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A Pinch of Salt – The Rest of the Story

An overweight man getting his blood pressure checked. (Digital Vision/Thinkstock)
An overweight man getting his blood pressure checked. (Digital Vision/Thinkstock)

In my column last week, I discussed the adverse effects of dietary salt on your health. The conclusion was that if you want to stay healthy and have your blood pressure under control then you need to eat less than one teaspoon table salt a day.

After that, a reader sent me a link to a Scientific American article, “It’s Time to End the War on Salt,” written by Melinda Wenner Moyer.

Moyer says, “The zealous drive by politicians to limit our salt intake has little basis in science.”

Moyer’s argument is based on a meta-analysis of seven studies involving a total of 6,250 subjects in the American Journal of Hypertension found no strong evidence that cutting salt intake reduces the risk for heart attacks, strokes or death in people with normal or high blood pressure.

Moyer goes on to quote several more studies from all over the world. She goes on to say, “These findings call into question the common wisdom that excess salt is bad for you, but the evidence linking salt to heart disease has always been tenuous.” She concludes the article by saying there is little evidence for long-term benefit from reducing salt intake.

Point well taken. However, there is evidence that shows too much or too little salt in the diet can lead to muscle cramps, dizziness, or electrolyte disturbance, which can cause neurological problems or death. Generally, more emphasis is given to the evidence showing an association between salt intake and blood pressure among adults. We also know reduced salt intake results in a small reduction in blood pressure. Evidence suggests that high salt intake causes enlargement of the heart and swelling of the legs. The evidence may be tenuous but it is there.

Like many things in science and particularly in medicine, strong evidence is lacking in many of the things doctors advise their patients about good health. Some advice is based on “tenuous” evidence as there is nothing better to suggest. When we have strong evidence that certain habits can lead to bad health and even cancer (e.g. smoking, sun worshipping) generally people ignore the advice.

The story of salt intake is a just a small pinch in the overall story of healthy eating and exercise in maintaining good cardiovascular system and good health. The message is, eat in moderation, it is not what you do and eat, it is how much you do and eat to stay healthy and happy.

Less salt won’t hurt you. Too much salt is not good for you.

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Salty Advice About Dietary Salt

A spilled salt shaker. (iStockphoto/Thinkstock)
A spilled salt shaker. (iStockphoto/Thinkstock)

None of us are strangers to table salt. Everytime you eat something, you probably make a remark regarding the amount of salt in the food. Some people may think it is just right, some may find it too salty and some may feel extra salt is required.

Our body contains many salts. Table salt (sodium chloride) is a major one making up around 0.4 per cent of the body’s weight at a concentration pretty much equivalent to that in seawater. Somebody has calculated a 50 kg person would have around 200 gm of sodium chloride in his body. That makes around 40 teaspoons.

We continually lose salt when we lose water from our body as salt is in a solution. So when we are sweating, vomiting, having diarrhea or voiding water by act of urination, we are losing salt. Salt cannot be made in our body so we have to replenish it otherwise there can be serious consequences.

Salt is needed to maintain our blood volume and blood pressure. Sodium is also needed for nerves and muscles to work properly. Low levels of body sodium can make our brain swell and cause confusion.

Too much sodium is bad for us as well. Excessive consumption of sodium can increase blood pressure, and that salt is a major determinant of population blood pressure levels. Some research estimates suggest the numbers of deaths averted by moderate reductions in population salt consumption would be at least as many as those achieved by plausible reductions in population smoking rates (CMAJ June 12, 2012).

The fast food industry is making its own contribution towards increasing the general population’s salt intake. Fairly large population is relying on fast food industry to provide their daily food needs. Fast food tends to be more energy dense, contain more saturated fat and salt, contain fewer micronutrients and be eaten in larger portions than other foods, says the CMAJ article.

Fast food items such as fried potatoes, pizzas and sugar-sweetened soft drinks typically provide between one-third and one-half of daily energy intake but less than one-quarter of most micronutrients.

Now what? Too much or too little salt in the diet can lead to muscle cramps, dizziness, or electrolyte disturbance, which can cause neurological problems, or death. Generally, more emphasis is given to the evidence showing an association between salt intakes and blood pressure among adults. We also know reduced salt intake results in a small reduction in blood pressure. Evidence suggests that high salt intake causes enlargement of the heart and swelling of the legs.

There is a clear scientific evidence that a modest and long term reduction in population salt intake can result in a lower population blood pressure, and a reduction in strokes, heart attacks and heart failure.

Then what are we waiting for? Most of us consume more salt than we need. General recommendation is no more than six grams (about one teaspoon) of table salt a day. This includes salt used in cooking and at the table. If you have high blood pressure or heart disease then less than two grams of table salt per day will be helpful. Are you willing to try that?

So, how is your food tasting today?

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There is a Price to Pay for Physical Inactivity

An overweight man sitting on a bench with take-out food. (Digital Vision/Thinkstock)
An overweight man sitting on a bench with take-out food. (Digital Vision/Thinkstock)

An article in the Lancet (July 21 2012) says worldwide mortality rate of inactivity is about one per cent which is same as mortality from smoking.

It says exercise has been called a miracle drug that can benefit every part of the body and substantially extend lifespan. Yet it receives little respect from doctors or society. This passive attitude towards inactivity, where exercise is viewed as a personal choice, is anachronistic, and is reminiscent of the battles still being fought over smoking.

Inactivity in our society is reaching pandemic proportion and has far reaching health, economic, environmental and social consequences, says the Lancet paper.

Is it too difficult to exercise two hours and thirty minutes a week? That is the recommended amount of time we should be physically active each week. Would you be surprised if I say only 15 per cent of the Canadians meet this goal? Yes, that is true. Only 15 per cent of us are physically active for two-and-half hours each week.

An average Canadian spends more than two hours watching television every day. Come to think of it, physical activity can be as easy as watching television. You can incorporate physical activity in your daily routine – going shopping, walking your children to school, delivering newspapers and visiting a friend. These are just a few examples. You can do more if you can. The more you do the better it is.

In 2005, Time magazine did a survey to see what kind of physical activity Americans like to do. The survey revealed 69 per cent take a brisk walk, 35 per cent use exercise machine, 32 per cent lift weights, 30 per cent ride a bike, 27 per cent jog or run, 22 per cent do aerobic exercise, 21 per cent swim, 19 per cent dance, 18 per cent play some kind of sport like soccer, 18 per cent go hiking, eight per cent play golf, seven per cent do yoga and seven per cent bowl.

Physical activity has many benefits. We know that. Smoking is harmful. We know that too. Yet we continue to be couch potatoes and we continue to smoke. What is the solution? Let us keep moving and stop smoking. Isn’t that easy?

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How much vitamin D do you need daily to prevent fractures?

A vitamin capsule. (iStockphoto/Thinkstock)
A vitamin capsule. (iStockphoto/Thinkstock)

Basking in the sun is one way to obtain vitamin D

Basking in the sun is one way to obtain vitamin D although the risk of skin cancer increases. Other sources of vitamin D are fortified dairy products, fatty fish and egg yolks.

Answer to this question appears in an article in the New England Journal of Medicine (NEJM) published in July, 2012. The authors examined the relationship between vitamin D supplementation and fracture reduction.

They looked at 11 double-blind, randomized, controlled trials of oral vitamin D supplementation (daily, weekly, or every 4 months), with or without calcium, in persons 65 years of age or older. The goal was to look for the incidence of hip and any nonspinal fractures.

The study included 31,022 persons (mean age, 76 years; 91 per cent women) with 1111 incident hip fractures and 3770 nonspinal fractures.

When they looked at a subgroup of participants by actual intake of vitamin D, they found reduction in the risk of fracture was shown only at the highest intake level (median, 800 IU daily; range, 792 to 2000), with a 30 per cent reduction in the risk of hip fracture and a 14 per cent reduction in the risk of any nonspinal fracture.

“Benefits at the highest level of vitamin D intake were fairly consistent across subgroups defined by age group, type of dwelling, baseline 25-hydroxyvitamin D level, and additional calcium intake,” says the NEJM paper.

The conclusion of the study was that high-dose vitamin D supplementation (≥800 IU daily) was somewhat favorable in the prevention of hip fracture and any nonspinal fracture in persons 65 years of age or older.

As we know, vitamin D is a nutrient that helps the body use calcium and phosphorous to build and maintain strong bones and teeth. Vitamin D is unique in that it can be synthesized by the body after exposure to ultraviolet rays from sunlight.

Too much vitamin D can cause too much calcium to be deposited in the body, which can lead to calcification of the kidney and other soft tissues including the heart, lungs and blood vessels. But it is hard to define what is too much. Some expert recommend daily intake of 1000 to 2000 IU of vitamin D to prevent certain types of cancers.

Health Canada’s recommendation for daily dietary intake of vitamin D in adults age 70 and over is 800 IU (20 mcg). This is based on the assumption that there is minimum of exposure to sunlight. The major sources of vitamin D are fortified foods. In Canada, cow’s milk and margarine must be fortified with vitamin D. The only natural sources of vitamin D in the Canadian food supply are fatty fish and egg yolks.

Many people meet at least some of their vitamin D needs through exposure to sunlight. Although there is some risk of skin cancer. But you never know how much vitamin D you are getting through sun exposure. It all depends on the season, time of day, cloud cover, smog, skin pigmentation, and sunscreen use.

Daily intake of vitamin D recommendation depends on a person’s age. Talk to your doctor or see Health Canada website for more details. But do not forget to drink your milk everyday.

Start reading the preview of my book A Doctor's Journey for free on Amazon. Available on Kindle for $2.99!