Vitamin C and calcium: daily needs and food sources
Vitamin C: daily needs and food sources
The daily need of vitamin C (ascorbic acid), depending on the labor intensity and the age is 64-108 mg for men and 55-79 mg for women.
Scientists have concluded that 1200 mg of vitamin C per day helps to prevent falling ill during flu epidemics. It is actually sufficient to take only 100 mg, but after an appearance of the first signs of the disease, the dose should be increased up to 1 g.
For those who smoke a pack of cigarettes per day (20 pieces) the dose should be increased by 20% and for those who smoke more than a pack – by 40%. Those who drink a lot of beer, wine, whiskey or other alcoholic drinks it is also required to increase the consumption of vitamin C.
Diabetes patients also require higher doses of vitamin C – 1 g on average per day, due to the difficulties with its transport across the cell membranes. Diabetes contributes to the development of multiple sclerosis, but large doses of vitamin C to help deal with that.
Many vegetables and fruits: rose hips, black currants, sweet pepper, parsley, fennel, cabbage, sorrel, tomatoes, chestnuts, onions, spinach, oranges, lemons, strawberries, etc. – are rich in vitamin C. Walnut contains great amount of vitamin C – about 3000 mg% of ascorbic acid. One of the vitamin C sources available for people from northern countries during winter is sauerkraut, which contains a large amount of ascorbic acid.
The vitamin C is also can be found in many herbs: barberry, birch, hawthorn, cranberries, veronica, geranium, knot-grass, oregano, St. John's wort, goldenrod, willow-herb, clover, nettle, burnet, hazel, lemongrass, burdock, toadflax, alfalfa , lady's mantle, pigweed, coltsfoot, lungwort, mint, sea buckthorn, dandelion, aspen, primrose, plantain, motherwort, rowan, black chokeberry, goutweed, pine, asparagus, cottonweed, thistle, violets, chicory, bur-marigold, wild cherry, blueberry, rose, dead-nettle (3).
The Table 1 (Natural food-Fruit Vitamin C Content, 2001) provides information on the vitamin C content in some products:
Vitamin C content in some products
Vitamin C is destroyed during food storage. In springtime vitamin C content in raw vegetables is 45% less than in the fall. Large amounts of the vitamin (20-40%) are destroyed by heat treatment. Long-term storage of prepared food also reduces vitamin C content.
Calcium: daily needs and food sources
The daily need for calcium for adults is 0.8 grams; for pregnant and breastfeeding women – 1 g per day. The need for calcium increases for athletes, for people whose work is related to occupational hazards, and for those who is suffering from excessive sweating and is being treated by glucocorticoid and anabolic steroids.
Calcium absorption depends on the amount of fats, fatty acids, proteins, calciferol, magnesium, and phosphorus in the diet.
Calcium is absorbed from the intestines as complexes with fatty and bile acids. The optimal ratio is 10-15 mg of calcium per 1 g of fat. The absorption of calcium is aided by sufficient content of unsaturated fatty acids. Insufficient and excess fat, especially one rich in saturated fatty acids impair calcium absorption. An excess amount of fats in the diet leads to the formation of nonabsorbables.
Insufficient amount of protein in the diet also affects the assimilation of calcium. Calcium absorption in the intensities is disrupted in case of calciferol deficiency, which leads to the use of bone calcium (Dietary Reference Intakes for Calcium and Vitamin D, 2010).
The best ratio of calcium to magnesium in the diet is 1:0.6. Following products are close to this ratio: sardines (1:0.5), Atlantic herring (1:0.5), eggplants (1:0.6), cucumbers (1:0.6), lettuce (1:0.5), garlic (1:0.7), beans (1:0.7), pears (1:0.6), apples (1:0.6), grapes (1:0.6) raspberries (1:0.5) and white mushrooms (1:0.5).
The best ratio of calcium to phosphorus for adults is 1: 1.5. Ratio close to that is in cheese (1:1.6), cucumbers (1:1.8), garlic (1:1.7), grapes (1:1.8), etc.
The absorption of calcium in the bowels is hindered by foods rich in oxalic acid – sorrel, rhubarb, spinach, beets, chocolate (Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride, 1997).
Calcium is being lost during heat treatment. The losses will be negligible in case the water, in which vegetables are cooked, has further use (e.g., gravy or broth).
Kale, turnip greens, beans and almonds are very rich in calcium. However, the use of chemical fertilizers in the cultivation of vegetables reduces the content of this mineral.
Calcium is contained in many foods (cereals, meat, fish), but it is not easily assimilable. For example, the body can absorb only 13.4% of the calcium contained in carrots. It is necessary to eat 700 grams of carrots to get 1/4 of the daily need of calcium. Calcium is easily absorbed from lettuce, but its content is low.
The most digestible calcium is contained in milk and dairy products (excluding butter) in combination with fruits and vegetables. Goat milk is richer than cow milk. To meet daily need it is necessary to drink 0.5 liters of milk or to eat 100 grams of cheese.
The presence of vitamin D in the diet is also essential for calcium absorption. It is contained in milk, liver, eggs, lettuce (Dietary Reference Intakes for Calcium and Vitamin D, 2010).
(2010). In Dietary Reference Intakes for Calcium and Vitamin D. Retrieved Jan. 26, 2016, from http://iom.nationalacademies.org/~/media/Files/Report%20Files/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Vitamin%20D%20and%20Calcium%202010%20Report%20Brief.pdf
(1997). Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride Washington, D.C, National Academy Press.
(2001). In Natural food-Fruit Vitamin C Content. Retrieved Jan. 26, 2016, from http://www.naturalhub.com/natural_food_guide_fruit_vitamin_c.htm