Can eating Tofu prevent heart disease?

Heart disease (Cardiovascular Diseases) have been the main reason of death over the past six decades. While in 1961 more than 50% of deaths in the UK were due to heart disease, this rate fell to 32% in 2009. However, heart disease is still the number one cause of death in the UK and globally (17.6 million deaths globally attributed to heart disease in 2016). This number is expected to grow to 23.6 million in 2030 (WHO, 2010) which means that although a lot of research has been done in this area, heart disease is still beyond our full understanding and a lot of research needs to be done in this area.

Although we don’t know the full detailed picture about the mechanism that leads to heart disease, we believe that many risk factors play a critical role in the development process. These factors include smoking, poor diet, physical activity, alcohol and obesity. In addition, it is critical to treat other diseases that may lead to heart disease such as diabetes, hypertension and high blood lipids. Although the coronavirus pandemic has been widely covered by the media since the beginning of this year, some reports covered recent research findings highlighting the possibility of reducing the heart disease death rates by eating tofu. “Eating tofu more than once a week slashes the risk of heart disease by nearly a fifth, research finds” The Sun. This article mentions the positive results that a newly published study has shown which I will now discuss in more detail.

What did the study do?

The study was carried out in the US and enrolled 238,371 female nurses (25-55 years) and 51,529 male health professionals (40-70 years). Participants were asked to complete a questionnaire related to their food intake every 4 years to measure their tofu consumption along with other 130 food items. Participants also filled another follow-up questionnaire every 2 years to assess the effects of other factors that may contribute to the disease development such as body weight, smoking and physical activity.

The study was initiated in 1976 and ended in 2013 covering a long period follow-up. The incidence of coronary heart disease (defined as nonfatal myocardial infraction and fatal coronary heart disease) was then recorded. While 210,700 participants completed the study, only 8,258 consumed tofu for more than once a week.

The study showed that higher isoflavones (compounds that are found in very high levels in soy) intake is associated with moderately lower risk of coronary heart disease. It’s worth mentioning that tofu contributed to only about 35% of the total isoflavone intake. Soymilk, for example, contributed to 23% of total isoflavone intake.

This conclusion was driven from 8,359 participants who died due to heart disease. However, 2,733 participants had no medical records indicating the death was due to heart disease although their death certificates showed so. It would be interesting to re-analyse the data including only medically confirmed deaths due to this.

About the article

The article headline was phrased as “Eating tofu more than once a week slashes the risk of heart disease by nearly a fifth, research finds”. However, this is not very accurate as we don’t know whether tofu was the only factor which led to these results. The article also mentioned that data was generated from 200,000 people. Although this is quite a large number of participants, it was important to point out that participants were only US nurses and health professionals. Research with a more diverse population is needed to indicate that tofu is going to help everyone.

As we have seen with many articles, the writer used a catchy title with polished summary at the beginning which is the only part of the article many people will have read. However, it was good that the writer quoted the researcher’s point that tofu is not a magic bullet and more data is needed to better interpret these findings. This shows the importance of reading articles in full as we can sometimes see more balanced and scientific discussions towards the end.

Other things to keep in mind

• The study was only carried out in the US and we don’t know whether these findings apply to all men and women in other countries such as the UK.
• Only nurses and health professional where enrolled and we don’t know how that applies to other population backgrounds.
• The data collected depended on self-reports which could sometimes lack accuracy. A better scientific conclusion could be driven by using biomarkers that trace the metabolism and intake of isoflavones but tracing this is going to be quite expensive.
• Finally, it is important to point that food processing may lead to the loss of isoflavones and there is a lack of information about the nature and quality of isoflavones consumed.