6.2
Explore an Issue in chemical Quantities
SkILLS MEnu
• Defining the
Issue
• Researching
• Identifying
Alternatives
• Analyzing
• Defending a
Decision
• Communicating
• Evaluating
overdosing on Salt
Salt is a silent killer. Millions of people worldwide die each year from complications
caused by consuming too much salt. What makes these deaths so unfortunate is
that most are preventable. Prevention starts with saying “no” to the salt shaker and
making wiser choices at mealtime. A World Health Organization study predicts that a
reduction of only 15 % in daily salt intake over a 10-year period would save 9 million
lives. This is just a few grams less, per person, each day.
As you recall, table salt is mostly sodium chloride, NaCl: an ionic compound.
The sodium ions in sodium chloride are the real cause of the problem. Sodium is a
required nutrient. Sodium ions help regulate fluid levels in the body and allow nerves
and muscles to operate effectively. However, excess sodium ions make the body retain
water. Extra fluid increases blood pressure, which makes it more difficult for the
heart to push blood throughout the body (Figure 1). This may damage the heart and
increase the risk of heart attacks and cardiovascular disease.
According to Health Canada, the average Canadian consumes about 3400 mg of
sodium per day. This quantity is more than twice Health Canada’s recommended
daily intake of 1500 mg, and almost 50 % greater than the maximum tolerable limit
of 2300 mg. These quantities may sound large, but they represent much less than a
teaspoonful of salt (Figure 2).
(a)
Figure 1 A typical healthy person has
a blood pressure of 120/80 mmHg
(millimetres of mercury). Excess dietary
salt can elevate blood pressure.
(b)
Figure 2 (a) A Canadian’s average daily consumption of salt and (b) the recommended daily intake
Using the salt shaker less frequently is one way to reduce your salt intake. However,
a French study showed that only about 10 % of dietary salt is added during home
cooking or at the table. The remaining 90 % is hidden in the processed foods that we
eat. That is why it is so important to read product labels when choosing foods, and to
choose fresh foods rather than processed products (Figure 3).
A recent study of Canadian Inuit verified a link between processed foods and high
blood pressure. The traditional Inuit diet of fish and sea mammals is low in sodium.
Consequently, the incidence of high blood pressure among Inuit has historically been
below that of the general Canadian population. However, as Inuit consume more processed, store-bought foods, they are increasingly suffering from high blood pressure.
Figure 3 This meal contains most of the entire recommended daily intake of salt.
264
Chapter 6 • Quantities in Chemical Formulas
NEL
The Issue
As more students adopt healthier lifestyles, it is important that they are aware of
what is in the food they consume. This applies to the school cafeteria as well as in
the home.
goal
To develop a strategy to reduce salt consumption at school (including food prepared
at home or in the cafeteria)
research
SKILLS
HANDBOOK
A5.1
Work in pairs or in small groups to learn more about dietary salt. Research the following topics:
•
•
•
•
•
•
other medical conditions that are linked to an excess of dietary salt
reasons that salt is added to food
types of foods that are particularly high in salt
some simple strategies that can reduce dietary salt intake
other sources of sodium in food, beside table salt
alternatives to salt, and their health effects
CarEEr LInk
Food chemists are involved in
deciding how much salt, and other
additives, is included in processed
foods. If you want to know more
about the career of a food chemist,
go T o n ElS on S C i En C E
wEb LInk
To start your research on salt in
the diet,
Identify Solutions
Consider a variety of strategies to find the best way of reducing students’ salt intake
in the school cafeteria. They could include the following:
go T o n ElS on S C i En C E
• raising student awareness of the health risks of excess salt intake
• posting information about the nutrient content of cafeteria food
• discussions with the cafeteria management about lowering the salt content of
cafeteria food
• increasing the student demand for healthier food choices
Make a Decision
Based on your discussions and research, what approach would you recommend for
bringing about a reduction in the salt intake in the school cafeteria?
Communicate
Summarize your recommendations in a report that forms the guidelines for your
school’s action plan to “halt the salt”—or at least to reduce it.
Plan for Action
How could you get your action plan implemented in your
school? One way might be to collect evidence, showing how
two similar (and great-tasting) meals can contain very different
quantities of salt.
1. Plan two lunches: one consisting mainly of processed foods
and another of mostly unprocessed foods. Try to make
the meals as comparable as possible. For example, if you
select breaded chicken strips in the processed lunch, use
a similarly sized portion of chicken breast in the other. (No
purchases are necessary.)
NEL
2. Use product labels or other sources of nutrition data to
calculate the total mass of sodium, in milligrams, in each
meal.
3. Prepare to implement your salt reduction action plan.
Decide whom you need to convince, to put your plan
into action. Have your evidence on hand to support your
proposal. Always discuss your plans with your teacher
first. Launch a campaign to make your school more
“salt savvy.”
go To n ElS on S C i En C E
6.2 Explore an issue in Chemical Quantities
265