Calcium in milk is not absorbable is a concern when it comes to calcium supplements, doesn’t it? While milk is rich in calcium and has been considered as a good source of calcium for those somehow not eating non-vegetarian food. The lower metabolic cost gained by human body from milk, compared with that from other sources of calcium such as bones, antlers, and teeth has resulted in an overall belief that unless the body absorbs more nutrients than what it normally does then the rest must be thrown out or secreted out. The fact remains that calcium in milk diet will lessen the need for calcium consumed from dairy products as bones are well satisfied with softer tissues available from flesh of animals.
Calcium In Milk Is Not Absorbable
The current daily recommended allowance for calcium for most adults is 1,000 to 1,200 milligrams. However, plant-based health experts believe these requirements are high for a simple reason: a diet high in animal protein has a high excretion rate, which means you are forced to consume more calcium to make up for the inherent calcium excretion. When following a whole-food, plant-based diet (that is also low in sodium and caffeine), calcium excretion rates are much lower, which logically means that a plant-based eater’s calcium intake can also be much lower.
How much lower? A study published by the American Journal of Clinical Nutrition showed that “individuals with low, but nutritionally adequate, intakes of sodium and protein may have calcium requirements as low as 500–741mg/day.”
Can I Really Get Enough Calcium Eating Just Plants?
Like iron, magnesium, and copper, calcium is a mineral. It is found in the soil, where it is absorbed into the roots of plants. Animals get their calcium by consuming these calcium-rich plants. So even though we are all conditioned to believe that calcium comes from milk and dairy products, the real source of calcium richness is the earth. No wonder that a whole-food, plant-based diet has plenty of calcium.
A varied diet of starches, vegetables, and fruits (without dairy) has sufficient calcium to meet our needs. If you eat a relatively low-calcium diet, your body will adjust. Studies show that when fed a relatively low-calcium diet (415 mg/day), our intestines become more efficient at absorbing calcium, and our kidneys conserve it better. Equally, when overfed with calcium (1,740 mg/day) our bodies adjust as well: our intestines block the calcium absorption, while our kidneys eliminate more. This is an example of how our bodies protect us: if not eliminated, the excess calcium would get deposited in our soft tissues (heart, kidneys, muscles, and skin), making us vulnerable to illness and even death … a true testament to how smart our bodies really are!
So your needs are met. Always.
At the end of the day, the “disease” of calcium deficiency from a calorically sufficient natural whole-food plant-based diet is nonexistent.
How Much of the Calcium I Eat Is Actually Absorbed?
The amount of calcium we ingest may be less important than how much we actually absorb. For example, 1 cup of milk contains about 300 mg of calcium. But only about 30% of it (90 mg) is actually absorbable, and thus bioavailable (available to our bodies).
Let’s compare the calcium content and absorption rate of cow’s milk versus some plant-based alternatives:
- The calcium in firm tofu has about the same absorption rate as dairy products, hovering around 31%. And while ½ cup of tofu yields the same amount of calcium as 1 cup of milk (300 mg), it contains more protein, far less saturated fat, and about a tenth of the sodium.
- Calcium-intense vegetables like Chinese mustard greens enjoy absorption rates of around 40%. In terms of calcium content, 1/2 cup of these cooked greens will give you as much calcium as one glass of milk.
- One cup of bok choy, 1½ cups of kale, or 2 cups of broccoli contain the same amount of calcium as a glass of milk, due to their much better calcium absorption rate (in the 50–60% range! )
What Factors (or Foods) Make Me Lose Calcium?
Many factors contribute to calcium loss, from age (older people lose more calcium) to vitamin D status (people who test low for vitamin D3 tend to lose more calcium) to the concurrent contents of your intestines. Sodium, protein, and caffeine play primary roles in calcium loss.
- Sodium: Sodium is our biggest enemy when it comes to calcium loss. For each 1000 mg of sodium (2,500 mg of table salt) excreted by the kidneys, about 40–60 mg of calcium goes with it.
- Protein: As the intake of dietary protein increases, so does the urinary elimination of calcium. So when you double your protein, your calcium loss through urination increases by 50%.
The propensity of protein to cause calcium loss is particularly interesting when it comes to dairy products, which have always been considered as one of the best calcium sources. You lose 1/3 of the calcium you get from milk and over 2/3 of the calcium you get from cheeses.
- Caffeine: Caffeine also seriously affects the body’s ability to retain calcium, as it acts as a diuretic and pulls calcium out from the body.
In stark contrast, many leafy green vegetables provide lots of easily absorbed calcium without causing calcium loss!
Can’t I Just Fix Everything by Taking Calcium Supplements?
Even though studies show that supplementing with calcium can reduce the risk of fractures by 10% (hip fractures excluded), doing so can also increase our chances of cardiovascular disease and strokes, cause kidney stones, and induce gastrointestinal distress.
According to the results of a recent randomized, double-blind, placebo-controlled study of over 36,000 post-menopausal women, “Calcium supplements with or without vitamin D are associated with an increased risk for MI (myocardial infarction) and stroke, and this risk appears to apply across subgroups defined by important baseline characteristics. These findings suggest that targeted prescription of calcium supplements to specific population subgroups, such as younger people and those with low dietary calcium intake, should not be endorsed.”
But If We Don’t Drink Milk or Take Calcium Supplements—What Happens to Our Bones?
A recent study addressed this very important question, comparing the bone mineral density of long-term vegans versus omnivores. The results were astounding; even though the vegans have vastly lower dietary calcium and protein intakes, they enjoyed the exact same bone density as their meat-eating counterparts.
In conclusion, you don’t need dairy or supplements to get enough calcium (in fact they may be a hindrance rather than a help). As long as you eat a calorically sufficient whole-food, plant-based diet that drastically reduces or completely eliminates added sodium, you’ll get all the calcium you need.
Is Drinking Milk The Best Way For People To Incorporate Calcium Into Their Diet?
“Calcium absorption from milk and other dairy products is about 32%, whereas calcium absorption from vegetables ranges from about 5% in spinach to more than 60% in some brassica vegetables such as broccoli. However, the high bioavailability of calcium from some vegetables cannot overcome their low calcium content. One would have to consume 2 1/4 cups of broccoli to obtain the same amount of calcium absorbed from one cup of milk.”
“The largest source of dietary calcium for most persons is milk and other dairy products, which accounts for 72% of the calcium in the US food supply. Sixty-five percent of the dietary calcium intake in children in the United States is supplied by dairy products. Drinking three 8-oz glasses of milk per day will achieve the recommended adequate intake of calcium in children 4 to 8 years of age, and four 8- to 10-oz glasses of milk will provide the adequate calcium intake for adolescents… It is important to note that there is relatively little difference in the calcium content of reduced-fat dairy products compared with whole milk–derived products…
Most vegetables contain calcium, although at relatively low density. Thus, large servings are needed to equal the total intake achieved with typical servings of dairy products… Calcium supplements are another alternative source, but these products do not offer the benefits of other associated nutrients, and compliance may be a problem.”
“Bioavailability, the degree to which the intestinal system absorbs calcium, depends on the overall level of calcium in a food and the type of food being consumed. Calcium in foods such as milk and milk products is highly bioavailable, meaning that it is easily absorbed…
However, calcium in foods high in oxalic acid (such as spinach, sweet potatoes, and beans) or phytic acid (such as unleavened bread, raw beans, seeds, and nuts) may be poorly absorbed. Oxalates in particular are strong inhibitors of calcium absorption. As a result, additional servings of certain calcium-rich foods are needed to compensate for their low bioavailability…
High bioavailability is one of the reasons that the NICHD describes low-fat and fat-free milk and milk products as the best dietary source of calcium.”
“Dairy products are not the best source of calcium as they cause calcium losses at the same time as increasing calcium intake. A third of the calcium absorbed from milk and more than two thirds of the calcium absorbed from cheese is wasted this way. In contrast, low oxalate green leafy vegetables such as kale and spring greens provide plenty of well absorbed calcium while at the same time reducing calcium losses. Calcium supplements lie in between in terms of their effect of retained calcium.”
“Dairy products contain nutrients, including protein, sodium, and, in some cases, supplemental vitamin D, all of which influence calcium balance and bone mineralization and alter or negate the effect of dairy calcium in the body’s mineral economy. Animal protein and sodium, in particular, tend to increase calcium excretion…
We found no evidence to support the notion that milk is a preferred source of calcium… Although milk and other dairy products are reliable sources of calcium, many factors affect the availability and retention of the calcium from these products. For example, the calcium in dairy products is not as well absorbed as that in many dark green leafy vegetables but has an absorption fraction similar to that of calcium supplements, calcium-enriched beverages, calcium-set tofu, sweet potatoes, and beans. Dairy products… clearly increase the urinary excretion of calcium as a result of their increased sodium, sulfur-containing amino acid, and phosphorus content.”
“Milk is actually only one of many sources of calcium, and there are some important reasons why milk may not be the best source for everyone…
Many people have some degree of lactose intolerance. For them, eating or drinking dairy products causes problems like cramping, bloating, gas, and diarrhea. These symptoms can range from mild to severe… Many dairy products are high in saturated fats, and a high saturated fat intake is a risk factor for heart disease…
High levels of galactose, a sugar released by the digestion of lactose in milk, have been studied as possibly damaging to the ovaries and leading to ovarian cancer… In a Harvard study of male health professionals, men who drank two or more glasses of milk a day were almost twice as likely to develop advanced prostate cancer as those who didn’t drink milk at all.”