Duckweed – another nutrition fad?

One of our Nationals recently ran an article claiming  adding duckweed to your diet can result in 20% more weight loss.

But is there more to it? Is the research reliable?

To summarise; A group of “mildy obese, 50(ish) year-old, sedentary individuals” took part in a study where a group of researchers control every single thing they ate and made them exercise for 18 months

They also put you into 1 of 2 groups;

  • Regular food, but calorie controlled.
  • Super healthy food, calorie controlled

And when I say calorie-controlled, I mean a serious drop in calories compared to what they were used to. Down to 1,800 for the men and less for the women.

Guess what? All these people lost weight!

That is great news, but what about the Duckweed?


The duckweed intervention was as follows:

10 participants were given a duckweed shake for dinner for two weeks. The other 10 were given a yoghurt drink with the same carbs, protein and calories as the duckweed shake.

According to the article in The Times, the participants that had duckweed felt a bit fuller and lost more weight, 20% more in fact.

But that’s not actually what happened.

The participants were all part of the bigger, longer (18 month) study looking at the power of the Green Mediterranean Diet. Which I think we can all guess- is pretty good for you. They were comparing it to a not-so-virtuous diet with the same number of calories in it. The Mediterranean Diet group lost 20% more weight.

The Duckweed researchers borrowed 20 of these guys for two weeks and did the yoghurt vs duckweed comparison. And concluded: “Duckweed elicited a lower postprandial glucose peak compared with yogurt”.  Which simply means that blood sugar levels after eating duckweed were better than after eating yoghurt.

What the journalist has done has taken the results of the large Mediterranean diet study, and confuse those results with the two-week duckweed study. Oops! #awkward

I read the study again and again looking for the other experimental group, the ones that ate what they wanted, drank beer and wine had two Deliveroos a week and didn’t exercise but took duckweed powder and lost a load of weight…

But I couldn’t find it.


So, what have we learned today?

  • We’ve learned that a reduction in calories and an increase in exercise leads to weight loss and improved health markers.
  • We learned that green smoothies are better for you than yoghurt shakes.
  • We learned that journalists love a sensational superfood fad, and aren’t very good at understanding research
  • And of course, we learned that if something sounds too good to be true, it probably is.

BUT…. my morning researching duckweed wasn’t a complete waste of time. I can now tell you the following awesome facts about it:

For a plant it does have high levels of bioavailable amino acids and iron, which is great news for vegetarians whose diet may be lacking in these micronutrients.

It also contains bioavailable B12, an essential nutrient lacking in most vegetarian diets, and usually only found in animal products.

Duckweed is also excellent for phyto-remediation. This refers to the removal of contaminants from polluted groundwater.

At the moment, we’re not even sure what form Duckweed is set to hit our health food shop shelves in. Apparently, it’s available in powder form and frozen cubes. If you’re on a strict plant based diet and are looking for a way to get the nutrients more available in animal products and supplements, then Duckweed may be an option.

But as far as any misguided claims about miracle fat loss go, be very wary.

Alex Backhouse MSc

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