Effectiveness of Soy in reducing the risk of hyperlipidaemia

This Research Article has been supervised by Nutritionist/Food Expert Anum Nazir).She is Lecturer in School of Nutritional sciences At University of Faisalabad).

Researcher And Writer

 Faiza Zahid 

Supervised By Anum  Nazir 

Department of Nutritional Sciences

University Of Faisalabad,Pakistan

Topic;Effectiveness of Soy in reducing the risk of hyperlipidaemia.

Abstract

 

Soy is found to have an inverse relationship with its consumption and prevalence of heart diseases. It helps to lower LaDL cholesterol and raise HDL cholesterol. Soy lowers total cholesterol of blood and reduces the risk of hyperlipidaemia and many heart conditions associated with it. It has family of six compounds that provides soy anti cancer properties. Soy is beneficial in improving bone health, prevent oral problems, help control diabetes, important for renal health. However, it’s negative outcomes can be allergic response due to its consumption and poor digestion when consumed raw. Soy reduces risk of many hormone dependent cancer such as breast and prostate cancer due to the structural similarity of isoflavones to Estrogen and testosterone respectively that bind to their receptors and reduces effect of these hormones. Soy products delays aging as well. It is also suspected that soy can induce chromosomal changes that can lead to cancer. Data supporting this view is though limited.

 

Introduction

 

Lean body mass (muscle mass) should be higher than fats in the body to reduce the risk of cardiovascular diseases (CVDs). For this net muscle protein balance must be positive which means rate of protein synthesis must be higher than breakdown. Muscle balance can be maintained by ensuring appropriate dietary intake of amino acids as well as physical activity. Soy (plant based) and whey (animal based) are both good sources of high quality protein. These are widely used as supplements in sports world. Both proteins are easy to digest and have similar absorption mechanisms. However, it is suggested that soy is effective in reducing the risk of CVDs while whey is not. Soy has an ability to improve lipid profile. Soy’s non-essential amino acid content favours post-prandial production of glucagon, which, as opposed to insulin, down-regulates lipogenic enzymes and lowers cholesterol synthesis. It also have many other bio active components with cholesterol lowering properties. The plant-based protein’s potential

 

to lower blood lipids and reduce oxidative stress may provide a simple, cost-effective means of reducing cardiovascular disease risk. (DeNysschen et ol., 2009)

 

Increased levels of lipids (hyperlipidaemia: cholesterol and triglycerides) in blood alone act as a major risk factor for CVDs. Remedial lifestyle changes can help lower risk. Alterations in meal patterns is outlined as first line treatment to lower risk before pharmacological cure with decreased intake of saturated and trans fats. Further, plant sterols are a significant component of low fat diet that help lower LDL-C. Clinical trials show that consuming 2 g plant sterols reduce LDL-C by 10%. Plant sterols are compounds present in plant cell wall and are structurally similar to cholesterol with a difference in either a methyl or ethyl group. It competes with cholesterol for micelles thus reduce cholesterol absorption. Soy is one of the best plant based foods that serve as good option for people with hypercholesterolemia since it combines heart health benefits from both soy protein and plant sterols. (Weidner et ol., 2008)

 

Composition and benefits of Soy

 

According to a popular belief, animal protein is considered complete while plant protein incomplete. However, soy is a plant-based food that can be used as a substitute of animal protein. There is little saturated fat and no cholesterol in soy. 8 % of soy oil is linolenic acid. This suggests soy may be helpful in reducing the risk of heart diseases and has cholesterol lowering effect. According to Dr Brown and Goldstein, cholesterol level in blood should be between 100 and 150 mg. For this diet should be rich in fibre and antioxidants and low in fats.

 

A wealth of new research has revealed that soy not only have unequalled nutritional profile but also have anti-cancer effects. It has family of six compounds that provide soy anti cancer properties and includes:

 

  • Protease inhibitors- block genes that promote cancer

 

  • Phytates- act as antioxidants

 

  • Phytosterols- protect against carcinogenic bile acid

 

  • Saponins- anti-mutation, antioxidant

 

  • Phenolic compound- protect DNA

 

  • Isoflavones- block Estrogenic lowering the risk of breast cancer and also reduce risk of hormone dependent cancer such as prostate cancer

 

Soy has a compound Genistein (isoflavone) which has anti-cancer effects, suppress oncogenes, revert cancer cells to normal cells and also act as an antioxidant, thus is cardio protective and help maintain cholesterol levels between the normal range.

 

LDL-C is released by the liver and deposited in body cells including the cells of artery walls and increase the cholesterol levels. HDL-C on the other hand takes cholesterol back to the liver. Soy reduces total cholesterol and LDL-C and increase HDL-C. This suggests soy and/or soy products are effective in lowering TC and reduce risk of heart and other diseases. (The Defence Boasters- Flavonoids and Isoflavones)

 

Objectives

 

The aim of this review is to analyse the effectiveness of soy in reducing the risk of hyperlipidaemia. Other goals included;

  • evaluating the effectiveness of soy and/or soy products in preventing and treating heart diseases
  • measuring the quantity of soy to be consumed per day or per week

 

  • by what percentage cholesterol levels are reduced by consuming soy?

 

Review of literature

 

Cholesterol lowering effect of a soy drink enriched with plant sterols in a French population with moderate hypercholesterolemia

 

Soy based foods are used as an alternative of dairy products through out the world. A study on 50 subjects of french population was conducted to investigate the cholesterol lowering effect of a soy drink enriched with plant sterols in moderate hypercholesterolemia subjects. The subjects were given 200 mL of soy dink either enriched with or without plant sterols for 8 weeks and their lipid profiles checked at 0 day, 4 weeks and 8 weeks. The subjects were asked to maintain their diet and physical activity. The lipid profile showed reduction in LDL- C by 0.29 mol/l, TC by 0.26 mol/l and HDL-C by 0.31 mol/l. Consuming soy drinks enriched with plant sterols significantly reduce cholesterol levels and is convenient aid in managing mild to moderate hypercholesterolemia. (Weidner et ol., 2008)

 

Effects of soybean D-LeciVita product on serum lipids and fatty acid composition in type 2 diabetic patients with hyperlipidemia

 

The purpose of this study was to evaluate if dietary supplement of soybean D-LeciVita product, rich in polyunsaturated phospholipids (with 12% lecithin, 35% soy protein) affects serum lipids and serum and erythrocyte phospholipid fatty acid composition in type 2 diabetic patients. Forty-seven patients (men and post-menopausal women) with isolated hypertriglyceridemia (IHTG) and combined hyperlipidemia (CHL), aged 43–70 years, were given 15 g of D-LeciVita powder as a water suspension in a single evening dose during the follow-up period of 12 weeks. Patients kept their diabetic diet relatively constant. Results show a decrease in total serum cholesterol and triglycerides which indicates that soybean D-LeciVita product (combination of soy protein and lecithin) has both lipid and phospholipid fatty acid lowering effect in type 2 diabetic patients with hyperlipidemia.. (Medic et ol., 2005)

 

Dietary soy-derived isoflavone phytoestrogens: Could they have a role in coronary heart disease prevention?

 

Soy protein-containing foods are a rich source of isoflavone phytoestrogens, such as genistein and daidzein. There is great interest in these substances, as lower rates of chronic diseases, including coronary heart disease, have been associated with high dietary intake of soy-

 

containing foods. Soy phytoestrogens bind weakly to estrogen receptors, and some bind more strongly to estrogen receptor-β compared with estrogen receptor-α. A meta-analysis has indicated that isoflavone phytoestrogens lowered plasma cholesterol concentrations in subjects with initially elevated levels, but had little effect in subjects with normal cholesterol concentrations. These substances reportedly may also have beneficial effects on arterial endothelial function. (Tikkanen and Adlercreutz., 2000)

 

 

Health Effects of Soy Protein and Isoflavones in Humans

 

Epidemiological studies indicate that ingestion of soy reduces risk of many chronic diseases including cardiac failures. Soy protein is accepted as being cardio protective by the US FDA 1999. This idea is also supported by other states such as UK and Malaysia. Analysis done by American Heart Association since 1999 on isolated soy protein with isoflavone concluded that it lowers LDL cholesterol but has no effect on HDL, triglycerides and blood pressure. Processing methods and origin of soy beans determines the amount and intact ness of bioactive components. Different studies have also shown safety concerns such as on thyroid and reproductive health as well as on certain cancer types. However the data is insufficient to draw a conclusion.( Xiao CW, 2008)

 

Soy Food Consumption Is Associated with Lower Risk of Coronary Heart Disease in Chinese Women

 

Consuming soy reduces risk factors for heart diseases. However, data confirming this is limited. A study was conducted on 64:915 Chinese women aged 40 to 70 years between 1997 to 2000 with no disease such as diabetes, cancer or coronary heart disease. Dietary intake was assed via an in person interview. Food frequency questionnaire was conducted. The results of the study showed an inverse relationship between consuming soy product and incidence of heart diseases. (Ziang X., 2003)

 

Nutritional and Health Benefits of Soy Proteins†

 

Soy is used as a replacer of animal products. Although it has many positive health outcomes, it is low in the amino acids such as methionine, lysine. Infant formulas are thus fortified with these amino acids. Intake of uncooked soybeans act as inhibitors of digestive enzymes leading to poor digestion. Cooking soybean properly or eliminating these inhibitors by processing is significant. Despite proper heat treatment, some inhibitors still remains. These inhibitors are of enzymes such as chymotrypsin and trypsin. Other adverse effect include allergic reaction to soy protein. On the other hand, soy improves bone, oral and renal health. It is cardio protective, anti cancer, anti inflammatory. Soy is also effective in weight loss. (Friedman and L.Brandom., 2001)

 

Risks and Benefits of Soy Phytoestrogens in Cardiovascular Diseases, Cancer, Climacteric Symptoms and Osteoporosis

Phytoestrogens, lignin, isoflavones, coumestans are some compounds that are geometrically homogenous to Estrogen thus can attach to their receptors and lowers the risk of hormone dependent cancers such as breast and prostate cancer. These compounds are present in plant based foods such as fruits, nuts, grains. Isoflavones are also suspected to lower cholesterol levels. Isoflavones are beneficial in preventing and/or treating manifestations after menopause and also osteoporosis. These phytochemicals in soy and soy products is also assumed to cause chromosomal changes and mutations that promote thee activity of cancer promoting agents. However, data supporting these views is limited. (Cesare, 2012)

 

Equol status and blood lipid profile in hyperlipidemia after consumption of diets containing soy foods

 

Data proving the cholesterol lowering property of soy is insufficient. A study was done on Eighty-five hypercholesterolemic men and postmenopausal women (42 men, 43 women) to confirm soys effect on cholesterol. It was assumed that LDL-C was reduced in people who could convert isoflavone daidzein to equol. But the results of the study showed that bad cholesterol was reduced in both equol producers and non producers. Producers of equol had an additional benefit of maintaining higher levels of good cholesterol HDL. (MW Wong et ol., 2012)

 

Effects of Two- Month Consumption of 30 g a Day of Soy Protein Isolate or Skimmed Curd Protein on Blood Lipid Concentration in Russian Adults with Hyperlipidemia

 

According to American Heart Association, tharapeutic effect of soy is possible if its dose is 30 grams per day. This conclusion was drawn on the base of a study for short duration (4-6 weeks). Thus another study was done to confirm the results. The study was done on 30 Russian hyperlipidemic patients where motality rates due to cardiac conditions is high. These patients were either given soy protein isolate, (SPI) or skimmed curd protein (SMP) or Russian style cookies. This trial was of 5 months due to which only 28 subjects could complete the trial. Lipid profile were done before and after the trial to draw a conclusion. Exercise levels of the subjects were also considered. It was deduced by the study results that consuming 30 g/day soy was efficient in decreasing cholesterol levels. (A. Borodin et ol., 2012)

 

Conclusion

 

Soy can be used in place of animal proteins. It is beneficial in lowering risk for heart diseases and can be used as part of treatment plan for cardiovascular diseases. Consuming 200 ml soy drink lowers total cholesterol by 0.26 ml/l. 30 g/day of soy is needed to produce a tharapeutic effect. It decreases total and LDL-C but raises HDL-C thus lowers the major risk factor for CVDs, hyperlipidemia. Soy is anti -cancer, anti-inflammatory and antioxidant. It improves not only heart health but bone, oral, eye, skin health as well and is beneficial for diabetics. However, allergic response can occur against soy and it can also change chromosomes. Raw soy beans can act as inhibitors for digestive enzymes impairing digestion.

References

 

  • DeNysschen, C.A., Burton, H.W., Horvath, P.J. et al. Resistance training with soy vs whey protein supplements in hyperlipidemic males. J Int Soc Sports Nutr 6, 8 (2009). https://doi.org/10.1186/1550-2783-6-8

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