," Krieger said. "Not picking on apples, it could be anything. It could be pears."
While some foods are healthy for you, "more" does not always mean "better." Eating too much of even healthy foods can cause trouble.
Any food eaten to excess would not be recommended. That's why we recommend people eat a balanced food plan that includes a variety of foods.
Joanne Larsen, registered dietitian and operator of the Ask The Dietician website
An Embarrassment of Riches
Apples, rich in vitamins, also contain fiber. But consuming too much dietary fiber can adversely affect your health, says Lona Sandon, an assistant professor in the Department of Clinical Nutrition at the University of Texas Southwestern Medical Center.
The American Dietetic Association recommends that adults consume about 25 to 35 g of fiber daily, or about 5 cups of fruits or vegetables a day. Sandon cautions that eating far beyond that can prevent the body from absorbing certain valuable minerals, such as iron, zinc, calcium, magnesium and phosphorus.
Because dietary fiber -- plant material found in fruits, vegetables and grains -- is resistant to digestion in the human gastrointestinal tract, it has both advantages and disadvantages.
Fiber is beneficial because it improves digestive functions, prevents constipation and slows the absorption of sugar and carbohydrates, a plus for people who are trying to lose weight.
On the other hand, fiber affects the time it takes to digest food. So eating too much of it may not allow enough time for certain minerals and nutrients to be absorbed into the system. Other consequences of consuming too much dietary fiber at one time are bloating, abdominal cramps and gas.
Sandon goes on to say that although it may seem inconceivable for someone to eat too much fiber -- or in this case, too many apples -- people who are vegan or vegetarian, or who eat a lot of apples while also taking fiber supplements, can find themselves at risk.
"They can easily overdo it if they're not careful," said Sandon.
The same is true for Vitamin C.
Vitamin C, or ascorbic acid, is essential to good health. An antioxidant, the vitamin is necessary for the growth and repair of body tissues, as well as for repairing and maintaining teeth, bones and cartilage. But taking more than 2,000 mg a day can cause stomach pain, diarrhea and gas. In some people, excessive doses can even lead to kidney stones.
Tara Gidus, team dietitian for the Orlando Magic basketball team and owner of Tara Gidus Nutrition Consulting, says she's unaware of anyone who gets too much Vitamin C from his food, though. She says that such a problem often arises when vitamin supplements are misused or abused.
"Again, some people take things to the extreme" said Gidus.
The Catch of the Day
Fish is generally considered a nutritious and healthy food, particularly fatty fish. These fish, rich in oil -- like sardines, salmon or tuna -- are high in omega-3 fatty acids, specifically eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. These essential fats benefit heart health, lower triglycerides and slow the development of atherosclerosis, plaque buildup in the arteries.
On the other hand, omega-3 fatty acids are also mild anticoagulants. Eating too much of these fish can cause a slight thinning of the blood, says Gidus.
For most people, this is not a cause for concern. But for some, it can be risky.
"If you are on blood thinners or have been told by a doctor not to take [fish oil supplements], then use caution," Gidus said.
Even so, it's unlikely a person would experience bleeding problems from dietary omega-3s alone. This tends to be more of an issue for those who get their omega-3 fatty acids from fish oil supplements, which are easier to take to an extreme.
The bigger concern Gidus has about eating too much fish is the mercury levels in many of the fatty fish. She suggests people avoid eating shark, swordfish, tilefish and king mackerel too often. These fish in particular tend to be high in mercury, a heavy metal that can damage nerves and is especially harmful to children and pregnant women.
Wake Up and Smell the Coffee
For some adults, functioning without a cup of coffee in the morning is nearly impossible. And because coffee contains antioxidants, Gidus says some coffee is good.
But coffee also contains caffeine, which in large amounts can raise blood pressure and heart rate. Krieger warns that those who must have numerous cups of coffee to help them get through the day face certain health risks.
"If you already have high blood pressure and you drink a lot of caffeine, it can lead to stroke," she said.
For others, it can cause anxiety and make it difficult to sleep at night. To avoid the negative side effects and risks associated with consuming too much caffeine, both Gidus and Krieger recommend limiting coffee to two cups a day.
The Color of Carrots
While not especially harmful, overindulging in carrots can lead to an unpleasant side effect, says dietitian Joanne Larsen, who operates Ask the Dietitian, a question-and-answer website on nutrition.
Larsen says carrots contain high levels of beta-carotene, a provitamin A carotenoid that the body converts into vitamin A. Because beta-carotene contributes to eye and skin health, enhances a person's immune system and slows the aging process of cells, it is a nutrient that should be in everyone's diet, she says.
But eating large amounts of carrots will not result in greater benefits. The body converts beta-carotene into only the amount of vitamin A it needs. The surplus remains in the system for a time, causing a disconcerting, though harmless, yellow or yellowish-orange hue to the skin.
The condition, called carotenemia or carotenodermia, can also occur when someone drinks too much carrot juice or the juice of other foods high in beta-carotene, such as sweet potatoes, squash, spinach or broccoli.
"Good news is, lay off the foods high in carotene," said Larsen. That's all it takes for your skin to return to its normal color, she says.
Of course, any time people encounter problems because of the food they eat, it raises the issue of proper nutrition and the question of what is being left out of the diet, says Sandon.
Larsen echoes her sentiments. "Any food eaten to excess would not be recommended. That's why we recommend people eat a balanced food plan that includes a variety of foods."
Watch What You Drink
We've heard this one too: Drink plenty of fluids.
The website MayoClinic.com recommends drinking eight 8-oz. glasses of water a day, although notes that the amount of water people need depends on their health, where they live and how active they are.
But Larsen says problems can arise when someone drinks too much fluids. It's an issue more common among athletes, who often sweat a great deal and deplete their systems of water and electrolytes.
"Water to excess can dilute body levels of sodium and even cause death due to water intoxication," Larsen said.
While a healthy body can process anywhere between 10 and 15 liters of fluid a day, athletes run into problems when they drink a lot of water very quickly or drink water without the sufficient electrolytes that the body needs.
Larsen offers this simple guideline on how much water to drink: "Drink enough so that your urine is colorless or light yellow after you wake up in the morning until you go to sleep at night."