Is plant protein linked to healthier ageing in women?

A recent study argued this is the case, at least in women under 60, and it got international coverage. But here’s why we can’t take what the media tells us at face value.

This research came out of Harvard. It used information on almost 49,000 women, from one of the biggest and longest running (since 1976) data banks on women’s health in US history.

Credible, you’d think: Harvard, big numbers, well-established. So what’s the problem? There were many, but here’s a handful.

First, and I know I’ve said this lots of times before, nutrition research is hard to do well. That’s because it’s almost impossible to separate what we eat from all the other things we do.

It’s also hard to know what people really eat. If you ask them, you’ll get whatever they tell you, which might or might not be accurate. We humans are forgetful and like to think we eat better than we do.

In a typical nutrition study, we give people a list of foods and ask them to tell us how often they eat them. We also ask what’s happening with their health. Then we give those data to the computer and ask it to show us the connections.

At best it can show us a link, one that needs more investigation before we can make too many claims. Because a link is just that; it’s not proof that whatever people have eaten has caused their good or bad health.

What was interesting— and odd — about the Harvard study was that they collected their dietary data in 1984 and 1986, when the women must have been in their 20s, then assessed them for healthy ageing (by asking them what physical and mental issues they had) in 2014 and 2016. Thirty years later. As though what we eat in our 20s remains unchanged through to our 50s.

On top of that, their results, as we’d say in this country, don’t pass the pub test.

These days we might think of plant protein as, say, nuts and seeds, legumes, or tofu. But in the mid-80s the researchers decided it meant foods such as bread, fries, pizza, pasta, cereal, mashed potato, and baked goods (i.e. cakes, biscuits, pastries).

Somehow, they concluded that eating animal protein (beef, chicken, seafood, milk and cheese) which we know is rich in nutrients and beneficial for muscle and bone, made no difference to healthy ageing.

But eating so-called plant protein (bread, fries, pizza and so on) did. Hmmm, doubtful.

Healthy ageing was defined as being free from chronic disease, having good mental health, and having no issues with memory or physical function.

Trouble is, unless someone takes the time to read beyond the headlines, this gets trotted out as plant protein is better for healthy ageing.

An online women’s health site ran an article about it with this heading: Plant proteins are key to healthy ageing among women: here’s why.

The study was described as groundbreaking, and readers were told it showed that “plant proteins hold much higher value than animal proteins when it comes to women’s health and healthy ageing”.

An Indian newspaper got a local academic to comment. He said it was proof of the benefits of dal and rice. All those micronutrients and polyphenols. Never mind that white American women in the 1980s were unlikely to be eating a diet of dal and rice.

Nonetheless he concluded that “a balanced diet should be plant-based with animal proteins as an optional component”.

All media outlets need content, it’s not hard to find someone with a barrow to push, and people often don’t have the time or interest in making sure that what they’re saying is true. Most will just rely on the blurb from the Harvard marketing department because… Harvard.

Sadly, that brand doesn’t mean what it used to, at least where nutrition research is concerned.

All of which is tricky for us when we’re skimming through a newspaper or scrolling through our social media feed. We’re short of time too but trying to stay on top of things. And we want to believe what comes from a trusted name.

The bottom line is that while plant proteins deserve a place in our diets because they provide nutrients, fibre, and variety, animal proteins are vital for healthy ageing too. Especially after age 60.

Just skip the Harvard mid-80s version of plant protein.

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