How much protein should you consume? – A look at the risks of protein rich diets
There is a lot of hype these days for protein-rich diets. Everywhere you look now there seems to be an increasing amount of products that are labeled as being high in protein. Not simply on the back along with all the other macronutrients but branded right on the front in big bold letters.
It has long been known that protein is an essential nutrient and it’s relationship with building muscle in well known. Now there seems to be an increasing trend of companies and products trying to take advantage of this, marketing their products as high in protein but is a protein-rich diet healthy?
How much Protein?
The Institute of Medicine has set the dietary reference intake of protein as 10-35% of the total calories consumed per day. For reference, 1 gram of protein is roughly equal to 4 kcal. So based on a 2,000 kcal diet this would equate to a consumption of between 50 and 175 grams of protein per day. Protein intake depends on many factors including but not limited to age, sex, lifestyle, body composition, and any underlying health problems or diseases.
Protein and the Kidneys.
A high protein diet has a direct impact on the kidneys. Protein-rich diets cause the kidneys to work harder than normal. Excess protein that is not used in the synthesis of more proteins can be metabolized. This process produces urea as a toxic waste product that needs to be removed from the body. Those who suffer from kidney disease have a reduced ability to filter blood effectively, the national kidney foundation advises a consumption of 0.6-0.75 grams per kilogram of body weight.
It seems too that the type of protein may have an effect on the kidneys. The breakdown of animal-based proteins creates products that cause a decrease in pH-levels, an increase in acid load. Plant-based proteins were not found to cause such effect and in fact, a study found that supplementation with a plant-based diet causes an increase in pH-levels. The kidneys, as well as the lungs, are responsible for balancing pH-levels.
Protein and Bone health.
It is suggested by some that in order to balanced pH-levels the kidneys take calcium from the bones leading to a decrease in bone density. This idea, however, lacks much support after further studies have shown that protein-rich diets actually cause an increase in calcium absorption in the small intestine and through the release of a growth hormone known as IGF-1 cause an increase in bone density, meaning an improvement in bone health.
IGF-1 and Cancer.
As discussed before IGF-1 is a growth hormone. It is predominately active during childhood and teenage years. Its purpose is to encourage growth, it is the reason why the body grows so much during this time. IGF-1 production decrease after this time, however, a protein-rich diet can increase its production again. In simple terms, because the body is receiving such a high amount of protein it releases IGF-1 to encourage growth, the problem is that the body has already finished growing. With so much growth hormone in the body and a lack of binding proteins (proteins that can bind to it and in effect neutralize it), something has to give. IGF-1 has been linked to the development of breast cancer in women, prostate cancer in men, various other cancers and serves as an indicator of cancer development. High levels of IGF-1 increase the likelihood of cancer developing.
Plant Versus Animal Protein.
Not all protein is equal. Studies into the relationship between protein-rich diets and IGF-1 have shown that animal-based proteins increased IGF-1 levels and plant-based proteins actually decreased IGF-1 levels and increased IGF-1 binding proteins. They also observed that soy protein in large quantities (>25 grams/day) also increased IGF-1 levels modestly. The reason for this is that soy protein and animal protein have a similar composition of amino acids. When the body receives a “complete” protein (like many animal-based proteins and soy), that is, a protein that contains every amino acid in sufficient quantities. These amounts of readily available amino acids are what is thought to stimulate the release of IGF-1. Plant-based proteins, however, tend to have disproportionate levels of amino acids thus not having the same stimulating effect.
Food Preparation and AGEs.
The way you prepare your food has a great impact on how healthy it is for you. AGEs are advanced glycation end products. They are the result of a complex reaction between proteins and sugars. They can form inside your body but also can form outside the body and then be ingested. AGEs form when food is processed. Frying, grilling, roasting, including various forms of heat treatment and pressurization, can lead to the formation of AGEs. AGEs are contributors to inflammation-based diseases, diabetes and further the aging process.
The good news is that we can reduce the amount of AGEs we consume by being smart about the products we choose and the method of cooking we use. Choose food that naturally contains fewer AGEs like fruits, vegetables, fish and whole grains. Buy food that has undergone the lowest amount of processing in its preparation. Poaching, steaming, stewing and boiling generate the least amounts of AGEs. Here is a table of the glycation end products of some popular foods.
Moderation and balance seem to be the best advice to take after this small look at protein rich diets. The benefits of plant based protein diets seem to be overwhelming though. Adopting better cooking practices and selecting less processed protein sources will aid in the reduction of AGEs. The topics that I have discussed are by no means a conclusive list of the effects of a protein rich diet but highlight some of the most common topics where scientific data is available. Before adopting any diet it is recommended to consult with a medical professional.
Sources and further reading:
I suggest reading this practical guide to reducing AGEs in the diet.
“Plant based dietary supplement increases urinary pH” – John M Berardi, Alan C Logan and A Venket Rao.
“Controversies Surrounding High-Protein Diet Intake: Satiating Effect and Kidney and Bone Health” – Marta Cuenca-Sánchez, Diana Navas-Carrillo and Esteban Orenes-Piñero.