The minimum daily requirement for Sodium in an adult is 115 mg.
In consideration of a wide variation of activity and climate, a safe minimum intake might be set at 500 mg a day. US dietary guidelines call for no more than 2000-2400 mg per day (maximum)
Most Americans consume twice that amount.
- 10% comes naturally
- 15-25% from the salt shaker
- 75% from salt added to processed foods
The Salt Institute maintains “Healthy persons with normal BP have no problems with sodium or salt intake.” The claim is1/3 to ˝ of those who already have HTN need to cut back on dietary salt because they are salt sensitive.
They argue that 75% of US population does not have HTN and only a small minority of Americans should be concerned about salt intake. The Salt Institute appears to be winning the public relations battle about salt because a recent survey found that only about 10% of Americans are concerned about their salt intake. But they are not winning the scientific debate about the role of excess salt in promoting HTN and other heart problems.
In 1957 it was shown that increasing salt causes a progressive rise in blood pressure of rats. Rats fed a diet with only 0.15% salt live significantly longer than rats fed greater amounts of dietary salt. A diet with 0.15% salt would provide a person consuming 2500 calories a day with about 300 mg of salt a day. The average American diet is about 2.5% salt on a dry weight basis.
A study of chimpanzees found that the progressive addition of salt to their natural diet resulted in a gradual but significant rise in their BP over 20 months. However within 6 months after their diet returned to normal so did their BP. This evidence from animal studies shows that increasing dietary salt generally causes increased BP.
The Salt Institute likes to point out that only about 1 in 4 American adults has HTN, however BP rises with age and most people will develop HTN in their lifetime and more that ˝ of adult Americans have a BP that is higher than ideal. Is this elevation in BP with age simply a normal part of growing older?
Studies of human populations, which add little or no salt to their food, have found little or no rise in BP with age and a virtual absence of HTN. This immunity to rising BP with age was true for Eskimos and Masai whose diets are high in fat and protein and low in carbohydrates. It was also true for the New Guinea Highlanders and Tarahumara Indians whose nearly vegetarian diets were both very high in carbohydrates.
Given the wide ranges of climates and genetic diversity and extremely varied diet compositions among these populations, it is hard to imagine what factor other than the lack of added salt could be protecting them from HTN. Clearly, then the rise in BP in all Western populations cannot simply be a consequence of normal aging. It appears that excessive dietary salt plays an important role in the development of HTN.
Dr. Malcolm Law, who published a comprehensive review article on the link between salt and HTN in the British Journal of Medicine states “ The effect of universal moderate dietary salt reduction on mortality from stroke and ischemic heart disease would be substantial, larger, indeed than could be achieved by fully implementing recommended policy for treating high blood pressure with drugs.” He also cited that if salt in processed foods was moderately reduced this could “prevent some 70,000 deaths a year in Britain (or 250,000 in the US) as well as much disability.” A safe bet to avoid HTN later in life or help lower your already elevated blood pressure is to try to limit your sodium intake to no more that 1600 mg per day.
Since we have discussed how excess salt and consuming excess salt over a lifetime causes increased BP and elevated BP as Americans grow older, let’s look at some other factors that affect BP and see how important they are for preventing and treating HTN.
The human Paleolithic diet was probably 2-3 times higher in potassium, calcium, and magnesium than that of modern man. The ratio of potassium to sodium was at least 5-10 to 1 in our ancient ancestor’s diet compared to only 0.6 to 1 in the typical American diet today.
Potassium depletion exacerbates HTN so it is important to make sure you are getting enough of this mineral. Potassium is found in a wide range of whole-unprocessed foods, especially fruits, vegetables, beans, milk, poultry and fish.
There are some medications that people with HTN, CHF, and CAD might be taking that could be potassium sparing or potassium wasting. A good idea would be to know how your medications effect these minerals.
There is some evidence that an increase in Omega 3 fatty acids may have a small BP lowering effect. It may be beneficial to include a couple of servings of high omega 3 fatty acid fish each week in your diet.
In regards to alcohol, 1 or 2 drinks a day have little effect on BP. Alcohol in excess of 2 drinks a day tends to increase cardiac output, which mainly increases systolic BP. When consumption is discontinued, the drop in systolic BP can take several weeks.
- Smoking increases heart rate and cardiac output and causes a transient rise in systolic BP.
- Stress and noise cause a transient rise in BP. There is little or no evidence that they play a significant role in causing HTN.
- Exercise causes a transient rise in BP. It does not lead to the development of HTN. Regular exercise helps prevent the development of HTN perhaps by increasing salt excretion in the sweat and aiding weight loss.
The DASH Study found that a low-fat diet with more fruits, vegetables and low-fat dairy products can substantially lower BP even though salt intake was modest. The DASH Study concluded that this diet offers an additional nutritional approach to preventing and treating HTN.
To maximize BP lowering and to prevent HTN from developing it is the combination of all safe and effective lifestyle changes that will prove most successful. It now appears that a low-salt diet coupled with plenty of fruits, vegetables, whole grains and non-fat dairy products and perhaps a little fish is best for treating and preventing essential HTN because it promotes weight loss without hunger and increases the ratio of potassium, calcium, and magnesium to salt. This more nearly reflects the nutritional needs of humans.
Calcium supplements are a good idea, but we strongly suggest that you get some calcium and all your potassium and magnesium from foods, which also contain other nutrients you need. Non fat dairy products and leafy greens are good sources of calcium. You need at least 800-1000mg of calcium day; women over 50 and men over 65 need 1500 mg daily. Potassium is plentiful in most foods. Magnesium is plentiful in whole grains, leafy greens, milk, beans, bananas and nuts.
June is National Fruit and Vegetable Month, which perfectly coincides with the DASH eating plan and the diet that we have been promoting with the Arrest and Reversal Program. Everyone could stand to eat more fruits and vegetables since they contain an abundance of vitamins, minerals, and antioxidants, phytochemicals, fiber and other cancer preventing substances.
Try this 5 week plan to help you consume more fruits and vegetables.
- Week 1 – focus on breakfast. Try to eat a different serving of fruit each day. Eat the fruit alone or on top of cereal or yogurt.
- Week 2 – focus on your midmorning snack. Try to include fruits and vegetables in all your snacks. Keep fruit and vegetable sticks on hand for quick, easy snacking.
- Week 3 – focus on lunch. Double the amount of lettuce and tomatoes your put on your sandwiches. If you eat lunch out, ask them to cut the mayo and double the veggies. Always have a piece of fruit along with your meal.
- Week 4 – focus on dinner. Try to include 2-3 servings of vegetables with every dinner you eat this week. Incorporate fruit into your dinner by serving fruit salsas or putting fruit in your salad.
- Week 5 –focus on dessert. Make fruit desserts this week. Keep washed and cut up fruit on hand for fresh fruit cups.