Will that high protein diet kill you?

After last Tuesday’s television show ‘how not to get cancer’ I got a number of concerned emails and Facebook messages from people questioning their protein intake. Specifically,  information that a high protein diet increases health risk and mortality. As a nutritionist who advocates a higher protein load, here’s what I’ve read about the role of protein and disease, as written by people much smarter than I am:

Information regarding health risks associated with a high protein intake has been critically reviewed by experts in the field, specifically the way the population dietary data from the National Health and Nutrition Examination Studies (NHANES) was analysed to determine that higher levels of protein increase overall health risk. The major criticisms were:

  • They eliminated half of the data points with no explanation;
  • Their definition of low protein (below 10%) should in fact be labelled as ‘inadequate protein’ as defined by the Institute of Medicine (IOM) protein ranges (10-35% of dietary energy), and in New Zealand adequate protein is 15-25% of energy in diet. The arbitrary cut-off used by the authors meant less than 450 people fell into the ‘low protein’ group;
  • The population data gathered dietary information via a single 24-hour diet recall once in an 18-year period; and
  • Body weight or body mass index (BMI) was not reported – given the clear association between excess body fat and chronic disease such as cancer, cardiovascular disease etc, this was a massive oversight.

While the paper outlined in the review also looked at laboratory trials, these were based on rodent studies and not clinical trials in humans. Differences in metabolic rate, the way we utilise nutrients and digestive tracts (the rodents more able to handle fibrous foods than ours) means that, despite interesting findings, we cannot conflate the findings here to humans, as they are not directly transferable.

Other points to note regarding research suggesting that a lower protein diet is good for longevity:

  • Many of the studies are based on rodent studies (not humans) and, in addition to what I posted above, the type of protein studied is typically casein – a dairy protein that has more potential to be inflammatory and one rodents are not naturally adapted to consume;
  • High amounts of dairy protein have been found to increase insulin, triglycerides and result in excess body fat compared to other sources of protein provided to the rodents;
  • Much of the research also show that it could be an effect of a high methionine intake which – when not balanced with other amino acids such as gelatin) for some people, can build up the amount of homocysteine (another amino acid) that increases risk of cardiovascular disease;
  • As we age, we are at greater risk of sarcopenia, dyopenia and poor health due to falls if we don’t have a decent amount of muscle mass, which requires protein to help lay down this muscle;
  • The majority of studies point to a higher protein intake being protective for quality of life as we age, not detrimental; and
  • We become more anabolic resistant as we age, meaning we are unable to lay down muscle the way we are when we are younger to the same extent. This could be as a result of both inactivity and lower levels of oestrogen and testosterone, meaning the a higher protein intake is required (in addition to resistance training).

And here is what I know regarding a low protein diet in the real-world setting:

  1. People are hungry. Women, especially, struggle to eat an appropriate amount of food when they restrict protein. This restriction (intentional or otherwise) leads to poor blood sugar control, poor appetite control and mood problems (either low mood or increased anxiety).
  2. People can only restrict for so long until it backfires. A lower protein intake might be totally fine on a Monday, things are okay on a Tuesday, but by Wednesday people are climbing the walls looking for something to eat. Or, for some, this process happens across the course of a day. This means that despite having a decent amount of food at dinner, the undereating of protein across the day leaves you standing in the kitchen at 8pm looking for something to eat and wondering why you are not hungry, but just ‘not satisfied’.
  3. Practically speaking, when you restrict protein, what is there left to eat? Carbohydrate. We eat until our minimum requirement for protein is filled and, in the absence of quality protein sources we will overeat on calories (specifically carbohydrate calories) until this requirement is met. For many, this results in poor nutrient status, poor blood sugar control and excess body fat. It’s these three things which have consistently been found to result in increased risk of metabolic disease and cancer, not the protein load.
  4. People (generally speaking) fare best when we base their meals around protein and then toggle the fat and carbohydrate around that, based on their body composition and their activity levels. For many, this is more than a palm sized serve at each meal, and across the course of the day, for most people, this is at least 100g of protein from foods that are quality protein foods. In New Zealand, we get most of our protein (according to the most recent nutrition survey – which is 10 years old, actually) from bread. Bread! Wheat derived protein is one of the lower quality sources we can eat, with the amino acids not being as easy to digest and assimilate as those from animal-based sources.

So, clinically I am not at all concerned about advocating a moderate-high protein load for most people, and the television show last Tuesday did nothing to change my view on it. A longevity diet approach which is low in protein looks promising for a week a few times a year to confer benefits of fasting related to lifespan, but in terms of a day-to-day diet it will likely leave you frail, hungry and irritable. There is not enough human data to show that this approach will lead to a longer life, but I gotta say, it doesn’t sound like an enjoyable way to live beyond 100 years. Most evidence points to muscle mass being extremely important as we age to maintain quality of life and health span. This requires adequate protein and resistance training. In the words of Robb Wolf (as said on a recent podcast), we need to “eat and move in a way that lays down as much muscle as we can now, and then fight like the devil to keep it”.

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A good source of protein, and pretty delicious (PC: healthline.com)

What’s the best exercise for longevity?

Well, that’s a bit of a loaded question, really. As any is better than none, and there will be different points of views by different experts (of which I am not one of them). However, the older I get, the more I am interested in the effects of ageing on our overall health span. Ageing is unavoidable; it happens to the best of us. Listed below are some of the physiological and biological changes that can occur the older we become:

  1. Insulin resistance – this is in healthy weight older adults also, with research showingthere is more peripheral insulin resistance compared to a younger population (an inability to dispose of glucose into the tissue).
  2. Decreased availability of anabolic hormones, and increased frailty with lower levels of hormones
  3. Increased anabolic resistance, so not only is there a decrease in the hormones that signal tissue growth, the muscle tissue is less responsive to the stimulus of amino acids (protein) and exercise, and there is less muscle protein synthesis in comparison to breakdown.
  4. Greater protein requirementsfor the same relative gains in muscle, strength and function compared to a younger population
  5. Decreased motor neuron function, therefore less neural signalling to muscle tissues and reduced motor function.
  6. Increased intracellular oxidative stress, causing inflammation and reduced cell functioning
  7. Reduction in satellite (stem) cellsnumbers and regenerative capacity – these cells are essential for the maintenance and repair tissues in normal physiological processes or in response to muscle damage/trauma.
  8. Elevated myostatin signalling, a protein that blocks our ability to build muscle
  9. Increased chronic inflammation (also known as inflamm-aging)
  10. Changes in autophagy, where ageing reduces our ability to clear out damaged DNA
  11. Mitochondrial functioning abnormalities, where we can’t utilise energy metabolites as effectively to fuel mitochondria
  12. Reduced ability to be physically active (due to many of the reasons listed above)

This is a long, daunting and rather depressing list of what can occur as we age – and we are an ageing population. There is no doubt that if we don’t look after the body we have got, then we really are staring down the barrel of a loaded gun. The list above describes many of the mechanisms to explain the loss of muscle mass and function. It’s not about being ripped or having gainz, it’s about having proper functioning of the muscle so it can work effectively in our older years. This is what is shown to have the most positive impact on our cardiovascular, neurological and musculoskeletal systems.

Inactivity is the broader environmental issue that we need to address any (and all) of the physiological issues I have mentioned above. We need to be active – in everyday life, and with some structured activity too. Hanging out washing and housework isn’t going to cut it, I’m afraid. I see a lot of people who have this idea that you don’t need to exercise in order to lose weight, and you can do it solely on diet alone. This is true, of course, but when you embark on any weight loss plan that restricts calories (i.e. any weight loss plan that is out there), then you will lose both fat weight and muscle mass – lowering your overall metabolic rate along with it. This is one of the reasons why weight regain is so prevalent, however the powerful combination of diet plus exercise helps sustainable weight loss. As I alluded to above, exercise isn’t just moving around the house, doing chores – this should just be part of everyday living. Data looking at the effects of exercise show that resistance training confers benefits over and above what we would see if we were just doing 30 minutes exercise per day.

The right type and duration of exercise:

The challenge is to get people exercising. And this is especially so for those who read what I have said above, and think that – on top of 30 minutes of aerobic training they don’t have time to do, they then need to put some resistance (or weight) training in.

I’m not writing this to encourage you to find an additional 3 hours in your week, though.

In fact, a study that is yet to be published (I heard about it on STEM talk) suggests that just 72 minutes a week in total is enough to help many of the conditions associated with ageing and poor health that I’ve mentioned above. Egan and colleagues found a combination of both resistance and cardiovascular exercise in a circuit-type setting for adults over 65 years just three times a week for 24 minutes increased walking speed, leg strength and reduced trunk fat. These measures speak to better muscular function, obviously increased strength, and will help reduce metabolic health risk. The improvements were more potent in this combined group than either resistance training or aerobic training for the same duration.

So this was a very long preamble to the main message: if you are currently NOT exercising, then please start. While there are modalities that are better than others, seriously, anything will be better than nothing. The study I talked about is in older adults, you likely don’t need me to tell you that any age you start is obviously better than not starting at all. AND the earlier you start, the better the overall health outcomes.

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Seriously. Those pink dumbbells. Because obviously an older female couldn’t possibly lift anything heavier, right?! (PC:www.fabafterfifty.co.uk).