WKD YOGA

Protein - are we eating enough? (inspired by some 'Zoe' podcasts)

We are trying to get to grips with this much debated subject, after lots of listening and reading, we've tried to highlight some of the key issues. We need protein as part of a balanced diet to help maintain / build muscle and other structures in the body. There seems to be a big surge in the popularity of protein, with bars and shakes just the start. General guidance has been that we should consume 0.83g per kg of body weight. So for example, if you weigh 70kg, that's 58 grams of protein per day. Though, as we are all unique, we need different amounts, and that might be too much for some. Most people manage the 0.8g without additional bars and shakes etc. as it's not common for people to be protein deficient. The problem with eating the extras is that they are usually highly processed with lots of additives, just take a look at the ingredients. The 'over consumption' or prioritising of protein might lead to under consumption of other important food groups eg. fibre, which is generally under consumed. And the body can't store protein, any excess will get converted to carbs and fat!

The other factor to consider, and often a big point of contention is the source of our protein. There is the environmental impact, beef from cows (from beef herd, as opposed to dairy herd), at about 50kg of 'greenhouse gas emissions' per 100g, has the biggest negative impact on the environment, whilst pulses and peas are less than 1kg per 100g, see graph. This doesn't take into consideration other environmental impacts such as use of water or land etc. beef scores the worse on water per kilo, especially if it is fed on 'feed' rather than naturally on grass. Some nuts are quite high in water usage. 

The next point, that invariably comes up in these discussions is the 'quality' of protein and our ability to absorb the protein (bioavailability). It is often said that you can't get all you need from plants, the protein is not the same, it is 'incomplete'. And that plant protein is less bioavailable. The body absorbs individual amino acids, which then get put back together. It doesn't differnetiate between amino acid 'a' from a piece of broccoli or from a piece of fish. Plant protein contains the 20 amino acids including the 9 essential ones (that we need to get from our diet), but the ratios of the amnio acids varies from one source to another, so a variety of plant sources is encouraged. If you ate all your calories from one source eg. rice, you would fall short of the recommended daily intake in some of the amino acids. This is the same for example if you compare an egg to a piece of fish etc. If you eat another mammal, it's more similar to eating yourself, so you get all the amino acids in the same ratio that we need (and they are slightly more bioavailable), but you also get other unwanted stuff, and also miss out on fibre and the many other beneficial attributes of plants. The table below shows a bit more detail on ratios in different food groups.

As vegetables are typically lower in protein per 100g than meat, you need to eat more veg than meat to get the same amount of protein. So, maybe if you are fully 'plant based' you might need to be a little more 'protein aware' or just make sure you eat a decent variety. The levels of bioavailability also vary, so if a product contains 'x' grams of protein, you might not be able to absorb 100% of it. That can change or be influenced by cooking / preparation, or what combinations of foods you are having, there is not enough data on this yet. 

It might be interesting to see what you might consume on a particular day, there's probably an app to help calculate it, if you find it a bit tricky. If the product doesn't have a nutritional label, the internet can help, but also be a bit random. We've seen a wide range of estimates for g/100g for lots of food stuffs. A jar of 100% peanut butter in our cupboard is coming in at 28.5g/100g of protein. Setian (made from gluten /wheat protein is the highest we found at 75g/100g. Beef ranges from 21-32g/100g. It is now fairly widely accepted that there are lots of long term health benefits of plant protein, whereas there are long term risks to over consumption of red meat. 

If you want to listen to a longer discussion, here's a link to an apple podcast by the 'Zoe' Science and Nutrition team. There's another (more fun) Zoe podcast on protein with Professor Christopher Gardener on youtube here who concludes - stop obsessing about protein, just eat food and lots of beans!