Most of us are aware that high cholesterol level can lead to cardiovascular diseases (CVD – disease of the heart and blood vessels). But do you know that there is another compound in our blood that similarly can cause these diseases called homocysteine? Homocysteine is produced by our body through the breakdown of methionine obtained from consuming protein sources such as meat and poultry. Our body produces homocysteine to further create cysteine, an essential amino acid for nail, skin, hair and for production of collagen.
大多数人都知道高胆固醇水平会导致心血管疾病（CVD – 心脏和血管疾病）。但是您知道我们血液中还有另一种称为同型半胱氨酸，同样也会导致这些疾病的化合物吗？同型半胱氨酸是由我们的身体通过分解蛋氨酸而产生的。蛋氨酸是从肉类和家禽等蛋白质来源中获得的。我们的身体会产生同型半胱氨酸以进一步产生半胱氨酸。半胱氨酸是指甲、皮肤、头发和胶原蛋白生成所需的氨基酸。
However, too much homocysteine in our blood can cause damage to the walls of our blood vessels and can increase risk of blood clots formation. This damage can weaken the blood vessels, while the blood clots can clog your vessels, which increase the risk of having heart attack, heart diseases, stroke, and other vascular diseases.
然而，血液中过多的同型半胱氨酸会对我们的血管壁造成损害，并且会增加血栓的风险。这种损伤会削弱血管，而血栓会堵塞血管，从而增加患上心脏病、中风和其他血管疾病的风险。
There are various reasons as to how one can have high homocysteine level. Among them include high intake of animal proteins, chronic renal failure, hypothyroidism, malignancies, some chemotherapy treatment, oral contraceptive use, smoking and old age. Rarely, one can have elevated homocysteine level due to inherited or congenital diseases such as homocystinuria and MTHFR gene mutation.
一个人如何具有高同型半胱氨酸水平的原因有多种。其中包括大量摄入动物蛋白、慢性肾功能衰竭、甲状腺机能减退、恶性肿瘤、化疗、口服避孕药的使用、吸烟和年老。极少数情况下，由于遗传或先天性疾病（例如同型半胱氨酸尿症和 MTHFR 基因突变），同型半胱氨酸水平会升高。
Meanwhile, the most common factor of elevated homocysteine level is the deficiency of vitamin B6, B9 and B12. This is as our body uses these vitamins to break down the homocysteine into other components. Research also supported that the supplementation of these vitamins can reduce the level of homocysteine in our blood.
与此同时，同型半胱氨酸水平升高最常见的因素是缺乏维生素B6、B9和B12。这是因为我们的身体需要这些维生素将同型半胱氨酸分解成其他成分。研究还显示补充这些维生素可以降低血液中同型半胱氨酸的水平。
Therefore, adequate intake of vitamin B6, B9 and B12 is crucial. Here are some dietary sources of these nutrients:
因此，摄入充足的维生素B6、B9和B12至关重要。以下是这些营养素的一些饮食来源：
- Vitamin B6 (pyridoxine) / 维生素B6（吡哆醇）:
- Animal sources: Meat (including poultry, pork, beef and etcetera), fish, fortified food
动物来源：肉类（包括家禽、猪肉、牛肉等）、鱼类、强化食品
- Plant sources: Starchy vegetables (such as potatoes), beans, legumes, nuts, some fruits (including banana, plantain, avocado and dried fruit such as raisin, date, and prune), fortified food
植物来源：淀粉类蔬菜（如土豆）、豆类、坚果、水果包括香蕉、车前草、鳄梨和干果（葡萄干、枣和李子）、强化食品
- Vitamin B9 (folate) / 维生素B9（叶酸）:
- Animal sources: Liver, seafood, eggs, dairy products (including cheese and yogurt), fortified food
动物来源：肝脏、海鲜、鸡蛋、乳制品（包括乳酪和酸奶）、强化食品
- Plant sources: Vegetables (Brussel sprouts, broccoli and green leafy vegetables such as kale, spinach and cabbage), peas, beans, lentils, nuts, fruits and fruit juices, wholegrain, fortified food
植物来源：蔬菜（球芽甘蓝、西兰花和绿叶蔬菜如羽衣甘蓝、菠菜和卷心菜）、豌豆、豆类、扁豆、坚果、水果和果汁、全麦、强化食品
- Vitamin B12 (cobalamin) / 维生素B12（钴胺素）:
- Animal sources: Meat (including poultry, beef and etcetera), fish, dairy products (including cheese and yogurt), eggs, fortified food
动物来源：肉类（包括家禽、猪肉、牛肉等）、鱼类、乳制品（乳酪和酸奶）、鸡蛋、强化食品
- Plant sources: Nutritional yeast, seaweed, some mushrooms (dried shiitake, black trumpet, porcini), fortified food
植物来源：营养酵母、海藻蘑菇（干香菇、黑喇叭、牛肝菌）、强化食品
While consumption of vitamin B6, B12 and B9 can indeed reduce the homocysteine level, research also states that this reduction does not directly decrease the risk of developing CVD. Therefore, it is also important that the main risk factors of CVD, as stated below, be avoided:
虽然摄入维生素 B6、B12 和 B9 确实可以降低同型半胱氨酸水平，但研究还指出，这种降低并不能直接降低患上CVD的风险。因此，避免以下患上CVD的主要危险因素很重要：
- Unhealthy diet (high saturated and trans-fat, high sodium, high added sugar, low fibre) / 不健康的饮食（高饱和脂肪和反式脂肪、高钠、高添加糖、低纤维）
- Being overweight and obese / 超重和肥胖
- Smoking / 抽烟
- Excessive alcohol intake / 过量饮酒
- Physical inactivity / 缺乏运动
Theoretically, consumption of methionine (through intake of protein sources) excessively can increase the level of homocysteine. However, except for the cases of congenital and genetic mutations (in which restriction of methionine is crucial), restriction of methionine can also lead to protein inadequacy as most protein sources contain methionine. Furthermore, a lot of protein sources also serve as the source of vitamin B6, B9 and B12. Therefore, moderation is key.
从理论上讲，过量摄入蛋氨酸（通过摄入蛋白质来源）会增加同型半胱氨酸的水平。然而，除了先天性和基因突变的情况（其中限制蛋氨酸至关重要），限制蛋氨酸也会导致蛋白质不足，因为大多数蛋白质来源都含有蛋氨酸。此外，许多蛋白质来源也是维生素 B6、B9 和 B12 的来源。因此，适度是关键。
What should be avoided are protein sources high in saturated fat and trans-fat (mainly from animal sources such as poultry skin, fatty meat, processed meat and full cream dairy products), and integration of plant protein (cholesterol-free, low in saturated fat, high in fibre) as part of our dietary protein source.
因此，我们应该避免的是高饱和脂肪和反式脂肪的蛋白质来源（主要来自动物来源，如家禽皮、肥肉、加工肉类和全脂乳制品），以及植物蛋白的整合（不含胆固醇、低饱和脂肪、高纤维）作为我们膳食蛋白质来源的一部分。
