Can you survive purely on a diet of avocados?

We put Tracey's question to nutrition expert Toni Steer...

Toni - That's an interesting one. Avocados have got things going for them so, for example, they are quite high in what we call a healthier fat, which is the monounsaturates, and the monounsaturated fats have been shown to modify your blood fat levels more favourably than things like saturated fat.

Chris - So when we have them, although you're getting a lot of 'fat' calories coming in, it's 'good for you fat' in the same way that olive oil is said to be 'good for you fat', this monounsaturated fat?

Toni - Yes. So overall you want to aim to reduce the amount of fat in your diet but, the fat that you do include, you want to modify; and avocados have got that kind of monounsaturated fat that is more desirable. One of the other things that avocados have got is that they've got some reasonable amounts of fibre, so around 3.5 grams of fibre per 100 grams, so that would an average avocado. They also contain potassium, like many fruits and vegetables.

Chris - So making them mildly radioactive?

Toni - Yes..

Chris - Aren't they Dave. Aren't bananas a little bit radioactive because they've got lots of potassium in them?

Dave - Yes it's the same isotopic form of potassium that they use in our hospitals and it's just floating around...

Chris - Potassium-40?

Toni - If you eat potassium then you're going to get irradiated slightly!

Chris - Because also Brazil nuts are radioactive, because of the soil they grow on and someone did tell me that you can equate a chest X-ray to the equivalent of a bag of brazil nuts. You get about the same dose of radiation equivalent to doing the two things. Anyway, I didn't mean to hijack your answer Toni, so do carry on and tell us about avocados. Is Tracey going to be okay?

Toni - The other thing that's quite interesting with them is there's some suggestion that adding avocados to other meals can enhance your carotenoid or vitamin A absorption. The evidence is kind of a little bit weak in that area. I think it's still really to be confirmed.

Chris - Is the rationale just because there's just loads of fat in the avocado?

Toni - Yes, so fat soluble...

Chris - And vitamin A's a fat soluble vitamin, so it helps?

Toni - Absolutely. What I would say though is on the downside, avocados are not really a great source of things like vitamin C, they're quite low in calcium, for example, not much iron so, actually, would you really want to survive just on a diet of avocados and, actually, you are going to be lacking.