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Vitamins D And K And Magnesium: A Must For Osteoporosis Prevention

The roles of vitamins D and K and magnesium (and meaningful exercise) have been underestimated because of a widespread singular focus on calcium.

This is part of the problem in curbing the incidence of osteoporosis according to a Canadian manufacturer of supplements.

An ideal osteoporosis prevention program has more than just calcium. It will also include:

  • 1,200-1,500 mg calcium
  • 800-5,000 IU of vitamin D
  • 120 ug Vitamin K
  • 420 mg of Magnesium
  • 1.5-3 mg Boron

This wonderful blend of vitamins and minerals is rarely found in calcium tablets but can be found in some food-based supplements and in a well-balanced diet.

Recommended Amounts

The above calcium and vitamin D targets are recommended by Osteoporosis Canada and the National Osteoporosis Foundation.

The vitamin K and magnesium targets are the upper levels recommended within the Reference or Recommended Daily Intake (RDI) followed in the United States and Canada.

There is no RDI for Boron but 1.5-3 mg is generally considered adequate. Strontium should also be considered as an element within your bone-building program.

Vitamin D3

Vitamin D3 is essential in an osteoporosis prevention program because it helps us to absorb calcium.

The Osteoporosis Society of Canada recommends that women over 50 get a minimum of 800-2,000 IU daily, which is almost impossible to achieve from sunlight in the northern part of the U.S. and in Canada.

Numerous studies have shown that over 70% of Americans and Canadians are vitamin D deficient in the winter.

Opinions on the optimal vitamin D dosage range from 1,000 IU to 5,000 IU a day in the winter. The best way to determine if the dosage is sufficient is to have an annual vitamin D blood test and then adjust the vitamin D dosage until the target blood level has been attained.

Studies have shown that vitamin D3 is much more effective than vitamin D2 at assisting with calcium absorption. Vitamin D3 is used to fortify cow's milk while most soy beverages are fortified with Vitamin D2.

The cost of six months supply of 5,000 IU vitamin D is approximately $7.

There is a wide margin of safety in vitamin D supplementation, with no evidence of vitamin D side effects below 10,000 IU per day. Supplements may be taken at any time of day.

Vitamin D And Sunlight

Research shows that we can no longer rely on 15 minutes in the sun to get all the D we need to prevent osteoporosis. Vitamin D is produced naturally by our skin when we are exposed to the ultraviolet radiation from sunlight.

Five to ten minutes of sun exposure on arms and legs or face and arms three times weekly between 11:00 am and 2:00 pm during the spring, summer, and fall at 42 degrees latitude should provide a light-skinned individual with adequate vitamin D.

It can also allow storage of excess Vitamin D for use during the winter, with minimal risk of skin damage.

This is not true at higher latitudes. In latitudes around 40 degrees north (Boston is 42 degrees north), there is insufficient UVB radiation available for vitamin D synthesis from November to early March.

Ten degrees farther north (Edmonton in Canada) this "vitamin D winter" extends from mid October to mid March.

In addition to limitations at higher latitudes, we must also consider that:

  1. The skin's ability to produce vitamin D drops with age, putting men and women over the age of 50 at particular risk.
  2. The healing rays of natural sunlight cannot penetrate glass. So you don't generate vitamin D when sitting in your car or home.
  3. People with dark skin pigmentation may need 20 - 30 times as much exposure to sunlight as fair-skinned people to generate the same amount of vitamin D.
  4. Even weak sunscreens (SPF=8) block our body's ability to generate vitamin D by 95%.

It is often difficult to know where to find the minerals and vitamins recommended for an ideal bone-building program. The nutrients listed below have been taken from the United States Department of Agriculture (USDA) National Nutrient Database for Standard Reference. This database is used in food policy, research and nutrition monitoring in the US.

Vitamin K

Vitamin K helps to put calcium where it belongs (in the bones and teeth) and keep it away from the places it doesn't belong, such as the arteries. It is recommended that we get 120 to 150 micrograms of K1 a day although there is also research suggesting that 200 micrograms is necessary for optimal bone health and to prevent osteoporosis.

The FDAA guides us to some of the most popular sources of Vitamin K1. One cup of leafy greens can provide more than our daily requirements.

  • Kale: 1062 mg
  • Spinach: 888 mg
  • Collards: 836 mg
  • Beet Greens: 697 mg
  • Broccoli: 220 mg
  • Brussel Sprouts: 218 mg

Vitamin K2 can be made in our bodies from the vitamin K1 found in green vegetables-but ideally our diet will also contain ample sources of K2 itself. Animals who eat grass use K1 to make K2 and thus they are the best dietary source. Get your K2 from butter, milk with fat, cheese (gouda and edam), organ meats and fat of animals raised on grass.

If you are taking blood thinning medication or an anticoagulant (such as Warfarin, Coumadin or Heparin) be sure to consult your doctor before increasing vitamin K in your diet or supplements.


To prevent osteoporosis, we are interested both in our bone density and our bone quality. Getting enough magnesium is vitally important to ensure that we are building high quality bone mass that is not brittle and subject to fractures.

Most people will not get enough magnesium in their diets if they eat large amounts of processed foods in which much of the magnesium is removed.

Since magnesium works closely with calcium, it is important to have an appropriate ratio of both minerals in order for them to be effective. The recommended amount of magnesium is 300 mg to 500 mg daily.

As with calcium, chelated forms of magnesium are absorbed best by the body and should be taken with food. (A good rule of thumb is a 2:1 calcium-to-magnesium ratio.)

Magnesium oxide is also available and is often less expensive, but it is poorly absorbed by the body. Since high doses of magnesium can cause diarrhea, you should divide your doses and take them with meals throughout the day.

Selected food sources of magnesium include the following:


  • Halibut (1/2 fillet, 159 g) 170 mg
  • Haddock (1 fillet, 150g) 75 mg
  • Flounder and Sole (1 fillet, 127 g) 75 mg

Beans And Legumes (1 Cup, Canned)

  • White Beans: 134 mg
  • Lima Beans: 101 mg
  • Refried beans: 96 mg
  • Lima beans: 94 mg
  • Beans (pork and sweet sauce): 84 mg
  • Kidney beans: 80 mg
  • Lentils: 71 mg
  • Chickpeas: 70 mg

Nuts (1 Oz, Roasted)

  • Brazil Nuts (6-8 nuts) 107 mg.
  • Cashews (18 nuts) 77 mg.
  • Almonds (18 nuts) 76 mg.

Vegetables (1 Cup Cooked)

  • Spinach 157 mg.
  • Beet Greens 98 mg.

Cereal (1 Cup)

  • All-Bran Cereal (Kellogg): 218 mg.
  • Wheat flour: 166 mg.
  • Cornmeal, whole grain yellow: 155 mg.
  • Oat bran (cooked): 88 mg.
  • Raison Bran (Kellogg): 77 mg.


Research suggests that boron mimics the action of estrogen and testosterone needed for bone health.

Fortunately, nuts are an excellent source of both magnesium and boron and dried fruits are a great source of boron. Some of the highest concentrations are found in the following foods.


  • Almonds
  • Hazel Nuts
  • Peanut Butter
  • Brazil Nuts
  • Walnuts
  • Cashews

Dried Fruit

  • Raisons
  • Apricots
  • Dates