In this discussion we are going to look at the role protein plays in the body, whilst determining what optimal levels are for you and reviewing whether too much protein can be bad for you.
Protein when translated means of prime importance, so when thinking about supporting an individuals health I often look at their protein intake as priority. I often see signs and symptoms of protein insufficiency, especially symptoms relating to poor hair, skin and nail health. Whether this is directly due to the amount of protein consumed or related to improper digestion is a matter of investigation.
Other signs of protein insufficiency include, trouble building or sustaining muscle mass, slow recovery from exercise or injury, fatigue, mood and cognitive issues, trouble lowering body fat and regular colds and infections. As you can see the symptoms can be wide spread so let’s get started with understanding more about the important roles protein plays in our health before reviewing what might be the right level for you.
Why is protein important?
Protein is needed to produce things like enzymes, hormones, brain chemicals known as neurotransmitters like serotonin and dopamine which impact how we feel and function as well as immune molecules known as antibodies.
Protein is crucial in things like the regeneration/replacement of cells, something that can impact any area of health. As mentioned earlier, symptomatically some of the things you see initially with a protein insufficiency are poor skin, hair and/or nail quality.
In reality we need a level of protein that helps optimise our health and not just avoidance of deficiency. Adequate protein intake is well established in supporting metabolism, helping with your weight management goals, increasing satiety, energy production and performance as well as good immune function.
Unlike carbohydrates and fats, which we can store in the body more readily, with protein we have to regularly replenish it. Otherwise we run the risk of utilising our own protein stores – this might mean breaking down muscle tissue and even other proteins in the body such as proteins that make up the structure of our gut lining.
Have no fear though. Meeting your protein requirements is not overly challenging, even with vegetarians and vegans, meeting protein requirements to sustain life and preserve our own muscle tissue is actually quite easy. This becomes more challenging the more active you are, the higher the levels of stress you are exposed to and generally the more demands placed upon the body.
How much protein is right for you?
As mentioned previously everyone is a little different, it really depends on your activity levels, body composition such as height, weight, muscle mass etc and daily stress placed upon the body. So let’s look at some of the guidelines now.
For sedentary individuals without goals relating to reducing body fat or increasing lean mass the minimum requirement is said to be around 0.8g per kg of bodyweight per day. I’d probably suggest around 0.8-1.2g per kg of body weight per day being an acceptable goal for that group.
As we increase activity levels protein requirements also increase. Very active individuals, such as those training most days and performing strenuous activity may want to eat more like 1.5-2.2g per kg of body weight. Some extremely active individuals levels above this may even be required, however this is rare, typically only the case with extreme exercisers and should be done under the guidance of a qualified practitioner.
On the most part I have found the sweet spot for the majority people to be somewhere around 1.2-2.0g of protein per kg or bodyweight.
In some overweight/obese individuals this equation may have to be adjusted to their lean mass – something that can be quite easily predicted using simple body composition assessment scales in some high street health stores or simple bioimpedance bathroom scales can do the trick. They may not be completely accurate but they will provide a rough idea of lean mass. Another simple way of calculating is to use your goal body weight as the marker for these equations instead.
Total calories and other macronutrients matter
The levels of your other macronutrients also matter. If you are lowering your carbohydrate and/or fat intake and creating a calorie deficit to help lose weight then it is crucial to keep protein levels higher than the minimum amounts as this will help you preserve muscle mass and support your metabolism as you lose weight.
In 99.9% of cases, weight loss should not involve muscle mass loss. I have only had to consider muscle mass loss in specific circumstances with clients such as performing emaciation protocols for the cast on the movie ‘Unbroken’ and Chris Hemsworth for his role in the movie ‘In the Heart of the Sea’ and when preparing the stunt doubles of specific actors in similar roles. Never with any other clients have I seen the need to consider losing muscle mass as part of a weight loss protocol or any other protocol for that matter.
Carbohydrates and fats have the capability of being protein sparing, meaning when their levels are a little higher there is less demand on our protein intake and levels can drop without ill effect on our health or body composition. However if you are dropping calories significantly to help with weight loss one of the best things you can do is keep your protein intake high, probably closer to the 2g per kg of bodyweight per day mark.
Can eating too much protein be bad for you?
This is a very common question that I will be asked. The short answer is no, at least not for the general population. Below you will find discussion into specific health populations that may want to consider the negative impacts of high protein diets or diets that result in an imbalance of the proteins consumed potentially resulting in increase health risk.
Let’s start by looking at kidney function and protein intake. When it comes to kidneys, studies that have looked at ranges from 1.28-2.8g per kg of bodyweight, none have shown any significant changes in kidney function.
In clinic I have seen increases in urea levels in the blood above optimal ranges, however this is a natural byproduct of protein metabolism and expected when protein levels increase. To date I have never seen any other changes in blood measurements when we have increased protein intake. Having said that there is no point in eating an extremely high protein intake if your body just doesn’t need that amount of protein and in some cases excessive protein can be stored as fat as well.
I would suggest that increasing protein intake gradually may be worth doing as some research studies have noted changes in kidney function markers when significant jumps in protein intake occur. By significant jumps that would involve doubling your protein intake or going from a diet with 10-15% of the calorie intake from protein in the diet to 35-45% of the calories consumed from protein.
If you do have issues with your kidneys then a more restricted protein diet may well be required and any changes in protein intake should be very gradual and made under the supervision of a specialist who is keeping an eye on your specific kidney function markers.
A similar story is true with the liver. Consistent intake of higher levels of protein appears not to have any effects on the health of the liver, whereas significantly high protein re-feeding after a low protein intake does seem to have short-term effects on liver function.
Reducing exposure to aflatoxin, a toxic mold produced by certain foods when on a higher protein diet does seem to be warranted. High protein diets can activate the toxin in the liver more readily, making it more carcinogenic (cancer producing) and problematic. Sources of aflatoxin include corn, peanuts, milk, pistachios, Brazil nuts, walnuts, grains, soybeans, dried spices, cottonseed oil and figs. Let’s not freak out though, some of these foods are generally regarded as healthy and this may only be an issue in small populations that have issues with these types of toxins or as we have been mentioning here when protein levels are high.
Protein intake during pregnancy also seems to be somewhat of an issue. Higher protein and lower carb diets during pregnancy have been associated with a decrease in mass at birth and some studies have linked higher protein diets with elevated blood pressure and increases in the stress hormone cortisol in the offspring, nothing concrete in the research but interesting correlations nonetheless. During pregnancy there is often a need to ensure adequate carbohydrate intake to support proper fetal development and many experts suggest protein to be around 15% of total calories consumed, carbohydrates to be around 30-40% and the remainder from fats.
A lot of you may also have heard that high protein diets can increase your risk of cancer, you may have even read the headlines that diets high in meats, eggs and dairy could be as harmful to health as smoking, and whilst pro vegans will latch on to this and hardy meat eaters will rubbish these claims, is there an element of truth to it all?
The element of truth comes from one of the amino acids, methionine. Methionine restriction alone was shown to lower something called insulin like growth factor-1 (IGF1). That is interesting because IGF1 has been associated with encouraging the growth of cancer cells. Although methionine is found in all proteins in nature, it is particularly rich in muscle meats and eggs, although nuts appear to have the highest levels per gram of protein content, thus a higher concentration of methionine. Fruits and vegetables are lowest in methionine, thus a healthy vegan diet tends to be lower in methionine compared to meat eating counterparts.
Interestingly the goal may not be methionine restriction, but instead keeping the balance of methionine with another amino acid called glycine, something that is found in high sources in connective tissue and as a result a good food source is bone broth. Studies on methionine restriction when someone already has cancer are ongoing and may well be a consideration for that population, however the benefit of methionine restriction without the presence of cancer is still unknown and requires more research. All said and done we probably do eat excessive amounts of muscle meats these days and rarely do we consume the whole animal such as making use of the bones and other parts of the animal.
One of the most important considerations is the quality of the protein that is consumed. For example, if someone chooses to eat animal protein it should be noted that not all animal protein for food consumption is created equal and this is rarely distinguished in research looking at protein intake or meat eaters vs vegetarians/vegans. We should be considering what the animals are fed, their living conditions and what they are exposed to in terms of medications, and potentially certain hormones as this will of course impact the balance of nutrients in that food and our risk of exposure to antibiotic and hormone residues that may indeed impact our health over time.
- Protein intake is crucial to human health, supporting hormones, enzymes, immune health, body composition, energy production, cellular health thus about any function in the human body.
- Minimum levels are around 0.8g of protein per kg of bodyweight per day, but optimal levels should be higher for the majority of individuals.
- The more we exercise, the higher the levels of stress we have the higher the protein intake should be.
- Protein even at higher levels is generally regarded as safe unless you have underlying kidney issues or are pregnant.
- Try not to completely rely on muscle meats as your only source of protein.
- Increasing protein intake is a really important consideration when optimising body composition, particularly when lowering calories.
- If choosing to eat animal products, choose mindfully and be conscious of what that animal has been exposed to before you expose yourself to it.
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- Blumfield & Collins (2014) High-protein diets during pregnancy: healthful or harmful for offspring, American Journal of Clinical Nutrition, Oct Vol 4: pp993-995
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