Heavy Metal Toxicity

 

The industrial activities of the last century have caused massive increases in human exposure to heavy metals. Mercury, lead, chromium, cadmium, and arsenic have been the most common heavy metals that induced human poisonings [2]. The bioaccumulation of these heavy metals leads to diverse toxic effects to different tissues and organs, where it disrupts cellular activities such as cellular growth, damage-repairing processes, apoptosis and cell differentiation [2]. Acute or chronic poisonings may occur following exposure through the environment like water, air, and food [4].

The comparison of the mechanisms of action of heavy metals demonstrates similar pathways with essential minerals to induce toxicity in humans which includes ROS generation, compromising antioxidant defence, enzyme deactivation, and oxidative stress [2,3]. Some toxic metals including chromium, cadmium, and arsenic can cause genomic instability [3]. Induction of oxidative stress following the defects in DNA repair and DNA damage by the three metals have been considered as the cause of their carcinogenicity [6]. Several acute and chronic toxic effects of heavy metals may affect different organs and systems in the body. Gastrointestinal and kidney dysfunction, neurological disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer are examples of the complications of heavy metals toxic effects [3].

Mercury (Hg)

Elemental mercury is liquid at room temperature and can be readily evaporated to produce vapor. It is found in air, water and soil in 3 forms: elemental or metallic mercury (Hg0), inorganic mercury (Hg+, Hg2+), and organic mercury (commonly methyl or ethyl mercury) [4]. Mercury vapor is more hazardous than the liquid form of mercury. Organic mercury compounds such as methyl mercury (Me-Hg) or ethyl mercury (Et-Hg) are more hazardous than the inorganic compounds. Inhaling large amounts of mercury vapor where there are mercury spills due to container breakage can be fatal [7].

Mercury compounds have many applications in the mining process. For example the extraction of gold and industrial processes. In lamp producing factories, Hg is used in the production of fluorescent light bulbs. Me-Hg and Et-Hg were used as fungicides to protect agricultural crops against infections [4]. In addition, Hg had been used in the medicinal industry, however it had been replaced with safer pharmaceutical drugs to prevent hazardous events [7]. Some examples are the diuretics chlormerodrin, merbaphen, and mercurophylline and phenylmercury nitrate (disinfectant) [1].

Lead (Pb)

Lead is a catastrophic environmental pollutant which has high toxic effects to various body organs. Even though Pb can be absorbed from the skin, it is mostly absorbed from respiratory and digestive systems [5]. Pb is highly toxic which has adverse effects on the neurological, biological, and cognitive functions in the bodies. Chronic Pb exposure can lead to various disorders in the nervous system, respiratory tract, urinary, and cardiovascular system due to immune-modulation, oxidative, and inflammatory mechanisms [10]. Furthermore, Pb could disrupt the balance of the free-radical and antioxidant activities and promote chronic inflammation in many organs. Exposure to Pb can alter physiological functions and leads to different chronic diseases in later life [5].

Anemia may develop with Pb poisoning via the inhibition of ferrochelatase and δ-aminolevulinic acid dehydratase (ALAD), two enzymes involved in heme biosynthesis [4]. Several antioxidant molecules may have alterations due to Pb exposure and subsequent oxidative stress. Pb has high affinity to the antioxidant molecules which it competes to bind to the antioxidative enzymes and thus decreases the ability of antioxidant defense [4]. The antioxidant functions to detoxifying free radicals could be affected due to Pb exposure. Pb can promote oxidative damage in different organs via direct effect on membrane lipid peroxidation and reducing antioxidant parameters [1].

Chromium (Cr)

Chromium is commonly found in the earth’s crust and seawater. It is a naturally occurring heavy metal in industrial processes. Cr has multiple oxidation states ranging from −2 to + 6, in which the trivalent and hexavalent forms are the most stable forms. Cr (VI) is related to a series of diseases and pathologies while Cr (III) is required in trace amounts for natural lipid and protein metabolism and also as a cofactor for insulin action [3]. Based on the International Agency for Research on Cancer (IARC) report (2018), hexavalent chromium has been classified as a group I occupational carcinogen [6]. The primary route of exposure for non-occupational human populations occurs via ingestion of chromium containing food and water or dermal contact with products containing chromium [6]. Moreover, refractory, metallurgic, and chemical industries release a large amount of Cr into soil, ground water, and air which put humans, animals, and marine life at risk [6]. Cr can cause various diseases via bioaccumulation in the human body which includes dermal, renal, neurological, and GI diseases to the promotion of tumor growth including in different organs [10].

Cadmium (Cd)

Cadmium occurs naturally in soil and minerals such as sulfide, sulfate, carbonate, chloride, and hydroxide salts as well as in water. High Cd level in water, air, and soil is linked with industrial activities which could be a significant human exposure to Cd, thus the ingestion of Cd contaminated food is one of the major exposure [10]. Moreover, cigarette smoking is also connected as one of the factors of Cd exposure, which is capable of elevating Cd concentrations in blood and urine [3]. Presence of Cd in contaminated water could disturb the necessary mechanisms in the body, potentially resulting in acute or chronic diseases [2,3]. Cd is classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans (Group 1) [6]. Occupational exposure to Cd may occur in alloy, battery, and glass production and in electroplating industries. Due to the importance of the subject, Cd level in the air is routinely monitored in some countries [2]. Unlike low GI absorption, Cd is more efficiently taken from the lungs via inhalation of industrial dust. Acute or chronic inhalation of Cd in industrial areas might lead to renal tubular dysfunction and lung injuries. Cd blood concentration in smokers is almost twice higher than that of non-smokers [2].

Arsenic (As)

Arsenic as a harmful heavy metal is one of the main risk factors for public health. Sources of As exposure are occupational or via the contaminated food and water. It has a long history of use, either as a metalloid substance or as a medicinal product [7]. As is present as a contaminant in food, water, and the environment. Arsenic exists in the forms of metalloid (As0), inorganic (As3+ and As5+), organic, and arsine (AsH3). The order of increasing toxicity of As compounds is defined as organic arsenicals < As0 < inorganic species (As5+ < As3+) < arsine [8,9]. Primary As absorption is from the small intestine, followed by skin contact and inhalation. Following distribution to many tissues and organs in the body including the lungs, heart, kidneys, liver, muscles, and neural tissue, As is metabolized to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in which the latter is the predominant form in the urinary excretion of As [8].

Acute and chronic As toxicity is related to the dysfunctions of numerous vital enzymes. Similar to the other heavy metals, As can inhibit sulfhydryl groups containing enzymes which leads to their dysfunction [9]. Moreover, As inhibits the pyruvate dehydrogenase by binding to the lipoic acid moiety of the enzyme. Pyruvate dehydrogenase inactivation can block the Krebs cycle and inhibits oxidative phosphorylation. As a result, ATP production decreases, resulting in cell damage [7]. Furthermore, the damage of capillary endothelium by As increases vascular permeability, leading to vasodilation and circulatory collapse [7].

To avoid heavy metal exposure:

1. Always wash the foods before consumption in order to remove the chemicals such as pesticides and fungicides.
2. Check the functionality of the water filter regularly.
3. Eat a variety of nutritious foods.
4. Consume supplements that help to remove heavy metals from the body
5. Take wholesome and natural foods that help to remove heavy metals from the body such as cilantro, chlorella, garlic, lemon water, etc.

 

Angel, Nutritionist
ANNA HOO CLINIC

 

References:

1. Dadpour, B., et al. (2016). Clinical and laboratory findings of lead hepatotoxicity in the workers of a car battery manufacturing factory. Iranian J. Toxicol. 10 (2), 1–6. 

2. Engwa, G. A. et al. (2019) ‘10.5772@Intechopen.82511.Pdf’, Mechanism and Health Effects of Heavy Metal Toxicity in Humans, p. 23. 

3. Gorini, F., et al. (2014). The role of heavy metal pollution in neurobehavioral disorders: a focus on autism. Rev. J. Autism Dev. Disord. 1 (4), 354–372. doi:10.1007/s40489-014-0028-3 

4. Kianoush, S., et al. (2015). Recent advances in the clinical management of lead poisoning. Acta Med. Iran 53, 327–336. 

5. Kim, T. H., et al. (2020). Exposure assessment and safe intake guidelines for heavy metals in consumed fishery products in the Republic of Korea. Environ. Sci. Pollut. Res. Int., 27, 33042–33051. doi:10.1007/s11356-020-09624-0

6. Koedrith, P., et al. (2013). Toxicogenomic approaches for understanding molecular mechanisms of heavy metal mutagenicity and carcinogenicity. Int. J. Hyg. Environ. Health 216 (5), 587–598. doi:10.1016/j.ijheh.2013.02.010 

7. Lee, M.-R., et al. (2017). Blood mercury concentrations are associated with decline in liver function in an elderly population: a panel study. Environ. Health 16 (1), 17. doi:10.1186/s12940-017-0228-2 

8. ​​Li, L., and Chen, F. (2016). Oxidative stress, epigenetics, and cancer stem cells in arsenic carcinogenesis and prevention. Curr. Pharmacol. Rep. 2 (2), 57–63. doi:10.1007/s40495-016-0049-y 

9. Liaw, J., et al. (2008). Increased childhood liver cancer mortality and arsenic in drinking water in northern Chile. Cancer Epidemiol. Biomarkers Prev. 17 (8), 1982–1987. doi:10.1158/1055-9965.epi-07-2816

10. Lin, X., et al. (2018). Connecting gastrointestinal cancer risk to cadmium and lead exposure in the Chaoshan population of Southeast China. Environ. Sci. Pollut. Res. Int. 25 (18), 17611–17619. doi:10.1007/s11356-018-1914-5

 

Sugar-Free – Is there more behind the label?

It’s no surprise that we automatically reach for the “sugar-free” food or beverage on the shelf in a bid to be healthier. But before that, read on to understand the true meaning behind the term “sugar-free” and learn to make informed choices.

What are sugar substitutes?

Any form of sweetener that is used to replace table sugar (sucrose) can be termed as a sugar substitute. These sugar substitutes can be classified into two categories – natural & artificial sweetener.

·       Natural sweeteners

These sugar substitutes are often promoted as healthier options, but often undergo processing and refining as well. Common natural sweeteners include:

- Coconut sugar

- Honey

- Molasses

- Maple syrup

- Palm sugar

While these natural sweeteners are touted as healthy due to the additional nutrient content, they contain the same amount of calories and are absorbed the same way as regular sugar, hence raising blood sugar levels. Hence. intake of these sweeteners should be considered the same as table sugar.

·      Low-calorie sweeteners

These sugar substitutes are usually derived from plants.  While the sweetness receptors on our taste buds recognize these sweeteners as sweet-tasting, they are not broken down and are absorbed by our body differently as compared to sugar, due to the different structure. Hence, these sweeteners provide a sweet taste with much less calories, and without negative consequences on blood sugar levels.

While these sweeteners do contain calories, they are usually labelled as “zero-calorie” because they provide intense sweetness with usage at just a small amount of negligible calories.

Popular non-nutritive sweeteners include:

- Erythritol

- Allulose

- Monk fruit sweetener

- Xylitol

- Stevia 

While low-calorie sugar substitutes are beneficial for weight management and diabetics as they are low in calories and do not raise blood sugar levels, studies have raised possible health concerns:

1.     Increased Appetite & Cravings for Sugar

Regularly consuming sweetened food products, even if they have been substituted with sugar substitute, may increase appetite and cravings for sweet foods in general. Increased consumption of these foods may also displace intake of natural foods, which are lower in calories and nutrient-dense. In the long run, frequent intake can lead to weight gain and malnutrition.

2.     Gut Health

Maintain a healthy gut by having the right balance of good and bad bacteria composition is key towards optimal physical and mental health. The composition of gut bacteria varies by individual and is affected by lifestyle habits. Sugar substitutes have been found to reduce the composition of beneficial bacteria. In some studies, sugar substitutes also disrupted the gut bacteria balance and caused poorer blood sugar control among consumers.

Moderation and Shopping Smart is Key:

Sugar substitutes are beneficial if you are trying to gradually reduce sugar intake and manage weight. However, it is important to generally reduce sweetness levels of foods and minimize consumption of both sugar and sugar substitutes. Instead, whole foods such as fruits, vegetables, grains and protein should be the basis of your diet as well, rather than processed foods.

At the same time, read food labels carefully and understand the meaning behind it:

- No sugar or sugar-free: The product does not contain sugar, but may contain natural or artificial sweeteners and sugar alcohol.

- No added sugar: No extra sugar was added during processing. However, the original source might have contained sugar (for example: fructose in fruit juice). Sugar substitutes may have also been added.

 

Zuanne, Nutritionist
Anna Hoo Clinic

Reference:

1.      Ma, J., Bellon, M., Wishart, J. M., Young, R., Blackshaw, L. A., Jones, K. L., ... & Rayner, C. K. (2009). Effect of the artificial sweetener, sucralose, on gastric emptying and incretin hormone release in healthy subjects. American Journal of Physiology-Gastrointestinal and Liver Physiology, 296(4), G735-G739.

2.      Ford, H. E., Peters, V., Martin, N. M., Sleeth, M. L., Ghatei, M. A., Frost, G. S., & Bloom, S. R. (2011). Effects of oral ingestion of sucralose on gut hormone response and appetite in healthy normal-weight subjects. European journal of clinical nutrition, 65(4), 508-513.

3.      Yang, Q. (2010). Gain weight by “going diet?” Artificial sweeteners and the neurobiology of sugar cravings: Neuroscience 2010. The Yale journal of biology and medicine, 83(2), 101.

4.      Suez, J., Korem, T., Zeevi, D., Zilberman-Schapira, G., Thaiss, C. A., Maza, O., ... & Elinav, E. (2014). Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature, 514(7521), 181-186.

 

 

Probiotics & Prebiotics – What’s the Difference?

 

Probiotics and prebiotics have been the center of discussion for years now when we talk about a healthy digestive system. But before you jump onto the bandwagon of including probiotics or prebiotics into your regime, read on to learn more about the different roles of these two.

Having a healthy gut not only ensures a healthy digestive system but impacts physical and mental health, as many important health functions occur in the gut. The complex community of bacteria in the gut manufactures vitamins and produces short chain fatty acids which strengthen the immune system.

One key indicator of having a healthy gut is through having the right balance of good and bad bacteria. This balance is easily disturbed as the gut is highly sensitive to our lifestyle habits such as chronic stress, poor diet, long term medication usage, tobacco and alcohol consumption.

This is where probiotics and prebiotics come in handy.

1.     Probiotics

Probiotics refer to the group of “good” bacteria that provide health benefits when ingested. The most common probiotic bacteria that have been widely studied are Lactobacillus and Bifidobacterium.

Source of Probiotics

• Fermented foods such as yogurt, tempeh, kimchi, sauerkraut.
• Supplement form

Benefits

Different probiotics have been found to address different health conditions, which is why most supplements combine a few species in a product. At the same time, it is essential to select the right probiotic that addresses your health concern.

• Studies have found the beneficial effects of probiotics including:
• Alleviating digestive disorders including bloating, constipation, diarrhea and gas
• Reducing inflammation – the hallmark of diseases
• Enhance immune function to protect against infections
• Reduce symptoms of anxiety and depression
• Aid in weight management

 

2.     Prebiotics

On the other hand, prebiotics refer to a group of carbohydrates that the human body cannot digest. However, these non-digestible carbohydrates serve as a food source for the gut’s healthy bacteria. Prebiotics selectively stimulate the growth of good bacteria in the gut, especially the Lactobacilli and Bifidobacteria group, which in turn provide the health benefits associated with these bacteria.

Source of Prebiotics

• Fruits, vegetables and whole grains such as apples, bananas, berries, legumes, peas, flaxseed, green vegetables. 
• Added to food products especially baby formula and yogurt. These are usually labelled as “fortified with galactooligosaccharides, fructooligosaccharides, oligofructose, chicory fiber, or inulin”. 
• Supplement form

Benefits

There are plenty of ongoing research to understand the full effects of prebiotics on gut health. Prebiotics have been shown to:

• Support growth of probiotics
• Improve calcium absorption
• Fermented by gut bacteria to product short-chain fatty acids, which improves gut integrity and prevents Leaky Gut syndrome, which leads to inflammation in the body.

In summary, probiotics themselves are the “good” live bacteria, while prebiotics are the foods for these bacteria. Hence, introducing probiotics and prebiotics can help ensure that you have the right balance of microflora in the gut for optimal health.

To introduce probiotics and prebiotics, practise a balanced diet that is abundant with a variety of high fiber fruits and vegetables. Fermented foods are a great option as well. At the same time, limit foods that are high in sugar and are processed, as these stimulate growth of bad bacteria in the gut, which ultimately affects the balance, regardless of how much probiotics you’re taking,

For supplements, select a supplement that contains both probiotics and prebiotics. However, it is best to speak to your healthcare provider to guide you in selecting the right supplement that addresses your needs as not all probiotics work the same way, and certain forms may not be suitable for those who are lactose intolerant or with yeast (Candida) overgrowth.

 

Reference

 

1.      Bischoff, S. C. (2011). 'Gut health': a new objective in medicine? BMC medicine, 9(1), 1-14.

2.      Quigley, E. M. (2013). Gut bacteria in health and disease. Gastroenterology & hepatology, 9(9), 560.

3.      Whisner, C. M., & Castillo, L. F. (2018). Prebiotics, bone and mineral metabolism. Calcified Tissue International, 102(4), 443-479.

4.      Slavin, J. (2013). Fiber and prebiotics: mechanisms and health benefits. Nutrients, 5(4), 1417-1435.

5.      Esgalhado, M., Kemp, J. A., Damasceno, N. R., Fouque, D., & Mafra, D. (2017). Short-chain fatty acids: A link between prebiotics and microbiota in chronic kidney disease. Future microbiology, 12(15), 1413-1425.

 

 

By Nutritionist 

Zuanne
Anna Hoo Clinic

八个提高免疫力的建议

 

传染疾病流行，免疫系统为我们抵御各种病毒、细菌等微生物的感染。不管什么病毒袭来，强大的免疫系统便是人体抵抗病毒感染的第一道防线。

那么，什么是免疫力？怎样增强免疫力呢？

免疫力是指人体免疫系统抵抗有害微生物和疾病的能力。我们的免疫系统极为复杂，包括免疫器官、免疫细胞、以及免疫分子等。大家都知道增强免疫力就可以提高我们的抵抗力，听起来很有道理，但是事实上却不容易。

首先，免疫系统不是一个简单的器官,不仅组织庞大、成员众多，而是一个极其复杂精密又相互调节的系统。其次，对于免疫反应的复杂性和相互作用，我们还有许多未知的东西，免疫细胞并不是越多越好，免疫反应也不是越强越好。免疫系统要发挥良好的作用，需要系统各部分之间的数量和功能上的平衡与和谐，而不仅仅是加强某一项。

提高免疫力没有神药，保持身体的整体健康是根本。保障有强力健康的免疫系统，除了我们无法控制的遗传因素之外，最重要的是坚持健康的生活方式。尽量避免不健康的环境和习惯，这样身体的每个部分包括免疫系统的功能自然会更好。

近日，哈佛大学的专家们给出了提高免疫力的八个建议。

01 营养均衡的健康饮食 

就像任何战斗部队都需要供给一样，免疫系统作为身体的自卫军需要优质而有规律的营养供应。均衡而健康营养的饮食很重要。科学家们早就意识到生活贫困和营养不良的人更容易得传染病。老年人的饮食营养和免疫力低下之间也存在着相关性。老年人往往吃得少，饮食多样性也不够。许多研究发现，与年轻人相比，老年人不仅更容易患上传染病而且死亡率最高。即便在富裕国家，一种被称为“微量营养素营养不良”的情况也普遍存在。“微量营养素营养不良”是指缺乏某些必需的维生素和微量矿物质。这些微量营养素必须从饮食或食物补充剂中获得。对于食物摄入不足或者缺乏某些营养素的人群，食物补充剂可能会有帮助。

02 保持健康的体重

如何知道你的体重是否在健康范围？测量身体质量指数Body Mass Index (BMI) 简单易行。BMI的计算方法是将成人的体重(以公斤) 除以身高 (以米为单位)的平方。亚洲人的评估标准是：健康的BMI范围为18.5至22.9；23.0-27.4 属于超重；超过27.5属于肥胖。研究显示拥有健康的BMI，尤其是在理想范围内的人，死于疾病的风险较低。

03 经常锻炼

 

运动改善心血管健康，降低血压，帮助控制体重，并预防各种疾病。但这是否有助于自然增强免疫系统并维系免疫系统的健康呢？就像健康饮食一样，运动可以促进整体健康，从而促进免疫系统的健康。它还可以直接通过促进血液循环，使免疫细胞和免疫因子更流畅地达到全身各处，更有效地发挥其保护作用。

04 保证充足的睡眠

睡眠是身体休息并恢复生机的时候。虽然每个人需要的睡眠时间不一样，但通常都需要7-9个小时的优质睡眠。少熬夜早休息，是增强人体免疫功能很重要的生活习惯。

05 减轻压力

现代医学已认识到身心之间的紧密联系。各种各样的疾病，从胃部不适到心脏病，都可能与情绪或压力有关。科学家正积极研究压力与免疫功能之间的关系，尤其是长期压力状态对人体免疫功能的影响。适当缓解压力有助于整体健康，也会助于促进免疫系统的功能。

06 少吸烟，少喝酒

吸烟不仅增加患癌风险，还会损害人体免疫系统。对吸烟的人群来说，如果希望健康，最需要做的事就是戒烟。

07 坚持良好的卫生习惯

保持良好的卫生习惯包括经常洗手、不吃生肉、分餐制、用公筷等，以避免微生物感染。       

08 按时接种疫苗

按时接种疫苗。疫苗可激发免疫系统，在病毒感染之前帮助我们的身体做好准备。

 

结论：

防疫期间，我们得靠自己提升自身免疫力，对自己的健康自律。以上的专家建议供大家做个参考。与其服用各种神药，通过均衡的饮食和健康的生活方式自然增强免疫系统会更好。愿大家齐心抗疫，早日战胜病毒！

 

Anna Hoo Clinic

Lara 营养师

 

文献参考：

https://www.health.harvard.edu/staying-healthy/how-to-boost-your-immune-system