According to the data from the World Health Organization, 40% of adults over 25 years old have hypertension in 2008 (1). Hypertension is very common in Hong Kong and the number of people suffering from hypertension is increasing. However, many of them don’t know they have hypertension. According to a study done by the University of Hong Kong, School of Public Health, about 1 in every 3 adults suffer from hypertension and among them about half were not aware they have hypertension. Among those who were diagnosed hypertension, about 70% received antihypertensive medications, but only 40% could control their blood pressure (2).

Often times, the cause of hypertension is unknown, this is called “primary hypertension”, which often happens after mid-life. It can be related to genetics. On the other hand, a smaller proportion of hypertension is caused by other diseases, like renal, endocrine etc., this is called “secondary hypertension”.

Hypertension is a “silent killer”, because there is usually no obvious symptom, so a lot of people don’t know they are suffering from it. If hypertension is not treated or is poor controlled, the arteries and major organs will be damaged leading to coronary heart disease, stroke, retinopathy and renal failure.

Classification of blood pressure in adults and the recommended follow up action (2)

We need to beware of a few high risk factors leading to hypertension, e.g. excessive sodium intake, obesity, sedentary lifestyle, smoking, excessive alcohol intake, stress, family history of hypertension, aging etc. Ways to prevent hypertension include:

1. Reduce sodium intake

Adults should consume less than 2g sodium per day (equivalent to about 1 tsp salt) (3)

2. Achieve a balanced diet

Follow a low fat, low sugar, low salt diet and eat more fruits and vegetables, moderate amounts of cereals, fish, lean meat, beans and milk products etc.

3. Moderate physical activity

E.g. 30-60 minutes of continuous aerobic exercise daily or 10 minutes of interval exercise 3 times daily, if you don’t have a habit of doing exercise, seek medical advice from general practitioner first (4).

4. Achieve and maintain healthy body weight.

＊Achieve Body Mass Index of 18.5-22.9 (Asian classification) (5)，waist circumference of males should be less than 90cm and females should be less than 80cm (6).

5. Regarding nutrient intake, ensure adequate potassium, calcium, magnesium etc, they are helpful in reducing blood pressure, like vegetables, fruits, low fat milk etc.

Regarding Chinese medicine, Calculus bovis is the stones in gallbladder, bile duct and hepatic duct of cattle. It is bitter in flavor, cool in nature and manifests its therapeutic actions in the liver and heart meridians. It can extinguish wind and anticonvulsive, dissolves phlegm, clears heat and has detoxification properties. Calculus bovis contains taurine, bilirubin, deoxycholic acid, cholic acid, zinc, iron, manganese etc (7). Animal studies found the antioxidant properties of Calculus bovis can decrease blood pressure (8). A randomized double-blind controlled study found taurine can increase nitric oxide thus increasing blood flow and decrease blood pressure (9). Bilirubin can decrease oxidation of vascular cells and also has anti-inflammatory effects thus help to prevent and control hypertension and coronary heart disease (8,10). Study found after rats with cerebral ischemia were fed An-Gong-Niu-Huang Wan have decreased cell injury, apoptosis, infarct area and higher neurological score, these findings indicated that An-Gong-Niu-Huang Wan has neuroprotective effects (11).

Hypertension is a “silent killer”, we should not take it lightly. Sensible diet, exercise, healthy body weight, cheerful mood, suitable medication, and regular monitoring can effectively control blood pressure.

Susan Chung, PhD

Registered Dietitian (BC Canada)

Registered Chinese Medicine Practitioner (HK)

＊Calculation of body mass index is weight (kg)/ height (m)^２

Reference:

1. World Health Organization, Global Health Observatory Data http://www.who.int/gho/ncd/risk_factors/blood_pressure_prevalence_text/en/

2. 衛生署 衞生防護中心 http://www.chp.gov.hk/tc/content/9/25/35390.html

3. World Health Organization, Guideline: Sodium intake for adults and children (2012) http://www.who.int/nutrition/publications/guidelines/sodium_intake_printversion.pdf

4. Recommendations for prescribing exercise to patients with hypertension, Doctors’ Handbook Chapter 7  http://exerciserx.cheu.gov.hk/files/DoctorsHanbook_ch7.pdf

5. WHO, Appropriate body mass index for Asian populations and its implication for policy and intervention strategies (2004) Lancet 363:157-63

6. World Health Organization, Waist circumference and waist hip ratio: Report of a WHO Expert Consultation (2011) http://apps.who.int/iris/bitstream/10665/44583/1/9789241501491_eng.pdf

7. Cia Hongjiao et al (2007), The protective effects of in vitro cultivated calculus bovis on the cerebral and myocardial cells in hypoxic mice, Journal of Huazhong University of Science and Technology 27 (6):635-38.

8.Maia AR et al (2014) Taurine supplementation reduces blood pressure and prevents endothelial dysfunction and oxidative stress in post-weaning protein-restricted rats PloS One Aug 29;9(8):e105851. doi: 10.1371/journal.pone.0105851. eCollection 2014.

9.Sun et al (2016) Taurine supplementation lowers blood pressure and improves vascular function in prehypertension. https://doi.org/10.1161/HYPERTENSIONAHA.115.06624

10. Wang et al (2015) Serum bilirubin and the risk of hypertension, Journal of Epidemiology, 44 (1): 142-52

11. Guo-Hua Wang (2014), An Gong Niu Huang Wan protects against cerebral ischemia induced apoptosis in rats: Upregulation of Bcl-2 and down regulation of Bax and caspase 3, Journal of Ethnopharmacology 154 (1): 156-62