Animal Protein vs Plant Protein

There are many who believe that eating a plant-based diet will leave them protein deficient.

It is easy to understand why many would believe this is the case. Below is a list of food ranked by the PDCAAS (protein digestibility corrected amino acid score), which is the measure of protein quality used by the World Health Organization. The list comes from Wikipedia.

1-1.21 cow's milk
1-1.18 eggs
1 casein (milk protein)
1 soy protein
1 whey (milk protein)
0.99 mycoprotein
0.92 beef
0.91 soy
0.87 Sacha Inchi Powder
0.82 pea protein isolate
0.78 chickpeas and soybeans
0.75 black beans
0.74 tubercles
0.73 vegetables

https://en.wikipedia.org/wiki/Protein_Digestibility_Corrected_Amino_Acid_Score

Any food with a PDCAAS of 1.0 is a "perfect protein." In 1990, the FAO/WHO decided that "proteins having values higher than 1.0 would be rounded or 'leveled down' to 1.0 as scores above 1.0 are considered to indicate the protein contains essential amino acids in excess of the human requirements."

As you can see on the list, there are plenty of vegan options on that list that are equivalent to animal products. For example, rather than eat beef (0.92) you can eat soy (0.91). Rather than drink whey protein (1.0), you can drink soy protein (1.0).

However, someone eating, say, black beans, may believe that he would become protein deficient because black beans have a PDCAAS of 0.75.

However, people generally don't eat the same food all the time. A key limitation of the PDCAAS is that it doesn't take into consideration the fact that if you eat two or more foods with low PDCAAS, the combination of these foods can create a perfect PDCAAS of 1.0.

This concept is explained in the article: "[G]rain protein has a PDCAAS of about 0.4 to 0.5, limited by lysine. On the other hand, it contains more than enough methionine. White bean protein (and that of many other pulses) has a PDCAAS of 0.6 to 0.7, limited by methionine, and contains more than enough lysine. When both are eaten in roughly equal quantities in a diet, the PDCAAS of the combined constituent is 1.0, because each constituent's protein is complemented by the other."

Should we worry about protein deficiency? Is anyone protein deficient?

The video below by Dr Michael Gregor shows that statistically speaking, 97% of Americans are deficient in fiber whereas only 3% of Americans are deficient in protein. For the average person, getting enough fiber is far more of a concern than getting enough protein. Just about everyone gets more than enough protein.

Soy Milk is Healthy

There's nothing wrong with soy milk. The studies show that soy reduces the risk of prostate cancer in men, and in women it reduces the risk of breast cancer. The cancer risk reduction is caused by the phytoestrogens in soy. The scare that phytoestrogens feminize men is also overblown given that the affix "phyto-" means "plant" and plant estrogens have weak to no effect on humans. It is animal estrogen such as estradiol in dairy milk that has been shown to reduce testosterone levels in men, and there are many studies that suggest dairy milk may increase prostate cancer risk although this is not conclusive. Bottom line is if you're really concerned, just drink almond milk.

https://www.ncbi.nlm.nih.gov/pubmed/20378106

https://www.ncbi.nlm.nih.gov/pubmed/19496976

Does Soy Phytoestrogen Give You Manboobs?

I used to avoid soy because I was scared of its phytoestrogen content. However, after looking into the issue in more detail, I now have no issues with soy. I still don't like the taste of soy milk, so when I order coffee I normally opt for a long black (or Americano) or a latte with almond or coconut milk. However, not all cafes have almond milk or coconut milk, and a long black has zero calories and is often very hot, so sometimes I opt for a soy latte. Vegan meat also tends to use soy protein, although many now use pea protein, e.g. Beyond Meat Beast Burger.

In terms of protein powder, I get all my protein powder from BulkNutrients.com.au, which I find is the best source of protein for Australians. At Bulk Nutrients, pea protein is the cheapest protein powder of all, cheaper than soy protein and whey protein, and the cost savings are even better if you buy in bulk. (If you live outside Australia, consider buying pea protein from iHerb, which has international shipping. They also have a great selection of vitamins.)

The bottom line is to not worry too much about soy as studies show that in moderation it has no impact on hormones. Even in extreme doses soy seems to have no impact. If you like the taste, work it into your diet, but remember there are many other vegan protein sources such as beans, nuts, and seeds. I've been eating soy in moderation for a few months now and have noticed no manboobs.

Below is a collection of YouTube videos on the topic.