Marc Joseph Nutrition - Blog

In a review study published in the journal Thrombosis and Hemostasis, researchers note that vitamin K deficiency may be much more common than previously thought.

A primary action of vitamin K in the body is to help in a chemical reaction called carboxylation. Potential vitamin K deficiencies can be identified by measuring in the body the level of under-carboxylated compounds, such as osteocalcin and matrix Gla protein (MGP), both of which are involved in the maintenance of bone structure.

The scientists note that there is a substantial amount of incompletely metabolized osteocalcin and MGP in many otherwise apparently healthy individuals, which suggests that the majority of these people may be subclinically deficient in vitamin K.

Results Not Surprising

The findings aren’t too surprising, given that the primary dietary sources of vitamin K are:

• Green, leafy vegetables - spinach, kale, chard, lettuce
• Broccoli
• Parsley

These aren’t foods that most people eat regularly in adequate amounts (e.g., a cup per day). And, the biological half-life of vitamin K is relatively short — a few days. That means if you’re not regularly consuming vitamin K, you may become deficient.

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In a study published in the American Journal of Clinical Nutrition, researchers have found that many Americans, especially men, ethnic minorities, and individuals with less education, are not getting adequate intake of calcium.

Specifically, only 40% of the US men and women included in the 1999–2002 National Health and Nutrition Examination Survey met the Adequate Intake (AI)* for calcium. And that’s with nearly half (48%) of the survey participants taking calcium supplements.

* The government doesn’t set a Recommended Daily Allowance (RDA) for calcium. Instead, an AI level (representing the daily suggested total intake from both diet and supplements) is set because of the lack of definitive knowledge regarding how nutrition, genetics, hormone balance, physical activity, etc. interact to affect bone health. The AI for adults ages 19 to 50 is 1000 mg, and for adults over age 50 it is 1200 mg.

Several groups in the study were more likely to have adequate calcium intake :

• Women - 60% more likely than men
• Caucasians - 90% more likely than non-Caucasians
• Education beyond high school - 50% more likely than those with less than high school education
• Individuals diagnosed with osteoporosis - 90% more likely than people over age 50 without the condition

Not Just Calcium

There are many factors other than calcium intake that can also affect your risk for developing osteoporosis, including:

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Adding to a growing body of evidence that links Omega-3 fatty acid intake with healthy bone growth, a study just out in the American Journal of Clinical Nutrition (AJCN) found that healthy teenage boys with higher serum levels of Omega-3 fatty acids, especially DHA (docosahexanoic acid), had significantly greater bone mineral density accrual between the ages of 16 and 22.

This result is important, as bone growth during the teenage years is key to building a high peak bone mass that may reduce the risk of developing osteoporosis later in life.

In a related earlier study published in the AJCN, researchers found that among older adults age 45 to 90, a higher ratio of Omega-6 to Omega-3 fatty acid intake was associated with a significantly lower bone mass density at the hip.

Omega-3 fats EPA and DHA are found primarily in fish oil, while the main sources for Omega-6 fats in the diet are vegetable oils (corn, soybean, sunflower, safflower). Most people eat far too much Omega-6 fats relative to Omega-3 fats. The estimated ratio in Western diets is 15:1, whereas a ratio between 1:1 to 4:1 is believed to be optimal.

How Fat Intake Affects Bone Growth

The exact mechanism for how higher levels of Omega-3 fats and/or a lower Omega-6/Omega-3 fat intake ratio may assist bone growth is not yet entirely understood. However, an accompanying editorial to this month’s study in the AJCN, makes some interesting observations:

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Leading scientists affiliated with the Council for Responsible Nutrition, Mount Sinai Hospital (Toronto), and Creighton University published a review article in the most recent issue of the American Journal of Clinical Nutrition calling for a five-fold increase in the recommended tolerable upper intake level (UL) of vitamin D.

(UL = the maximum level of daily nutrient intake that is likely to pose no risk of adverse effects)

The current vitamin D UL is 2000 IU (50 micrograms/day). The article’s authors review the existing research and make the case that the UL should be raised to 10,000 IU (250 mcg/day).

The UL established by the FNB [Food & Nutrition Board] for vitamin D (50 mcg, or 2000 IU) is not based on current evidence and is viewed by many as being too restrictive, thus curtailing research, commercial development, and optimization of nutritional policy. Human clinical trial data published subsequent to the establishment of the FNB vitamin D UL published in 1997 support a significantly higher UL.

The authors note that the initial UL was set based primarily on research associated with the function of vitamin D in bone formation, but that more recent research has shown vitamin D to play important roles in other areas (e.g., immunity), and that potentially higher necessary levels may be necessary for optimal function. The authors cite several clinical trials using as much as 1250 mcg/day of vitamin D with no observed negative side effects.

The primary source of vitamin D is sunshine, with the average diet providing less than 10 mcg (or 400 IU/day) — and that’s only in people regularly consuming significant amounts of vitamin D fortified foods, such as some dairy products.

As discussed frequently in this blog, vitamin D deficiency is widespread, with some estimates suggesting as much as 60 percent of people in Northern latitudes aren’t getting enough. Deficiency rates are also high among certain groups at all latitudes, such as among the elderly and people who work inside all day.

See this recent post for more vitamin D discussion and embedded links to several other posts relevant to the topic:

Higher Vitamin D Levels May Help Protect Against Multiple Sclerosis

Hopefully the Food and Nutrition Board, which is responsible for setting recommended intake and ULs, will seriously consider this call for an increase in vitamin D levels.

A couple of weeks ago, I talked about the importance of adequate vitamin K intake in helping to prevent the calcification (hardening) of blood vessels often seen in heart disease and cerebrovascular diseases, such as stroke and Alzheimer’s Disease.

Just as vitamin K is critical for preventing the calcification of blood vessels, it is also essential for calcifying bones and keeping them healthy and strong.

In a recent study, researchers with the University of Michigan School of Nursing found that the current government recommended intake of vitamin K may not be high enough for peri-menopausal women in order to avoid a decline in bone mass density (BMD).

The protein osteocalcin, which helps to bind calcium to bone, requires vitamin K in order to work properly. Researchers found a higher percentage of inactive (or undercarboxylated) osteocalcin in early post-menopausal women 40-52 years old, indicating that they may have inadequate vitamin K levels in order to prevent bone loss.

The researchers also noted that a decline in estrogen levels may impair vitamin K function in bones even before bone loss can be measured.

Given that:

• Vitamin K is found in significant amounts in only a few foods (e.g., leafy greens)
• These foods are not eaten regularly and in large amounts by most people
• And the results of this study and others like it indicate the importance of vitamin K for maintaining healthy bones

It makes sense if you are a peri-menopausal woman to regularly supplement with this nutrient, preferably with a supplement that contains both primary forms of the vitamin — K1 and K2.

Two Important Notes:

Vitamin K is fat-soluble. It needs to be eaten with a meal containing fat for proper absorption.

Vitamin K also affects blood clotting. People taking blood thinning drugs need to talk with their physicians before supplementing, as increasing vitamin K intake may change the necessary prescription.

A large recent study looked at how vitamin K intake might affect cardiovascular disease and stroke in men. The study found that risk of cardiovascular disease and stroke fell by as much as 18 percent in individuals consuming higher levels of vitamin K.

The results did not remain significant after adjusting for lifestyle and other dietary factors. In other words, it wasn’t clear whether the risk declined because of the vitamin K intake or just as a result of healthier living.

Yet, there are good scientific reasons to believe that vitamin K is important in helping to maintain vascular health. Specifically, vitamin K helps the body to keep calcium in the bones and teeth, where most of it belongs, thus helping to reduce the calcification of soft tissues, such as blood vessels. The exact mechanism is not known, but it is thought to be related to a protein (MGP - Matrix Gla Protein), which inhibits calcification and is vitamin K dependent.

A 2004 study found that higher vitamin K2* dietary intake was associated with reduced cardiovascular mortality, overall mortality, and aortic calcification.

* There are three different forms of vitamin K:

• K1 (phylloquinone) - found primarily in plants (esp. leafy greens)
• K2 (menaquinone) - found in animal products and synthesized in the GI tract (produced by micro-organisms)
• K3 - synthetic

Vitamin K1 is the predominant form of the vitamin in the diet and is primarily found in green vegetables, including spinach, broccoli, chard, kale, parsley, etc.

Deficiency is common:

• Many people don’t eat foods high in vitamin K regularly or in adequate quantities, and thus don’t get enough of the vitamin.
• With age, the GI tract tends to become less efficient at producing the K2 form of the vitamin.
• Antibiotic use can interfere with the production of vitamin K2 in the GI tract.

Bottom line:

Supplementation with vitamin K containing the K1 and K2 forms can help to fill the gap and may help to reduce the risk for blood vessel calcification associated with heart disease and stroke.

Two important notes:

Vitamin K is fat-soluble. It needs to be eaten with a meal containing fat for proper absorption.

Vitamin K also affects blood clotting. People taking blood thinning drugs need to talk with their physician before supplementing, as increasing vitamin K intake may change the necessary prescription.

In this American Journal of Clinical Nutrition editorial, the authors discuss the important issue of vitamin D deficiency during pregnancy.

The authors mention a recent study of women in the Netherlands, and note that the study found that >50% (!) of darker-skinned women were deficient in vitamin D (whereas only 8% of fairer-skinned women were).

But the numbers were likely even worse than those. The study used a very conservative level of vitamin D to indicate vitamin D deficiency, one that was likely much too low.

The correct vitamin D form to measure for deficiency is 25-hydroxyvitamin D. The study used 25 nmol/L as the cut-off, while levels closer to 80 nmol/L are increasingly being shown in research to be optimal.

As the editorial notes, Vitamin D levels during pregnancy and the early years of development are critical not only for bone development, but also for the immune system and nervous system development — and may have lifelong implications.

It is difficult to get adequate vitamin D through the diet, since dairy is really the only food category that contains significant amounts of the nutrient.

The primary source of vitamin D is from sunshine. The sun’s UV-B rays hit the skin and a molecule is converted that starts a multi-step process toward the formation of active vitamin D in the body. Exposure to mid-day summer sun at the beach can generate up to 20,000 IU of active vitamin D.

In Northern latitudes during the winter months, the sun’s rays are not strong enough to generate sufficient vitamin D levels. Also, individuals with darker skin require significantly greater levels of sun exposure to generate adequate amounts of vitamin D.

Unfortunately, the U.S. government’s current recommended adequate intake level for vitamin D (200 to 600 IU) is set way below the level necessary to maintain vitamin D near optimal levels. As discussed here, adequate daily intake levels may be at least 2,000 IU/day, and possibly higher, for individuals not getting regular, limited sun exposure*.

During the winter months and in groups of people with limited sun exposure (e.g., infants, the elderly, darker-skinned people spending lots of time indoors), supplementation with vitamin D, either in the form of cholecalciferol or obtained via a good quality (toxin-free) cod liver oil will likely be important in helping to maintain adequate vitamin D levels.

(Vitamin D is a critically important nutrient that is commonly deficient. I’ll regularly revisit this topic in future posts.)

* Note: Neither vitamin D researchers or I are suggesting that you should spend a lot of time in the sun. Excessive exposure to the sun’s rays can damage the skin. The amount of exposure required for adequate vitamin D formation is brief — 10 to 15 minutes a day on the exposed arms/neck/face a few times a week during spring, summer, and early fall.