The following text is for questions 27 to 30.

    Junk food is very popular in today's life because it is quite practical. However, consuming junk food for our daily meals will cause many problems for our bodies.

    The first problem is strokes. Junk food, such as potato chips, fries and pepperoni pizza, contains much sodium, which may increase your risk of a stroke. You need some sodium in your diet to help maintain normal fluid balance, but too much sodium increases blood pressure and stroke risk. You should not consume more than 1,500 milligrams of sodium each day for your optimal heart health. If you have a weakness for potato chips, opt for low-sodium or salt-free varieties to lessen your sodium intake.

    The second problem is weight gain. Junk food will result in you becoming overweight. It will add an extra 3,500 calories to your daily diet. If you consume 500 calories from junk food each day, it will lead to 1 pound of weight gain in just a week.

    In addition, junk food will cause tooth decay. Most junk food contains high sugar levels, which cause cavities in your teeth because sugar will coat your mouth, tongue, and teeth. This sugar coating attacks enamel, a tissue that constitutes much of a tooth, and leads to tooth decay and cavities.

    Finally, it causes gastrointestinal problems. Junk food contains less fiber. Fiber is very important to our digestive system. If you don't get adequate amounts of fiber, you may suffer from constipation. When this occurs, you may go for days without having a bowel movement or have difficulty passing stools.

    From the facts above, it is obvious that junk food does not bring any benefits to our bodies. 

" ... to lessen your sodium intake." (Paragraph 2)

What does the underlined word mean?