Carbohydrates are the sugars, starches and fibers found in fruits, grains, vegetables and milk products. Though often maligned in trendy diets, carbohydrates — one of the basic food groups — are important to a healthy diet.
There are three macronutrients: carbohydrates, protein and fats. Macronutrients are essential for proper body functioning, and the body requires large amounts of them. All macronutrients must be attained through diet; the body cannot produce macronutrients on its own.
The recommended daily amount (RDA) of carbs for adults is 135 grams, according to the National Institutes of Health (NIH); however, the NIH also recommends that everyone should have his or her own carbohydrate goal. Carb intake for most people should be between 45% and 65% of total calories. One gram of carbohydrates equivalents about 4 calories. So a diet of 1,800 calories per day would equal about 202 grams on the low end and 292 grams of carbs on the high end. However, people with diabetes should not eat more than 200 grams of carbs per day, while pregnant women require at least 175 grams.
Two basic compounds make up carbohydrates:
Aldehydes: These are double-bonded carbon and oxygen atoms, plus a hydrogen atom.
Ketones: These are double-bonded carbon and oxygen atoms, plus two additional carbon atoms.
Carbs can combine together to form polymers, or chains.
These polymers can function as:
There are numerous types of carbohydrate. They include monosaccharides, disaccharides, and polysaccharides.
This is the smallest possible sugar unit. Examples include glucose, galactose, or fructose. Glucose is a major source of energy for a cell. “Blood sugar” means “glucose in the blood.”
In human nutrition, these include:
galactose, most readily available in milk and dairy products
fructose, mostly in vegetables and fruit
Disaccharides are two monosaccharide molecules bonded together, for example, lactose, maltose, and sucrose.
Bonding one glucose molecule with a galactose molecule produces lactose. Lactose is commonly found in milk.
Bonding one glucose molecule with a fructose molecule, produces a sucrose molecule.
Sucrose is found in table sugar. It is often results from photosynthesis, when sunlight absorbed by chlorophyll reacts with other compounds in plants.
Different polysaccharides act as food stores in plants and animals. They also play a structural role in the plant cell wall and the tough outer skeleton of insects.
Polysaccharides are a chain of two or more monosaccharides.
The chain may be:
branched, so that the molecule looks like a tree with branches and twigs.
unbranched, where the molecule is a straight line.
Polysaccharide molecule chains may consist of hundreds or thousands of monosaccharides.
Glycogen is a polysaccharide that humans and animals store in the liver and muscles.
Starches are glucose polymers that are made up of amylose and amylopectin. Rich sources include potatoes, rice, and wheat. Starches are not water soluble. Humans and animals digest them using amylase enzymes.
Cellulose is one of the main structural constituents of plants. Wood, paper, and cotton are mostly made of cellulose.
Vegetables: All of them. It is best to eat a variety of vegetables every day.
Whole fruits: Apples, bananas, strawberries, etc.
Legumes: Lentils, kidney beans, peas, etc.
Nuts: Almonds, walnuts, hazelnuts, macadamia nuts, peanuts, etc.
Seeds: Chia seeds, pumpkin seeds.
Whole grains: Choose grains that are truly whole, as in pure oats, quinoa, brown rice, etc.
Tubers: Potatoes, sweet potatoes, etc.
People who are trying to restrict carbohydrates need to be careful with the whole grains, legumes, tubers and high-sugar fruit.
Sugary drinks: Coca cola, Pepsi, Vitamin water, etc. Sugary drinks are some of the unhealthiest things you can put into your body.
Fruit juices: Unfortunately, fruit juices may have similar metabolic effects as sugar-sweetened beverages.
White bread: These are refined carbohydrates that are low in essential nutrients and bad for metabolic health. This applies to most commercially available breads.
Pastries, cookies and cakes: These tend to be very high in sugar and refined wheat.
Despite their bad rap, carbohydrates are vital to your health for a number of reasons.
Carbohydrates are your body’s chief fuel source. During digestion, sugars and starches are broken down into simple sugars. They’re then absorbed into your bloodstream, where they’re known as blood sugar (blood glucose).
From there, glucose enters your body’s cells with the help of insulin. Glucose is used by your body for energy, and fuels all of your activities — whether it’s going for a jog or simply breathing. Extra glucose is stored in your liver, muscles and other cells for later use, or is converted to fat.
Protecting against disease
Some evidence suggests that whole grains and nutritional fiber from whole foods help reduce your risk of cardiovascular diseases. Fiber may also protect against obesity and type 2 diabetes. Fiber is also important for optimal digestive health.
Study shows that eating plenty of fruit, vegetables and whole grains can help you control your weight. Their bulk and fiber content aids weight control by helping you feel full on fewer calories. Contrary to what low-carb diets claim, very few studies show that a diet rich in healthy carbohydrates leads to weight increase or obesity.
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