Dietary salt – where is it usually from?

Salt (sodium) intake is one of the most important causes of hypertension. Cardiologists often advise reducing salt as a way of dealing with hypertension. But where does salt in our diet usually come from?

An American study from the University of Minnesota suggests that at least for Americans, 70% of dietary sodium comes from foods prepared outside the home.  Sodium found naturally in foods consumed accounts for 14%, and salt added in the course of preparing food at home amounts to 5.6% of intake.  Saltshakers at the home table account for 4.9% of ingested sodium. The overall sodium consumption was more than 50% over the recommended amount.

These researchers gathered data from people from Birmingham, Alabama; Palo Alto, California; and Minneapolis-St Paul, Minnesota; aged 18 to 74 across diverse racial groups. While the sample may not necessarily be representative of our New Zealand population, the findings do remind us that one of the best ways of reducing salt intake may be to cook hearty meals at home, rather than spending money dining out.

Reference:

Harnack LJ, Cogswell ME, Shikany JM, et al. sources of sodium in US adults from 3 geographic regions. Circ 2017; 135:1775-1783

Plant-based diet = healthy?

Many believed that simply avoiding meat would constitute a healthy diet.   A recent study from the Harvard School of Public health suggests otherwise.  Plant-based diet must be of “high quality”, in order to reduce coronary heart disease risk.

The study followed more than 200,000 adults for two decades. 

-       A plant-based diet rich in whole grains, fruits, vegetables, nuts and legumes was associated with a substantially lower coronary heart disease risk. 

-       A plant-based diet rich in refined grains, fruit juice, potatoes, sweets and sugar-sweetened beverages was associated with a substantially higher coronary heart disease risk.

Sticking to a healthy diet can sometimes be quite difficult. However, this study further adds to our knowledge of what is healthier and what is less healthy.

For those who consume a large amount of “unhealthful” plant-based foods, this study is a reminder that vegetarian foods may not always be healthy.

For those who want to improve their diets but cannot adopt a vegetarian diet, the good news is that one could probably concentrate on replacing a couple of servings of unhealthy animal foods by a couple of servings of healthy plant-based foods, and still benefit. Nothing too extreme.

Reference:

Satija A, et al. Healthful and unhealthful plant-based diets and the risk of coronary artery disease in US adults. J Am Coll Cardiol 2017; 70:411-422.

Yum char – balanced diet?

Maintaining heart health requires a balanced diet.

In a previous blog post, we explained the “food plate”, which is an easy-to-understand illustration on how best to achieve the balanced diet.  The simple rule of thumb is to consume 50% vegetables; with the rest made up of some grains, starchy vegetables such as potato, some proteins, some milk, yoghurt and cheese, and the rest healthy oil, nuts and seeds.

Yum char is hugely popular in Chinese. From the heart point of view,

-       multiple small plates make it quite hard to work out the right food group proportions

-       many dim sums contain high overall fat content, especially saturated fat

-       many dim sums contain very high salt content.

The Food and Environmental Hygiene Department of Hong Kong studied the nutrient values of Chinese dim sum in 2007. 

Rather than listing the nutrient values of all popular items here, we have picked a few interesting (and sometimes surprising) lists below.

High total fat Chinese dim sum

-       Steamed beancurd sheet roll (鮮竹卷), 1 piece, 12g fat, 72% energy from fat

-       Pan-fried beancurd sheet roll (煎腐皮卷), 1 piece, 11g fat, 76% energy from fat

-       Steamed minced beef ball (山竹牛肉), 1 piece, 7g fat, 67% energy from fat

Commentary: Pan-fried and deep-fried Chinese dim sum was high in total fat. However, among 37 savoury Chinese dim sum prepared by steaming, the percentage energy from total fat of 12 Chinese dim sum was more than 50%.

High saturated fat Chinese dim sum

-       Coconut milk yellow bean pudding (椰汁馬豆糕), 1 piece, 3g saturated fat, 24% energy from saturated fat

-       Mango sago dessert with pomelo (楊枝甘露), 1 bowl, 5g saturated fat, 20% energy from saturated fat

-       Baked barbecued pork puff (叉燒酥), 1 piece, 4g saturated fat, 20% energy from saturated fat

Commentary: Chinese dim sums with coconut milk, or lard contain very high saturated fat

High salt content Chinese dim sum

-       Steamed chicken with fish maw (棉花雞), 640mg sodium/100g

-       Steamed curry squid (咖哩蒸魷魚), 640mg sodium/100g

-       Steamed chicken feet with black bean sauce (豉汁蒸鳳爪), 620mg sodium/100g

Commentary: High-sodium condiments, such as table salt, black bean sauce, and mono-sodium glutamate, contributed to the high sodium contents.

The most interesting part of the study was its recommended healthier menus. See page 18 of the document. Below is the suggested menu for 4 people. The main highlight of these menus is having half a plate of boiled vegetables for each diner, to achieve the right balance.

How close is this to what we ate last week at yum char?

Steamed glutinous rice roll (糯米卷), 2 pieces

Steamed barbecued pork bun (叉燒包), 3 pieces

Steamed rice-roll with shrimps (鮮蝦腸粉), 3 rolls

Boiled water spinach (白灼通菜), 1 plate

Boiled Chinese flowering cabbage (白灼菜心), 1 plate

Steamed stuffed dumpling with shrimp/ Siu mai (燒賣), 4 pieces

Sesame dessert/sweet soup (芝麻糊), 2 bowls

Alcohol & Calories

The cardiovascular effects of alcohol are often debated. One commonly neglected aspect is its caloric content.

Alcohol contains 7 calories per gram, compared with fat that contains 9 calories per gram and sugar that contains 4 calories per gram.

As a simple guide, a pint of beer and a glass of wine contain approximately 150-200 calories.

These are the foods that roughly contain 150-200 calories:

-       1 large bag of potato chips

-       1 large sugar-coated doughnut

-       1 slice of pizza

-       1 chicken drumstick

-       1 Tip Top Jelly Tip icecream

-       4 Yorkshire puddings

A simple google search on “alcohol calorie” would yield a variety of useful graphics, e.g. from the BBC. Northland DHB also has a nicely written article on this.

Author: Dr Andrew To

Are cardiologists obsessed with statins?

Cardiologists know of the beneficial effect of statins, the main class of medications to lower cholesterol and prevent heart attacks.  Much of the evidence has been from randomized controlled trials over the last 10-20 years, where patients treated with statins were less likely to have a heart attack compared with those who were not.

An interesting study from Denmark now gives us solid evidence about the beneficial effect of statins in real-life patients. Denmark has nationwide medical records of all patients.  In this analysis, all Danish patients who were started on statins have been included from 1995 to 2010.

The most important message from the study was that those who stopped statins early were 26% more likely to have a heart attack and 18% more likely to die, during follow-up.  These figures are convincing, especially considering that it comes from ALL patients in Denmark during that period of time.

Reference:

Nielsen SF, Nordestgaard BG. Negative statin-related news stories decrease statin persistence and increase myocardial infarction and cardiovascular mortality: a nationwide prospective cohort study. Eur Heart J. 2015 Dec 1.  PMID: 26643266

Author:

Dr Andrew To

Healthy Diet for the Heart – Food Avoidance vs. Balanced Diet

After a heart attack, many patients ask their cardiologists what foods to avoid. However, one may not realize that food avoidance is not what cardiologists preach. After all, food is something we enjoy, so the focus should never be what we cannot eat, but rather how we should eat. It is about a balanced diet.

The key to healthy eating is to learn what foods are the best, what foods are good, what foods are not so good. The new Healthy Heart visual food guide from the Heart Foundation is a very practical way of striking that balance and is worth spending some time studying it.

Some important points worth mentioning include:

-       Starchy vegetables such as potato and kumara count towards starchy foods like breads, grains and rice.

-       Not all fats are off-limit. Polyunsaturated fat, such as nuts and vegetable oils (except palm oil and coconut oil), is important for heart health.

For more information, please visit the heart foundation website. 

Echocardiography

Echocardiogram gives information about the heart muscle and valve functions and its one of the main tools in Cardiology. It is an ultrasound test, similar to baby ultrasound during pregnancy.

In coronary artery disease, echocardiogram identifies the effect of the blocked arteries on the damaged heart muscle. It tells us how strong the heart is pumping. 

In valvular heart diseases, echocardiogram is the cornerstone examination that tells us the cause and severity of valve problems. It guides further testing, monitoring and treatment. 

A typical test takes 30-45 minutes, depending on complexity.

ECG and Exercise ECG

Electrocardiogram (ECG/EKG) records the electrical activities of the heart and gives clues towards heart health.

Exercise testing increases the oxygen demand of the heart and is more accurate than resting ECG in diagnosing coronary artery disease (blocked arteries). The test usually takes 10-15 minutes, and gets harder towards the later stages

Coronary artery disease

Coronary artery disease results from the narrowing of the internal diameter of the coronary arteries. The process is called atherosclerosis. This limits the blood supply to heart, so that oxygen supply cannot match the oxygen demand of the heart. 

When a coronary artery is gradually narrowed and partially blocked, the blood supply to that region of the heart reduces, leading to angina. This usually presents in situations when oxygen demand is high, for example, activities, when our heart rate is fast or when our blood pressure is high.

When a coronary artery suddenly blocks, there is a sudden stoppage of blood supply to parts of the heart.  When there is a lack of blood and hence oxygen to heart muscle, heart muscle dies, leading to myocardial infarction, or commonly known as heart attack.  This usually is due to atherosclerotic plaque rupture, with the formation of a thrombus on the plaque, completely occluding the coronary artery.

Atherosclerosis

Atherosclerosis is the underlying cause of coronary artery disease. This results from the build up of fatty deposits inside the arterial wall over many years. Endothelial inflammation and injury, as well as the plaque buildup with lipids, macrophages, foam cells and collagen play an important part of this process.

Atherosclerotic plaque buildup leads to the narrowing of coronary arteries, reducing coronary blood flow. The blockage of coronary arteries starves heart muscle of blood (and oxygen).

Atherosclerosis occurs in the arteries throughout the body. When atherosclerosis occurs in the head and neck arteries, it can cause stroke. When it occurs in the renal arteries, it may cause kidney failure. When it occurs in the legs, it causes peripheral vascular disease.

Heart Structure 101

Our heart is located in the centre of the chest, between the right and left lungs, under the ribcage. There are two sides to the heart (left and right). The right heart pumps blood to the lungs, whereas the left heart pumps blood to the rest of the body, including the brain, guts and the limbs. Each side of the heart is further divided into two chambers, hence four chambers in total. The atria collect blood. The ventricles contract and pump blood out.

The normal functioning of the heart muscle and valves rely on the normal functioning of the coronary arteries that provide blood supply and nutrients. The conduction system (electrical wiring system of the heart) coordinates the pumping of blood in the atria and the ventricles.

Coronary arteries branch off the aorta, which is the main artery taking blood away from the heart to the rest of the body. The coronary arteries are the first branches off the aorta. The two coronary arteries wrap around the heart like a crown, hence the name “coronary”. The left main coronary artery gives rise to the left anterior descending artery and the left circumflex artery, supplying the majority of the left ventricle; while the right coronary artery supplies the right ventricle and the underside of the heart.