I will get to Tim Later in this post, but first, we should all understand that Protein is essential for good health, and numerous studies tell us that the quality AND quantity both matter. 1 Much to my surprise, two papers supporting animal-based protein consumption were published last week. Not surprisingly, one of them began this way. "A shift towards more plant-based diets promotes both health and sustainability." Strange, considering they go on to question the health-promoting aspects of plant proteins compared to animal proteins. Perhaps they were able to obtain grant money for attempting to uphold the politically correct notion that meat is rotten for us and the planet. Additionally, the peers who review scientific papers often promote groupthink, which makes obtaining grants and having data published that may refute their currently held beliefs difficult. Nevertheless, I am happy these studies were able to see the light of day.

Study Number One

Today's first study was high-quality because the researchers controlled the nutrient intake by providing much of the food. The researchers noted the lack of controlled trials addressing the nutritional effects of replacing animal proteins with plant proteins. Therefore, they examined the impact of replacing animal proteins with plant proteins on healthy adults' critical vitamin and mineral intake and status. They broke the participants into three groups. One group ate 70% of their protein from animal sources and 30% from plants. Therefore, they were named the ANIMAL group. The second was called the 50-50 group because 50% of their protein was distributed evenly between animals and plants. The Last group got 70% of their protein from plants and only 30% from animals and were called the PLANT group. The plant-based proteins came from cereal products, vegetable dishes, including peas, lentils, chickpeas, tofu, fava beans, nuts, almonds, seeds, and plant-based dairy substitutes. Energy, carbohydrate, and total fat intake did not differ between the groups at the end of the intervention. However, fiber intake in the PLANT and the 50/50 groups were higher than that in the ANIMAL group. 

 Lower vitamin B-12, zinc, and iodine intake and status and risk for deficiency have been reported in vegan and, to some extent, in vegetarian diets. You can read my post on B-12 here. For this reason, the researchers decided to look into the B-12, zinc, iodine, and other common nutrient statuses of their subjects. Baseline and endpoint vitamin B-12, iodine, iron, zinc, and folate were measured. The participants ate their respective diets for twelve weeks. Additionally, participants were advised to discontinue dietary supplements and herbal or other natural remedies two weeks before the trial. Fortified foods were not used, except for the bread, which had added iodized salt. 

 No differences emerged in vitamin C intake among the diet groups. In addition, the iron and folate status were similar in all of the groups, despite the higher amount in the PLANT and 50/50 diets. Iodine was normal in the ANIMAL group, lower in the 50/50 group, and lowest in the PLANT group. Inadequate or deficient iodine can result in thyroid conditions ranging from hypothyroidism to enlargement of the thyroid called goiter. Significant decreases in B-12 intakes were seen in the 50/50 and PLANT groups, so even partial restriction of animal-derived foods affects B-12 intake. Since plants don't contain B-12, these results are unsurprising. To that end, three participants suffered from low B-12 status after the 12 weeks. This finding reflects the EPIC-Oxford study, where omnivores had the highest B-12 intake, followed by progressively lower intakes by fish-eaters, Lacto-Ovo vegetarians, and vegans. 2

The researchers conclude that switching to a plant-based protein source is less healthy than once believed and can lead to nutrient deficiencies. 

Study Number Two

The next study, conducted over twenty years in Tuscany, Italy, was aptly named the InCHIANTI study. They had over 1,100 participants with a mean age of 75. They used food frequency questionnaires, so the study should be viewed as low-quality. There were 811 deaths, 292 from cardiovascular disease and 151 from cancer. The researchers looked at protein sources in the diet and concluded that animal protein was associated with lower all-cause mortality. They also concluded that plant protein did not affect longevity. 3

Protein Quality

All protein is made from amino acid building blocks. Essential amino acids are the ones we need in our diet because we can’t manufacture them. The nine essential amino acids include phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, and lysine. The mnemonic PVT TIM HaLL (Private Tim Hall) is a commonly used device to remember these amino acids as it includes the first letter of all the essential amino acids. 4 Proteins from animal sources like eggs, milk, meat, fish, and poultry provide the highest quality food sources because they always contain all of the amino acids humans need, so this is why they are called complete proteins. Private Tim Hall will always show up when we eat animal-based proteins. This is not always true for plant-derived proteins.

 Compared to animal-based proteins, plants require different amino acids than animals, so animal-based proteins are a safer bet. 5 We CAN get all of the amino acids we need from plants, but it is more complicated. In addition, the extra nutrients that come along with animal-sourced proteins make them generally a superior choice. Either way, I like to avoid processed foods as a rule, including protein powders. We evolved eating whole foods, so when we process them, oftentimes, critical nutrients are removed. 

How Much Protein Do We Need?

The current recommendation for protein intake is 0.8 g/kg. However, the definition of the protein RDA has been criticized as too low. It reflects the minimal amount of protein required to prevent deficiency rather than an amount that may allow for optimal health. Many professional organizations recommend protein intakes double the current RDA. The Academy of Nutrition and Dietetics recommends between 1.2 and 2.0 g/kg. The International Society for Sports Nutrition also recommends protein intake at levels higher than the RDA for physically active individuals from 1.4 to 2.0 g/kg. 6 Lastly, since it becomes increasingly difficult to absorb dietary protein as we age, experts in the field of protein and aging recommend a protein intake between 1.2 and 2.0 g/kg or higher for elderly adults. 7 since one kilogram is equal to 2.2 pounds, to convert the RDA's I just mentioned to grams/pound, halve them. So 2g/kg is roughly 1 g/lb.

I have written before about sarcopenia, which is a condition of decreasing muscle mass as we age. Sarcopenia leads to several adverse health outcomes, especially later in life, including loss of function, disability, frailty, limitation of independence, increased insulin resistance, fatigue, falls, arthritis, and early death. Adequate intake of quality protein is the best way to prevent the condition.

What You Can Do Today

The bottom line is that we don't want to be deficient in ANY amino acids because we will break our muscle tissue down to find the one we need. The condition of muscle breakdown is called a catabolic state. We want to be in a muscle-building state, also known as an anabolic state. A healthy person can eat up to 35% of their calories as protein, not that we have to. For a 2000 calorie diet, this translates to 175 grams of protein. People with kidney disease should not consume extra protein because damaged kidneys are prone to more damage when challenged with extra protein. But extra protein does not damage healthy kidneys. My personal goal is about 1 gram of protein per pound, which, for me, is 150 grams per day.

As I have mentioned many times before in various posts, tracking nutrition is free and easy with any number of apps like My Fitness Pal or Cronometer. You don't need to track your nutritional intake forever, but one week to one month of tracking will give you a general idea of your nutritional status. Remember: Protein is essential for good health, and numerous studies tell us that the quality AND quantity both matter. So please pay attention to the kind of protein you consume, and make sure you are getting enough of it.