There are many popular myths surrounding calcium and dairy milk, that might make people hesitate when considering a vegan diet. Most of these are based out-dated science, advertising from the diary industry, and growing up during a time in history when the dairy industry had a strong influence on government policies.
Dairy consumption has also been linked to higher risk for various cancers, especially to cancers of the reproductive system, especially prostate and breast cancers. This is most likely due to increases in insulin-like growth factor (IGF-1), which is found in cow’s milk. Case-control studies in diverse populations have shown a strong and consistent association between serum IGF-1 concentrations and prostate cancer risk. In one study, men with the highest levels of IGF-1 had more than four times the risk of prostate cancer, compared with those who had the lowest levels. In the Physicians Health Study, 21,660 participants were tracked for 28 years, and researchers found an increased risk of prostate cancer for those who consumed 2.5 servings of dairy products per day as compared with those who consumed ≤0.5 servings a day.
In addition to increased levels of IGF-1, estrogen metabolites are considered risk factors for cancers of the reproductive system, including cancers of the breasts, ovaries, and prostate. Estrogen metabolites can affect cellular proliferation, causing cells to grow rapidly and aberrantly, which can lead to cancer growth. Consumption of milk and dairy products contributes to the majority (60-70 percent) of estrogen intake in the human diet.
In a large study that included 1,893 women from the ‘Life After Cancer Epidemiology Study’ who had been diagnosed with early-stage invasive breast cancer, as little as 0.5 servings a day of high-fat dairy product consumption was associated with significantly increased mortality rates. Estrogenic hormones reside primarily in fat.
In a Swedish study, consumption of lactose and dairy products was positively linked to ovarian cancer. A similar study conducted by the Iowa Women’s Health Study, found that women who consumed more than one glass of milk per day had a 73% higher chance of developing ovarian cancer than women who drank less than one glass per day. While more studies need to be done, it’s possible that this link is due to the breakdown of the milk sugar lactose into galactose, a sugar which may be toxic to ovarian cells.
Insulin-dependent (type 1 or childhood-onset) diabetes is linked to consumption of dairy products in infancy. A Finnish study of 3,000 infants in with genetically increased risk for developing diabetes showed that early introduction of cow’s milk increased susceptibility to type 1 diabetes. In a study of 142 children with diabetes, 100% had high levels of an antibody to a cow’s milk protein. The American Academy of Pediatrics observed up to a 30% reduction in the incidence of type 1 diabetes in infants who avoided exposure to cow’s milk protein for at least the first three months of their lives.
Calcium is necessary for bone health, but the benefits of calcium intake do not exist after consumption passes a certain threshold (more isn’t always better). Consuming more than approx. 600 mg per day (easily achieved without dairy products or calcium supplements) does not improve bone integrity, and there have been mixed results from clinical research, with some studies raising doubts about the benefit of dairy products for bone health. Here are some examples:
*Harvard Nurses’ Health Study: 72,000 women followed for 18 years, showed no protective effect of increased milk consumption on fracture risk.
*According to a 2005 review published in Pediatrics, milk consumption does not improve bone integrity in children.
*Arch Pediatr Adolesc Med. 2012: Researchers concluded that dairy products and calcium do not prevent stress fractures in adolescent girls.
To decrease the risk of osteoporosis:
*Reduce the sodium intake in your diet (77% of dietary sodium comes from processed foods)
*Increase your intake of fruits and vegetables (they contain bone-nourishing nutrients such as vitamin K, vitamin C, folate and potassium)
*Ensure adequate calcium intake from plant foods such as kale, broccoli, and other leafy green vegetables and beans.
*Include soy in your daily diet (isoflavones protect bones)
*Reduce caffeine and alcohol intake
*Get some sunlight, and monitor vitamin D levels
Maintaining healthy calcium levels
When it comes to calcium status, calcium excretion is more important than calcium intake or absorption. Calcium excretion accounts for 74% of calcium status, while calcium intake only accounts for 11% and calcium absorption for 15%.
In adult women, every gram of sodium they consume that is in excess of the daily requirement, is estimated to increase the rate of bone loss by 1% per year.
Good whole-plant food sources of calcium:
One cup of cooked kale, 2⁄3 cup of tofu, or 1 and 2⁄3 of a cup of broccoli provide the same amount of absorbable calcium as 1 cup of cow’s milk.
Some good plant sources of calcium include hard tofu, almonds, unhulled tahini (sesame seed paste) and green leafy vegetables such as Kale and Asian greens (e.g. bok choy, Chinese broccoli).
Other useful sources can include soybeans, fortified foods (e.g. nondairy milks, tofu and juice- check labels), oranges, figs, organic blackstrap molasses, dried mango, pink grapefruit, and chia seeds.
Calcium absorption is particularly good from broccoli, bok choy, napa, cabbage, watercress, mustard and turnip greens. Absorption is reasonable from collard greens but poor from spinach and swiss chard).
Lifestyle/health factors that increase your calcium intake needs:
Diarrhoea, bed rest, lack of exercise, depression, ageing, diabetes, bone fractures, high blood pressure, low blood sugar, intestinal malabsorption, achlorhydria, pregnancy, lactation, hypothyroidism, kidney disease.
Using anticonvulsants, salicylate drugs like aspirin, corticosteroids, antacids, loop diuretics, tetracycline and fluoroquinolone antibiotics, aminoglycosides like gentamicin and neomycin, digoxin, doxycycline, fluoride, mineral oil, methotrexate.
Deficiency is associated with:
Agitation, irritability, ADHD, back pain, brittle finger nails, delusions, depression, eczema, hyperactivity, salt-sensitive high blood pressure, insomnia, limb numbness, menstrual cramps, muscle cramps, osteoporosis, periodontal disease, rickets, sciatica, tooth decay and loss.