The Source - Nutrition Note: Healthy Eating for Your Heart

Annually, 15.3 million deaths occur due to cardiovascular disease (CVD)⁶. However, we can reduce our risk of CVD by lowering our risk factors. Scientific research has helped to understand the risk factors of CVD and the lifestyle attributes that prevent CVD. On going research is still required to validate and expand the knowledge base. When institutions try to come to a consensus on what should be the recommended lifestyle and diet to help prevent CVD, many forces are at work to shape the policy. Different scientific views and special interest groups all desire a contribution to the end result. This is why some recommendations differ between organizations and countries.

With this in mind, this article will try to explain the commonalities of most viewpoints with a focus on diet. The risk factors associated with CVD are well established ^{4 6}. They include the following:

As the level of risk increases, the need for intervention also increases. Focusing on a healthy diet is very important in helping to reduce many of the risk factors associated with CVD. The food pyramid is a good starting point for such a diet. However, the pyramid and its serving size must be understood to be useful and effective, otherwise under eating or overeating of certain food groups can occur. [For guidance on using the food pyramid, please see the series of articles in "The Source" starting February 2002]. In addition, the food pyramid lacks guidance on salt, alcohol, and the type of fat to consume.

Below is a review of the different dietary compounds and their effect on CVD.

Many studies have indicated the importance of increasing the consumption of fruit and vegetables to reduce CVD risk ^{4 6}. An increased consumption of fruit and vegetables has been found to reduce blood pressure. Vegetables contain dietary fibre, vitamins, plant sterols, and potassium, which are important for a heart healthy diet. Plant sterols are a type of plant fat that has been shown to lower serum cholesterol levels. However, studies are needed to understand the long term consequences of consuming plant sterols. Soy products and flavonoids have a possible role in decreasing CVD risk⁶.

Daily intake of 400 - 500 g of fruit and vegetables is recommended. This level can be met by following the recommendations and serving sizes for fruits and vegetables in the food pyramid.

Dietary fibre is found in fruit, vegetables and grain products. Consumption of grains has a probable supporting role in decreasing CVD risk, due to lowering total cholesterol and LDL cholesterol⁶. Patients with high levels of LDL cholesterol should consume 10 – 25 g/day of viscous soluble fibre⁴. Examples of soluble fibre are dried beans, oats and fruits¹. Diabetics need to consider a diet that lowers blood glucose (hypoglycaemic diet) thereby improving blood glucose control and reducing CVD risk ³.

A source of protein is necessary in a balanced diet. Consumption should focus on fish ^{4 6}, lean meats, and legumes⁴ . A study looking at data from 36 countries noted that fish consumption reduced death rates attributed to all causes, including CVD. A small daily consumption of fish may be beneficial to high risk individuals⁶.

Disappointingly, well controlled studies have shown no benefits of antioxidants in reducing CVD. For example, vitamin E, (an antioxidant) was found to have no effect on CVD in both men and women. In high risk patients, vitamin E, vitamin C (an antioxidant), and beta carotene supplementation gave no significant benefit ⁶.

Some evidence shows that the vitamin folate, which has the ability to decrease homocysteine levels (see In the News: Feb 14, 2002 for a definition of homocysteine) has a positive role on decreasing CVD. However, current debate exists over if high homocysteine levels are the cause or effect of atherosclerosis. Folate maybe working through another mechanism to lower CVD and stroke.

High blood pressure is a known risk factor for CVD and salt intake is directly related to blood pressure. Numerous studies around the world indicate lowering salt intake reduces the need for antihypertensive drug and reduces the number of deaths attributed to stroke and CVD. Salt should be limited to less than 5 gm per day from all sources⁶ or less than 2400 mg of sodium.

Saturated fats are known to increase total cholesterol and LDL cholesterol, however more specifically the saturated fats with the most damaging effects are called myristic and palmitic. These fats can be found in high levels in dairy products, meat, coconut and palm oil. Low dairy fat products and lean meat should be consumed ⁵. Manipulation of cattle diets has shown promise in changing the fat profile (commonly called the fatty acid profile) of the meat and dairy products. However, currently high costs for special cattle diets with no financial return inhibit implementation of this change.

Recommendations for humans are to decrease saturated fat intake to below 10% of the total daily calories. For those people at high risk of CVD, as indicated by high LDL cholesterol, should decrease saturated fat intake to below 7% of total calories.

Saturated fat should be replaced with unsaturated fat, such as the polyunsaturated fats (commonly called PUFAs) found in fish and fish oils, or monounsaturated fats found in olive oil and canola oil, and some nuts. Increasing foods with high levels of linoleic acids is also recommended, ⁶ which are found in foods such as soybean and sunflower oils.

Trans fatty acids are unsaturated fats, but look like saturated fats. Trans fatty acids have been found to increase LDL cholesterol and decrease HDL cholesterol, which is the exact opposite of what a healthy diet should try to achieve. Trans fatty acids are found in hydrogenated oils such as shortening and some margarine, and are commonly used to deep fry food and in baked goods ^{4 5 6}.

A person’s cholesterol level is a reflection of both diet and the production of cholesterol in the body. The level of cholesterol production in the body has a heritable component. Major sources of cholesterol are dairy products, meat, crustaceans, and eggs. Controversy still exists over dietary cholesterols role and CVD. However for now, current recommendations for healthy people are to consume less than 300 mg/day of cholesterol. Those people with high LDL cholesterol should limit intake to 200 mg/day.

One practical hint is to remove the skin from poultry prior to cooking, which will result in a lower intake of both saturated fat and cholesterol.

The low fat hype has not resulted in a slimmer society. This may be due to the consumption of hidden fats, however it may also be attributed to an increased consumption of refined carbohydrates. People need to match their caloric intake to their caloric needs. This includes calories coming from fat as well as from carbohydrates and protein. If overweight, less total calories will need to be consumed to reach optimal body mass index. For an overweight/obese patient, decrease body weight by 10% within the first year of therapy⁶.

Alcohol is not a necessary nutrient for a healthy body. Moderate intake of alcohol has been shown to increase HDL cholesterol. However by limiting alcohol consumption to a moderate level, a person can reduce their CVD risk ^{4 6}.

From a practical point of view, what would a daily menu of a heart healthy diet look like? For a moderately active person who is not a high risk CVD candidate, the menu of the day may be:

1 ½ multigrain English muffin
jam and butter (1 tbsp each)
1 glass of orange juice
1 glass of water

2 glasses of water
1 glass of milk (low fat)
Mixed salad greens with low calorie dressing
Chicken sandwich on multigrain bread

1 glass of white wine (optional)
2 glasses of water
Salmon steak on a bed of cooked spinach
Rice pilaf
Steamed broccoli
Cooked carrots
Fresh strawberries and cantaloupe with low fat yoghurt topping

Multigrain roll
2 glass of water

Total calories
Protein
Dietary fibre
Total fat
Saturated fat
Cholesterol
Sodium

1850
99 gm
17 gm
22.8% of total calories
5.2% of total calories
163 mg
2885 mg

The above diet is not perfect as it is a bit high in protein and sodium. The total sodium intake should only be 2400 mg. Notice how no table salt was added, but the sodium level was still above the recommended level. This diet was constructed on an interactive healthy eating index that can be found at http://147.208.9.133/. Play with this site and learn how your diet stacks up.

This article focused on a balanced healthy diet with respect to cardiovascular disease; however a balanced diet is also required for growth and maintenance of the body, and for prevention of other chronic disease such as cancer, diabetes, osteoporosis, obesity, and dental disease.