Heart Health

Soy may favorably affect risk factors for CHD, the leading cause of death in America

By November 3, 2021 No Comments
Soy may favorably affect risk factors for CHD, the leading cause of death in America

The cholesterol-lowering effect of soy protein is well established,1-8 but there is also intriguing evidence that independent of cholesterol, soy favorably affects coronary heart disease (CHD) risk factors.

CHD is the leading cause of mortality among Americans according to newly published data by He et al.9 It accounts for about one out of every five deaths. CHD remains the number one killer even though blood cholesterol levels have come down dramatically over the past 20 years. Over this period, mean serum total cholesterol levels decreased from 203.3 mg/dL to 188.5 mg/dL.10 Does this mean elevated cholesterol isn’t a major CHD risk factor? Of course not, but it does mean that it is only one among many such factors.

In 2020, projections are that of the 3.3 million deaths in the U.S., 690,882 were due to CHD (20.6%). Followed closely by cancer, which is thought to be responsible for 598,932 deaths (17.8%).  For year 2020, it is worth mentioning that 345,323 Americans died of COVID-19, so there is a large jump in total deaths compared to recent years.

The good news is that cholesterol levels have come down, as has the prevalence of smoking, although 18.1% of Americans still smoke.10 Depending on age and gender, people who smoke are anywhere from two to four times more likely to die from CHD.11 In contrast to smoking and cholesterol, where improvements were noted, from 1999-2000 to 2017-2018, age- and sex-adjusted mean body mass index increased from 28.0 to 29.8. There are several dietary hypotheses about the increasing prevalence of overweight and obesity,12 but it isn’t clear that any particular dietary approach aids in weight loss more than another.13 However, if higher protein diets aid in weight loss, as some but not all evidence indicates,14 then the higher protein content of soybeans compared to other legumes is notable.15

Another risk factor examined by He et al. is blood pressure.10 Mean systolic blood pressure decreased from 123.5mmHg in 1999-2000 to 120.5mmHg in 2009-2010, then increased to 122.8mmHg in 2017-2018.10  So, what is known about the effect of soy on blood pressure?

Several meta-analyses of clinical studies have examined the effects of soy on this outcome. For example, in 2011, Dong et al.16 found that soy protein lowered both systolic blood pressure (SBP) and diastolic blood pressure (DBP) in both normotensive and hypertensive individuals, although the effect was greater in the latter. One year later, Liu et al.17 found that soy isoflavones lowered blood pressure in hypertensive subjects, but not in normotensive subjects. In 2017, Kou et al.18 found that both soy protein and isoflavones lowered blood pressure in postmenopausal women, but only in response to an intake of at least 25g/d soy protein or at least 100mg/d isoflavones. Also, Mosallanezhad et al.19 found that soy significantly lowered SBP and DBP; however, subgroup analysis showed a reduction in both SBP and DBP only in younger participants with lower baseline DBP and intervention durations of <16 weeks. Overall, there is suggestive evidence that one or more components of soy lowers blood pressure, but it would be premature to definitively conclude this is the case.

Finally, mean hemoglobin A1c increased from 5.4% to 5.7% between 1999-2000 and 2017-2018. 10  In 2021, Mohammadifard et al.20 found that in patients with the metabolic syndrome soy products lowered fasting blood sugar and insulin levels and decreased insulin resistance. Also, in 2021, Asbaghi et al.21 found in patients with diabetes, there was a reduction in fasting blood glucose levels but only in individuals with elevated fasting blood glucose levels at baseline and who consumed more than 30g/d soy protein. These two analyses suggest that soy might help control A1c levels.

In conclusion, there is intriguing evidence that soy consumption favorably affects multiple risk factors for CHD, the leading cause of death among Americans.


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This blog sponsored by SNI Global and the United Soybean Board.

Dr. Mark Messina

Author Dr. Mark Messina

PhD in Nutrition, Executive Director, Soy Nutrition Institute. Expert in soyfoods and isoflavones.

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