Which Protein Is Best For You, Animal Or Plant? | Body Gut Mind
Proteins, whether they come from plants or animals, are formed by combinations of 20 different amino acids. Our body can make 11 amino acids, therefore called non-essential. The remaining 9 need to be obtained from the diet and are known as essential amino acids. These are histidine, leucine, isoleucine, methionine, phenylalanine, threonine, tryptophan, and valine.
Complete vs Incomplete protein
When you hear about these terms it seems that incomplete proteins are missing something, in this case, amino acids. However, this is not totally true. All plant and animal proteins (except gelatin) contain all 9 essential amino acids. What changes is the relative proportion of the amino acids. The more a protein resembles our proteins (in terms of amino acid composition), the higher quality is considered.
- Animal-based proteins are called complete proteins because they contain greater amounts of the 9 essential amino acids.
- Plant sources with complete protein are spirulina, chlorella, hemp seeds, bee pollen, peas, soy, buckwheat, quinoa, and chia seeds.
- Incomplete sources of plant proteins are legumes (with limited amounts of methionine and cysteine), cereals (little lysine and tryptophan), vegetables, nuts and seeds (methionine, cysteine, lysine, and threonine), and seaweed (histidine and lysine).
Tip! Combine different plant proteins to make complete proteins (i.e. brown rice with lentils).
Digestibility and bioavailability
Animal proteins present higher digestibility and bioavailability. Together with proteins, animal-based foods contain saturated fats, heme-iron, vitamin D3, Omega-3 docosahexaenoic acid (DHA), vitamin B12, creatine, taurine, carnosine, and conjugated linoleic acid (CLA); all of which are not present in plant-based foods. However, the only strictly necessary compound that needs to be supplemented in a vegan diet is vitamin B12.
On the flip side, plant proteins (except soy) are less digestible and bioavailable due to the presence of fiber and phytochemicals (phytates, saponins, tannins, or trypsin inhibitors). However, these compounds have been shown to be beneficial for us. For example, they are known to improve lipid profile, regulate blood glucose levels and decrease the risk of certain cancers.
Do they have different effects on the body?
Research is showing that yes, they do.
One study performed to 85.000 women and 46.000 men health professionals in the United States, showed a correlation between higher animal protein intake and mortality; while plant protein was protective. They also pointed out that substituting animal protein, especially processed red meat, for plant protein, was associated with lower mortality.
Other studies have linked a greater intake of animal protein to high blood pressure (and high plant protein intake correlated with lower blood pressure).
While most of these studies are observational, animal studies are showing that animal protein promotes the growth of breast and liver cancer. It is thought that this happens due to an elevation of the growth hormone, estrogens, and reactive oxygen species (ROS). It is important to mention that proteins from soy and wheat did not have the same effects on tumor growth.
Okay, they seem to provide different health effects, but why?
Thanks to in vitro and animal studies, we know that plant and animal proteins induce distinct physiological and gene expression responses.
In general, there are 3 main points that we should look at: the amino acid content, the contribution from other non-protein components that come along when eating whole foods, and the impact on the gut microbiome.
1. Amino acid content
Animal and plant proteins contain different proportions of amino acids, and each amino acid has its unique physiologic effects.
Health effects from amino acids found in higher amounts in animal proteins:
BCAAs may play a unique role in stimulating muscle protein synthesis. Thus, animal-based proteins are known to be responsible for higher anabolic stimulation, compared to plant-based proteins. An exception is pea and soy protein, which contain larger amounts of BCAAs than other plant sources.
Lysine and methionine, found mainly in animal products, have been related to increase hypercholesterolemia. The contrary association has also been found: lower amounts of lysine and methionine provide preventive effect against cardiovascular disease via cholesterol regulation.
Methionine, cysteine, glycine and indigestible peptides (found in white fish, but less in red fish) may explain why rats fed with white fish (cod) proteins had a hypocholesterolemic effect, compared to rats fed with red fish (tuna) proteins.
Health effects from amino acids found in higher amounts in plant proteins:
Arginine, a non-essential amino acid found in nuts, was shown to be beneficial for blood pressure, and protective for cardiovascular diseases , therefore playing an important role in vascular health.
Glycine, also shown to play a role in lowering blood pressure.
2. Whole foods
Apart from protein, animal and plant-based foods provide different types of fatty acids, micronutrients, carbohydrates, and other bioactive components, all of which have beneficial or adverse effects.
For instance, red meat cooked at high temperatures creates heterocyclic amines, associated with higher rates of certain cancers, and other end-products that can raise blood pressure and may be the risk of type 2 diabetes.
Contrary to meat, fish is packed with omega-3 fatty acids and has been associated with reduced CVD risk and mortality.
Plants contain fiber, vitamins and minerals, and many other phytochemicals with proven health benefits (with antioxidant, anti-carcinogenic and anti-inflammatory properties).
3. Gut microbiome
Gut bacteria are involved in the formation of trimethylamine N-oxide (TMAO), a compound associated with cardiovascular disease, atherosclerosis, and neurological disorders.
TMAO is formed from lecithin, choline, and carnitine (all primarily found in animal-based products). The first step of conversion is done only by bacteria. Then, the product is oxidized in the liver forming TMAO which enters circulation. And why is this bad? Well, elevated plasma TMAO levels are related to an increased pro-inflammatory state. It is important to mention that choline can also be found in some plant-based foods.
Originally published at https://www.bodygutmind.blog on August 1, 2019.
