Emulsifiers and Heart Health

As we saw in last week’s newsletter, the media loves to scare us with sensational headlines. The latest one “This everyday ingredient is raising your risk of heart disease and stroke”, alarmed one of our most avid readers — Rachel’s mother — who asked us to comment on this article in our newsletter.

Well, mum, we’re happy to oblige. Let’s take a closer look at the evidence behind this headline.

The article claims that there is an everyday ingredient that is raising our risk of heart disease and stroke. What is it? Emulsifiers. These are substances that help mix things that normally don’t mix, like water and oil. They’re useful for keeping mixtures from separating over time. In simple terms, emulsifiers have a hydrophilic (water-loving) end and a hydrophobic (water-repelling) end. They bridge the gap between oil and water molecules, making them more stable and uniform.

Emulsifiers are used in many foods to make them look and feel better. For example, they are used in mayonnaise to keep the oil and vinegar from splitting, in salad dressings to keep them smooth and thick, and in ice cream to make it creamy and soft.

While the headline sounds alarming, there are plenty of reasons why we shouldn’t press the panic button just yet.

The source of this headline stems from a study published in BMJ, which drew upon data from the NutriNet-Santé cohort. This French cohort study was initiated in 2009 with the primary goal of exploring the links between nutrition and overall health. Recruitment began back in 2009 and is ongoing. This particular analysis included 95,442 adults.

This study is different from most other cohort studies in how it measures what people eat. While most cohort studies rely on food frequency questionnaires, this particular investigation opted for a different route — the use of multiple 24-hour dietary records. The objective was for participants to complete three 24-hour records initially and then follow up with these every six months. Notably, these records were web-based and self-administered. This methodology, like any other, comes with its share of advantages and disadvantages.

On the positive side, this approach allowed the researchers to collect detailed information regarding commercial brands and industrial products to figure out how much additives people consume. They used three different databases to identify which foods had additives. And for amounts, they relied on various sources, including data from lab tests, or information from the European Food Safety Authority and the Codex General Standard for Food Additives.

On the downside, over 20,000 participants were ditched from the analysis due to under-reporting, and an additional 9,000 were removed because they completed fewer than three 24-hour dietary records. This means one-quarter of participants were excluded from the final analysis. Errors also creep in when individuals record their own dietary information. When employing these web-based approaches like these, generic recipes are frequently used, leading to the loss of certain subtleties.

Furthermore, it's worth noting that while the dietary records underwent validation against energy and essential nutrients, there wasn't a specific validation process for assessing emulsifier intake.

Let’s see how this study made the headlines.

When we look at all emulsifiers (you'll need to venture into the not-so-easy to find 'supplementary' material), there is no link between eating more of them and the risk of total cardiovascular disease, coronary heart disease, or stroke. So, nothing to worry about here.

Interestingly, most of the emulsifiers people ate were sodium bicarbonate and modified starches. These made up 60% of the total. Then came pectins (6.4%) and diphosphates (5.1%). These also had no link with heart disease. Again, nothing that would make a good story.

So where did the scary headline come from? In their analysis, the authors assessed the relationship between heart disease and 19 categories of emulsifiers, some further broken down into sub-categories. In total, there were 38 emulsifier categories or sub-types evaluated for the three primary outcomes, adding up to a staggering 114 emulsifiers in total.

We know that when we do so many tests, some will look statistically significant by chance.

The emulsifiers that seemed to matter for heart disease were from the cellulose and mono- and diglyceride groups. The risk went up by 3% to 8% for each standard deviation increase in intake. A similar pattern was seen for CHD, where trisodium phosphate was also significant. For strokes, only one of the mono- and diglyceride emulsifiers was significant.

These were the associations that triggered the sensational headlines.

Now, let's consider where you might encounter these particular emulsifiers in your diet. For celluloses, they were most prevalent in cakes and biscuits (43.4%), processed potatoes and tubers (20.1%), processed fruits and vegetables (11.4%), and fats and sauces (11%). As for mono- and diglycerides, fats and sauces (22.5%) and cakes and biscuits (22%) topped the list, followed by pastries (14.4%) and confectionery (10.6%). When it comes to phosphates, cakes and biscuits contributed more than half of the intake (56.9%).

One could argue that these emulsifiers serve as markers for highly processed foods. Within these products, numerous other ingredients could potentially contribute to the observed associations with heart disease.

This suggests that the problem might not lie with the emulsifiers themselves, but rather the other things present in the foods containing them. People who ate more emulsifiers also ate more saturated fat, sodium, sugar, red and processed meats, and ultra-processed foods, and less fruits and vegetables and wholegrain foods. Even though the authors took steps to adjust for these other dietary factors, it's important to acknowledge that achieving perfect adjustment is a challenge.

Another concern on our radar is what we call residual confounding. This essentially means that there could be other distinctions between individuals who are high consumers and those who are low consumers that we might not have identified, and thus, we can't account for in our analysis.

These issues are common in cohort studies, which is why some people prefer intervention studies. The authors mention one RCT that found that eating a food additive called carboxymethylcellulose for 11 days changed the gut bacteria, caused stomach pain, and increased some chemicals that are linked to heart disease. However, it's crucial to note that the dose used in this trial was high at 15 g/day. This supraphysiological dose far exceeds the mean dose observed in this cohort study, which was 4.3 g/day. Even among the highest consumers, the mean intake was only 8.4 g/day.

So, what can we take away from this? There's no need to sound the alarm bells regarding emulsifiers at this point. But we may want to watch how much processed food we eat. These foods not only have additives, but can also be high in saturated fat, sugar, and salt.

And if you want to eat less emulsifiers, opting for whole foods over highly processed ones could be a prudent choice.