Eating below the minimum RDA of 0.8 g/kg is unlikely to cause diseases of protein deficiency. The RDA minimum is fairly generous to allow for a certain margin of error. Most of the studies cited by https://www.ncbi.nlm.nih.gov/books/NBK234922/ indicate that 0.6 g/kg is likely a sufficient reference, and that a recommendation of 0.75 g/kg allows for enough confidence to cover individual variation. There was one study cited which found a 0.8 g/kg minimum, but most of the rest found that lower values should be sufficient; it sounds like 0.8 was picked just to be on the safe side.
> At 220# that means 80-120g protein as a minimum. That's a fair amount, and far more than you're likely to get from vegetarian sources at the time alone.
I doubt that most Roman soldiers were 220#. The minimum height requirement was 5'5", and estimates are that the average height was 5'7".
> There's also a minimum amount of essential fatty acids to consider... at the time it's not like they had canola oil.
There's a certain vegetable oil that Rome and Italy are quite well known for.
I'm with you on being skeptical that they were vegetarian, but I think you're overstating the requirements a little bit. I think it's fairly likely that they ate a fairly low meat diet just due to the logistical difficulties of obtaining fresh meat or carrying preserved meat.
The word "linoleic" derived from the Greek word linon (flax). Oleic means "of, relating to, or derived from oil of olive" or "of or relating to oleic acid" because saturating the omega-6 double bond produces oleic acid.
So protein only constitutes 12% or less of their caloric source. Just about all food have some proportion of protein. Cooked oatmeal is 16% protein by calories.
edit: could include fish, depending on the location.
It’s doesnt matter if a vegetable is considered a carb, that can still have a significant amount of protein.
Some that fall in that category include: broccoli, spinach, asparagus, peas, Brussels sprouts, mushrooms, (as others has said legumes).
In my own regimen when I was trying to maintain ketosis while eating vegitarian I ate a lot of seeds and nuts, they of course have carbs but significant amounts of fat/protein. Also I had tons of coconut oil and coconut butter (about the best fat you can get from an energy perspective medium chain triglyceride).
They may not have had canola, but olive oil was a big staple, and that’s an example of a non-meat that packs significant calories and fat.
For vegetable sources, they were referred to as barley-eaters and barley is 12% protein.
The article says legionnaires and gladiators were eating 5000-6000 calories daily, with 78% from primarily wheat and barley. An average ancient whole wheat would probably be somewhere near 15% protein by weight. Daily consumption of those grains even on the low end of their estimates would contain well over 100g of protein.
Likely. Guys like Brian Shaw eat 10-12k kcals a day but they are walking around near 400lbs, amateur and semi-pro male powerlifters and oly lifters will eat 3-6k for maintenance and lean bulk depending on their size and weight class and that's just an hour or two of lifting 3-5x a week.
They'd have been shorter and likely leaner so I'd say 3k-4k kcals is a good guess based on my experience in strength sports and martial arts.
"The legionnaire's daily ration consisted of 78% carbohydrates, mainly from wheat or barley. This diet has the advantages to provide slowly absorbed carbohydrates, to be provide high energy, and to be easily digestible. It provided good intestinal ballast, and was able to restore the energy reserves of the organism (Fornaris and Aubert, 1998; Lemon et al., 1992). The best fighters in the ancient world were essentially vegetarian."
78% from carbs != vegetarian. by their measures, I'm pretty sure most people are vegetarian.
That Plinius with his historical revisionism. Calling gladiators barley-eaters is obvious propaganda from the vegetarian lobby of ancient Rome.
This is suspected to be part of the reason for the neotenic expression of blond hair and blue eyes that emerged in Scandinavians, as you would normally get enough vitamin D from meat sources, so the evolutionary pressure for very fair skin is presumed to have come from the lower strata of society trying to live off grains and other vegetables while getting very little sunlight.
There's also a minimum amount of essential fatty acids to consider... at the time it's not like they had canola oil. So there was definitely animal products in their diets. Revisionist theories in order to support a vegetarian agenda are pretty annoying to me. A lot of it doesn't even pass a common sense sniff test.
IIRC Barley + Lentils can give you a complete protein profile, and it's possible that maybe 1/3-1/2 of their protein intake was from non-meat sources. But I seriously doubt that even a significant minority were abstaining from meat.