Heart Disease – Does green tea lower heart disease risk?

All right, this green tea article has been hanging over my head for at least a month now. I just couldn’t get motivated to wade through all the research to determine if yes, this is an effective way to lower cholesterol and prevent heart disease, or no, it’s just a lot of hype.

Well, I sat down and sorted it all out today and here’s what I found.

Health Claim

The proposed health claim for green tea is that drinking at least 5 fluid ounces as a source of catechins may reduce risk factors associated with cardiovascular disease.

What are catchins?

Green tea contains catechins, which are a type of flavenoid with antioxidant properties. Antioxidants slow the oxidation process. The oxidation of LDL molecules is what results in plaque formation. Therefore, increasing antioxidant intake should slow oxidation of LDL, resulting in less arterial plaque formation.

Also, when molecules are oxidized, free radicals are released that damage cells. These free radicals can increase inflammatory issues associated with cardiovascular disease.

How flavenoids work

The body recognizes flavenoids as foreign particles and works to eliminate them from the body. Flavenoids themselves do not act as an antioxidant and they are poorly absorbed by the body. However, the proposed benefit of extra flavenoids is that as the body eliminates the unwanted flavenoids, damaging free radicals are also eliminated.

Tea production

The various types of tea are produced differently. The leaves of oolong tea and black tea are allowed to oxidize (enzymes in the tea change catechins to larger molecules). Green tea is not oxidized, but produced by steaming fresh-cut leaves whereby enzymes are inactivated and little oxidation occurs. The least processed tea is white tea, which contains the highest levels of catechins. Green tea contains the second highest catechin level, approximately 125 mg catechins per serving (or ~25% dry weight of fresh tea leaves).

Here’s a little breakdown on tea oxidation:
Black tea – Highest oxidation; also, highest caffeine content and strongest flavor; 90% of all tea served in the West is black tea
Oolong tea – 10-70% oxidized
Green tea – Low oxidation
White tea – Minimal oxidation; Uncured, unfermented; Lower caffeine content that other teas

FDA Review

In 2005, the FDA did not approve the health claim for green tea, because the link between green tea and reduced cardiovascular disease risk was too weak and more conclusive evidence was needed.

Recent Research

This past June, 2008, a study was published that links green tea to reduced flow-mediated dilation of brachial arteries (major blood vessels in the upper arms). Flow-mediated dilation is related to coronary endothelial function and is an indicator for cardiovascular disease risk. Increased dilation is good. It means the heart has to do less work to move blood throughout circulation. (The endothelium is the inner layer of an artery, which blood flows against.)

This was a study of 14 healthy individuals that consumed 6 grams of green tea, followed by a measure of flow-mediated dilation. The results showed an increased flow-mediated dilation with tea (peak at 30 minutes post consumption). There was no change to antioxidant status after consumption. It’s proposed that the improved flow-mediated dilation is how green tea reduces cardiovascular disease risk.

The Hype

I came across multiple articles with headlines screaming “Green Tea Protects Against Heart Disease” since this study was published in June. I think there is significant research that still needs to be completed before it can be determined for sure how tea works to prevent heart disease. A study of 14 individuals is a small study.

Drinking 6 grams of green tea, would equal about three – 6 ounce cups of green tea each day. (Based on making 1 six ounce cup of tea with 1 teaspoon or 2.25 grams of green tea.) However, the study results are based on consuming 6 grams of tea in one setting followed by improved flow-mediated dilation at peak levels 30 minutes after consumption. How likely is it for you to drink three cups of tea quickly, back-to-back to reproduce the short-term benefit shown in this study?

To me, that is not a very effective way to reduce heart disease risk. But, I will say that if you like green tea – drink it. Many studies are showing that green tea is beneficial to heart disease. The what, how, and how much is yet to be determined. Who knows what future studies will find?!

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All the best,
Lisa Nelson RD

Heart Disease – Link between Temperament, Personality, and Heart Disease Risk

Lisa Nelson RD: What role does temperament/personality play in a person’s heart disease risk?

Dr. Shelby-Lane: Temperament and personality have a definite effect on blood pressure and on heart disease. This is a great question and it has been studied by the experts, as you will note in the following excerpts. Heart disease consists of congenital abnormalities, arrhthymias, lipid abnormalities acquired and congenital, functional and physiologic problems, risk factors such as diabetes and metabolic syndrome, structural disease and valvular problems, heart failure, acquired disease such as coronary artery disuse, and infectious diseases along with diseases related to blood vessel structure. Again, anxiety, stress, and stress related disorders can have an effect on major hormones, heart rate and heart health and heart disease. Nutritional abnormalities can also affect heart performance.

New research suggests that people who suffer from panic attacks are at increased risk of developing heart disease.

Why people who suffer from panic attacks should be at increased risk of developing heart disease is unclear. According to the study, authors put forward several theories, one being that panic disorders might trigger nervous system changes which could promote the clogging of arteries. Another theory is that people may have been misdiagnosed as having panic attacks when they actually have coronary heart disease. “Clinicians should be vigilant for this possibility when diagnosing and treating people presenting with symptoms of panic,” said Dr Walters.

Study results have shown that people with depression are at increased risk of heart attack and heart failure because they are less likely to be active.

Scientists have known for some years that people who are depressed are at increased risk of heart attack and other cardiac events, however the reason why this should be has remained unclear. However, according to results of a study by Mary A Wooley and colleagues, the increased risk is due to behavioral factors.

The researchers analyzed data obtained from 1,017 people with heart disease, 199 of which had symptoms of depression. Results showed that 10% of depressed participants had a cardiac event (e.g. heart attack, heart failure, stroke, transient ischemic attack) during the study period, compared to just 6.7% of non-depressed participants, meaning that depressed participants were 50% more likely to have a cardiac event. However, results also showed that depressed participants were more likely to smoke, were less likely to take their medications as prescribed, and were less physically active. After the researchers factored these behaviors into their calculations the risk of a cardiac event in depressed participants was similar to that in non-depressed participants.

All the best,
Lisa Nelson RD
Be Heart Healthy and Lose Weight

High Blood Pressure and Magnesium

Magnesium is not a mineral that tops discussions very often; however, magnesium is critical to over 300 bodily functions.  Magnesium maintains normal muscle and nerve function, helps regulate blood sugar levels, promotes normal blood pressure and heart rhythm, maintains bone strength, and supports a healthy immune system. 

Many people consume a diet low in magnesium receiving less than two-thirds of the recommended dietary allowance. Good magnesium sources include whole grains, spinach, broccoli, squash, beans, popcorn, nuts, pork, and seeds. Fair sources of magnesium include dairy products, chocolate, and meats.

 

A magnesium deficiency takes a long time to develop. Magnesium deficiency symptoms include irregular heartbeat, weakness, fatigue, numbness, muscle pain, disorientation, and seizures. Conditions related to increased risk for magnesium deficiency include alcoholism, poorly controlled diabetes, intestinal disorders (Crohn’s disease), and intake of certain medications (diuretics). Sup-optimal levels of magnesium intake have been linked with diabetes, hypertension, osteoporosis, and pregnancy discomfort.

 

Diabetes

 

When someone has type II diabetes they are making adequate insulin levels. The problem with type II diabetes is that the cells do not recognize the insulin. When cells do not recognize insulin they do not let sugar from the blood enter the cell and blood sugar levels remain elevated. This leads to sugar spilling over into the urine, organ damage, and other complications. Magnesium is a factor in this because it’s the “key” that opens the door for insulin to get into the cell.  If magnesium levels are low there are no keys to open the door and insulin is unable to do its job resulting in continued high blood sugar levels.  When diabetes is poorly controlled the loss of magnesium in the urine is even greater.

 

Hypertension

 

Blood levels of potassium, calcium, and magnesium are closely connected and all influence blood pressure. Studies have linked low magnesium levels with elevated blood pressure. As an aside, if you have ever been told to eat a banana by your doctor, you should also increase your magnesium intake. FYI – Bananas are not the best source of potassium – potatoes are!

 

Osteoporosis

 

Magnesium is a major component of the matrix (middle) of bones. Low magnesium levels cause fragile bones that are less flexible and have a slower recovery rate if injured.

 

Pregnancy

 

Adequate levels of magnesium are related to decreased leg cramps during pregnancy. A magnesium deficiency is also a risk factor for gestational diabetes.

 

Recommended Dietary Allowances (RDA) for Magnesium:

 

Men 350 mg per day

Women 280 mg
Pregnancy 300 mg
Lactation 355 mg first 6 months; 340 mg next 6 months

 

You do NOT want to take megadoses of magnesium – more is not better in this case.  You just want enough to meet the RDA. If you feel your intake of magnesium from foods is low, taking a basic multivitamin is a simple way to ensure you meet your needs. Read the multivitamin label carefully because not all multivitamins include magnesium. Always check with your doctor before altering your medications or supplements.

 

Bottom Line:

 

Magnesium may not be an exciting mineral, but it is critical.  Ensure you are eating adequate sources of magnesium rich foods and/or consider a supplement to promote optimum health.

 

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Posted in heart health, high blood pressure | Tagged: deficiency, Heart Disease, heart health, high blood pressure, hypertension, magnesium | 1 Comment »