food

Leafy greens are actually a great source of calcium

Kale especially

Okay, I just finished my postgrad in nutrition and holy shit is it difficult to get any kind of straight answer out of the FDA / USDA. I'm not surprised you're confused. Secondly I'm not in the States myself, so I'm not super familiar with those guidelines and this is going to be a more general kind of answer. Third, I'm not a doctor or dietician so I can't prescribe you any kind of supplements or diet plan.

Setting aside the rampant corruption in the US food system for the moment, probably not. For a few reasons. Generally speaking, actual nutrient requirements in a population tend to follow a bell curve, where most people will be closer to the middle. RDI is set intentionally high, to cover 95% of people and reduce chances of anyone having an insufficiency. Calcium has the additional complication of having some pretty serious knock-on effects in pregnancy, so it makes some kind of sense to set the RDI high from that perspective too, because you can be pregnant without knowing. That said, the USA guidelines are pretty high compared with the rest of the world, and I have no doubt the dairy and supplement industries have something to do with that.

Regarding RDI, people tend to think the D stands for Daily. It doesn't. It stands for Dietary. The food industry doesn't do much to correct that mistake in people, however, for obvious reasons. The mg/day measurement is really meant to be used as an average over time. With most nutrients the body is clever enough to store and use them as needed, within reason. There are exceptions in, for example, pregnancy, like I mentioned above, because you're growing a whole other person. But generally speaking, it's okay to have a bit of fluctuation on a daily basis, so long as it averages out over a week or so. Your bones aren't going to instantly crumble if you're a little short for a couple days.

I do have to hedge my bets a little bit though, because there is a pretty good basis for varying guidelines across countries because of environment, lifestyle and genetic differences influencing actual biochemical calcium uptake as opposed to just dietary intake. For example, people who spend more time outside will be getting more vitamin D, and making more efficient use of the dietary calcium they do get, so they can get away with less. Vice versa if you're spending all day inside at an office job; you'll need a bit more. I'm also pretty sure USAmericans are exposed to other dietary and environmental factors that reduce calcium uptake. Sodium, for example, will reduce calcium absorption, and I -know- your food is loaded with that shit. The biochem is pretty complicated.

For practical advice, if you're really worried about it, go get a blood test, although I do realise being in the States that might be harder than it sounds. For non-animal calcium sources, dark green leafy vegetables (kale, spinach, collard greens, etc) are good, as is tofu, as well as some kinds of nuts. For some further reading, the USDA runs FoodData Central, which lets you look up the nutrient content of foods. There's also a reverse lookup of foods by nutrient content (here's calcium).

So, in summary, sort of. Your personal requirements probably aren't as high as the RDI, but there's a chance you're right at the top of that nutrient requirement bell curve. Finding out for sure means blood tests, urinalysis, food diaries and a bunch of biochem, so the RDI is intentionally set high to provide a margin of safety. It's generally not a -bad- target, but it's likely to also be pushed high by corporate interests. You probably don't need to obsess over it daily outside of some specific circumstances (e.g. pregnancy, as above). If you're eating an otherwise healthy, varied and balanced diet, getting sunlight and exercise and all that, it'll probably average out about right. If you're really worried, see a GP or dietitian.

Talk to a doctor if you can. They can test how your body is doing on calcium, tell you what you need to do to avoid kidney stones, and possibly prescribe some medication to help.