If you like to stay up-to-date on the world of supplements, you may be familiarised with the debate that surrounds supplementing vitamin D3. Even though this nutrient greatly benefits and contributes to healthy bones and tissue, critics warn that the continued ingestion of vitamin D3 may in fact weaken blood vessels in the short and long term.
However, there’s good news - a vitamin that has been hiding in the shadows: K2 or menaquinone, has actually been shown to enhance the beneficial effects of vitamin D3 while also preventing any potentially harmful side effects from its continued consumption. Think it's too good to be true? Read on to learn more about the power of these vitamins combined!
- 1 Weekly newsletter with the best personal finance tips
- 2 Key Facts
- 3 The best vitamin D3 and K2 supplements
- 4 Shopping Guide: Everything you should know about the effects of vitamin D3 and K2 when combined
- 4.1 What is vitamin D3 exactly?
- 4.2 Why is vitamin D3 considered superior to vitamin D2?
- 4.3 What is the function of vitamin D3?
- 4.4 What is vitamin K2 exactly?
- 4.5 What is the difference between vitamin K2 and vitamin K1?
- 4.6 What are the functions of vitamin K2 in the body?
- 4.7 How do vitamin D3 and vitamin K2 relate with eachother?
- 4.8 What are the recommended doses of vitamin D3 and vitamin K2?
- 4.9 Who is likely to be affected by vitamin D3 and K2 deficiencies?
- 4.10 What sort of health problems can be caused by an imbalance of vitamin D3 and K2?
- 4.11 How can I increase my levels of vitamins D3 and K2?
- 4.12 What foods are rich in vitamin D3?
- 4.13 What foods are rich in vitamin K2?
- 4.14 Who should incorporate a vitamin D3 and K2 supplement into their diet?
- 4.15 What kind of vitamin D3 and K2 supplements are there?
- 4.16 How do I take my vitamin D3 and K2 supplement?
- 4.17 What benefits can I expect from taking a vitamin D3 and K2 supplement?
- 4.18 Is it possible to take too much vitamin D3 and K2 through supplements?
- 4.19 What adverse effects can a vitamin D3 and K2 supplement have on the body?
- 4.20 When is it not recommended to take a vitamin D3 and K2 supplement?
- 5 Shopping Criteria
- 6 Summary
- Vitamin D3, or cholecalciferol, is a form of vitamin D that is present in certain animal products. This variation of the vitamin is also synthesised in the body from exposure to sunlight.
- In the past, some studies have linked the overconsumption of vitamin D supplements with an excessive amount of calcium deposits in blood vessels, which may be harmful to our overall health.
- Until recently vitamin K2, was only known for being an integral player in blood coagulation and preventing arterial calcification. Today, vitamin K2 is also being acknowledged for its capacity to increase the safety of taking vitamin D3 for a prolonged period of time.
The best vitamin D3 and K2 supplements
It is understandable that the rise in popularity of vitamin D3 and K2 supplements might make it more difficult to know which product is best for you. In this guide, we’ve selected the best vitamin D3 and K2 supplements of 2019. The ranking below contains the five best supplements available to you, we have ranked them in terms of effectiveness, safety and best value for money.
Shopping Guide: Everything you should know about the effects of vitamin D3 and K2 when combined
Vitamin D is essential for the maintenance of bone, heart and brain health. Its most potent form, vitamin D3, stimulates the absorption of calcium from the diet. At the same time, vitamin K2 ensures that the absorbed calcium is deposited in the right place (bones and teeth).
What is vitamin D3 exactly?
Vitamin D is a fat-soluble molecule (dissolved in fats). Although there are up to five different variations of this vitamin, the human body is only able to recognise and utilise two of them: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). The latter is more powerful compared to ergocalciferol.
Vitamin D2 can be found in plant based foods and some fungi, while the intake of animal products will most effectively increase vitamin D3 reserves. Sun exposure, surprisingly, also promotes the production of cholecalciferol, which is why vitamin D3 is also known as the "sunshine vitamin”.
Why is vitamin D3 considered superior to vitamin D2?
- Vitamin D2 or ergocalciferol is mainly found in some plant foods. Certain fungi are capable of producing it after exposure to ultraviolet radiation from the sun.
- Vitamin D3 or cholecalciferol is abundant in numerous animal products such as oily fish, eggs and dairy products. It is also synthesised in the skin after exposure to solar UVB radiation.
However, numerous studies have shown that vitamin D3 produces has a higher conversion to calcitriol (the bio available form) compared to its analogue, vitamin D2. Vitamin D3 comprises 60% of what our bodies need in order to keep vitamin D labels stable.
Unfortunately, vitamin D3 supplements will have some kind of animal ingredient in most cases (usually fish oil). This makes it very important for vegans and vegetarians to be exposed to the sun half an hour a day if they want to increase their vitamin D3 reserves naturally.
What is the function of vitamin D3?
- Increased intestinal absorption of calcium
- Regulation of levels of phosphorus and calcium in the kidneys
- Creation of new bone
- Teeth strengthening
- Replacing of damaged bone tissue
- Capability of muscle contraction
- Reduction in blood pressure
- Regulation of inflammations
- Strengthening of the immune system
- Protection of neuronal tissue against ageing
- Mood regulation
- Regulation of hormone production (oestrogen and testosterone)
- Appetite regulation
We should note that 99% of the vitamin D stored in the body will be used to regulate the levels of calcium in tissues. The remaining 1% will act as an essential cofactor for the proper functioning of different processes essential for the well-being of the body, such as weight regulation or the development of strong muscles.
What is vitamin K2 exactly?
Currently, there are five variants of this vitamin. Its two natural derivatives are vitamin K1 or phylloquinone (abundant in green, leafy vegetables) and vitamin K2 or menaquinone (present in animal products and fermented products such as cheese or nattō, a soybean derivative).
What is the difference between vitamin K2 and vitamin K1?
Although both vitamins are essential components for the activation of the proteins that regulate blood coagulation and other equally important metabolic processes of the body, vitamin K2 is associated with a decrease in calcium deposits in blood vessels, which leads to improving vascular health. This is an important distinction because vitamin K1 lacks this property.
Several studies have found that older individuals (especially women) who maintain elevated vitamin K2 levels benefit from lower incidences of osteoporosis and arterial calcification, something that does not occur among K1 users. This is the main difference between the two molecules.
What are the functions of vitamin K2 in the body?
Moreover, vitamin K2 possesses a number of properties which appear to be unique qualities. Below we’ve provided a comparative table that includes the functions of all the forms of vitamin K on one side, and those particular characteristics of menaquinone on the other.
|Functions of vitamin K||Functions unique to vitamin K2|
|Activation of coagulation||Bone mineralization|
|Bone formation||Prevention of arterial calcification|
|Protection of neurones||Prevention of cardiac calcification|
|Cellular antioxidant||Tooth enamel reinforcement|
|Immune response enhancer||Cutaneous cellular antioxidant|
|Regulation of metabolism||Regulation of hormone production (increase of testosterone in men and decrease in women)|
Vitamin K2 has been a nutrient that has not been studied much until relatively recently. More evidence is needed before all of its beneficial effects can be officially confirmed. Even so, the most recent studies provide very promising data that reinforces the notion that vitamin K2 is an indispensable nutrient for good health.
How do vitamin D3 and vitamin K2 relate with eachother?
Vitamin K2 will then contribute to bone mineralization while at the same time, activating a series of proteins closely related to maintaining the calcium present in bone and tooth tissue and enamel. This process will increase the amount of mineral (calcium) deposited in the bones and decrease the concentration of calcium in other places, making it capable of impairing the functioning of other organs.
For this reason many nutrition experts consider these vitamins to be synergistic, that is, capable of working together to enhance their beneficial actions. Vitamin K2 allows vitamin D3 to exert its effects while preventing the adverse effects associated with its ongoing supplementation or ingestion.
What are the recommended doses of vitamin D3 and vitamin K2?
In the case of vitamin D3, RDA can be quantified in the form of International Units (IU), a parameter that measures the degree of biological activity, in nano-grams (ng) or in micrograms (μg). The RDA for vitamin K2 on the other hand, shall be measured in micrograms. In the following table you can consult the RDA for each of these substances:
|Population group||CDR vitamin D3||CDR vitamin K2 (ug)|
|Babies 0-6 months||400 IU or 10 μg||2 μg|
|Babies 6-12 months||400 IU or 10 μg||2.5 μg|
|Children 1-3 years||600 IU or 15 μg||30 μg|
|Children 4-8 years||600 IU or 15 μg||55 μg|
|Adolescents 9-18 years||600 IU or 15 μg||60 μg|
|Adults up to 70 years||600 IU or 15 μg||75 μg|
|Women over 70 years||800 IU or 20 μg||90 μg|
|Men over 70 years||800 IU or 20 μg||120 μg|
Who is likely to be affected by vitamin D3 and K2 deficiencies?
Vitamin D3 deficiency is also very common in western societies. It is estimated that 30-80% of the world's population suffers from some form of vitamin deficiency, caused mainly by reduced exposure to sunlight, the abuse of sunscreens and the promotion of a sedentary lifestyle.
Keep in mind that certain individuals will be much more vulnerable to entering a state of hypovitaminosis with respect to vitamin D3 or K2 than the general population. The people listed below should carefully plan their diet if they want to avoid any imbalance related to low absorption or excessive accumulation of these vitamins:
- Those over 60 years old: The capacity to absorb, store and synthesise these vitamins decreases with age. Meaning they may not be able to utilise the stored nutrients putting them at risk of excessive calcium deposits in blood vessels.
- People with night shifts, office workers and students: Their sun exposure is less than the amount that is recommended to maintain vitamin D3 levels within healthy limits.
- People with naturally very dark skin: The pigment (melanin) in dark skin doesn't absorb as much UV radiation. Which reduces the skin’s ability to make synthesise vitamin D in response to sunlight exposure.
- Vegans and vegetarians: Cholecalciferol and menaquinone are difficult to find in a plant-based diet, which increases the likelihood of this population group experiencing deficiencies in either of these nutrients.
- People who frequently use sunscreen: By blocking ultraviolet radiation, vitamin D3 formation will also be impaired.
- People with chronic intestinal diseases: Absorption of all vitamins (including D3 and K2) will be affected in cases of malabsorption disorders (such as ulcerative colitis or Crohn's disease).
- People who often take antibiotics : Antibiotics work to eradicate all bacteria in the body, including beneficial intestinal bacteria, which contributes to the absorption of vitamin K2. Therefore, its destruction will affect the levels of this vitamin in the body.
- People who drink too much alcohol: This oxidising substance works against the absorption of vitamin K2 while also hindering its functions.
What sort of health problems can be caused by an imbalance of vitamin D3 and K2?
Problems caused by vitamin K2 deficiencies will have a greater effect on the body's ability to form blood clots. Which means minimal amounts of rubbing, bruising, or minor wounds (e.g. bleeding in the gums after tooth brushing) will begin to bleed excessively. This could happen internally or externally. In the case of women, these complications can become quite severe and will often take time to disappear once vitamin levels are returned back to normal.
It is important to note however, that if vitamin D3 levels remain high but vitamin K2 levels fall, there is a great likelihood that calcium deposits in the arteries (absorbed from the diet or supplements) will drastically increase. This in turn can cause hypertension, which will slowly and discreetly damage the heart and kidneys.
How can I increase my levels of vitamins D3 and K2?
Vitamin K2 is much more difficult to obtain through foods, especially if you follow a "western" diet (such as the Mediterranean diet). This nutrient is present in green leafy vegetables, such as kale, spinach, collards, and many more. Vegetables such as Brussels sprouts, broccoli, cauliflower, and cabbage. It is also present in lesser amounts in animal products such as goose liver or free-range eggs. It is much more abundant in fermented foods such as nattō and some cheeses.
What foods are rich in vitamin D3?
|Food||Approximate Concentration (UI)||% RDA (for an adult)|
|Cod liver oil (1 tablespoon)||500||80|
|Salmon (75 g)||350||60|
|Mackerel (75 g)||200||30|
|Tuna (75 g)||150||25|
|Sardines ( 75g)||150||25|
|Fortified milk (250 ml)||100||15|
|Egg yolk (unit)||45||8|
|Veal liver (75 g)||35||6|
|Fortified margarine (1 tablespoon)||30||5|
Although the absorption of vitamin D3 through diet is less efficient than the production of this substance through sun exposure, a varied diet rich in these foods can provide a sufficient amount of cholecalciferol to produce optimal bone, mental and heart health.
What foods are rich in vitamin K2?
Fermented foods - rich in menaquinone - should be refrigerated and stored properly to prevent the vitamin K2 present in them from deteriorating. The table below lists foods rich in vitamin K2, both of animal origin and fermented:
|Food||Approximate Concentration (ɥg)||% CDR(for an adult)|
|Goose pâté (100g)||369||500|
|Hard cheeses: Parmesan, Emmental and Gruyere (100g)||75||100|
|Brie cheeses (100g)||50||65|
|free-range egg yolk||32||45|
|Caged chicken egg yolk||15||20|
|Chicken breast (100g)||9||12|
|Veal liver (100g)||5||7|
|Whole milk (100 ml)||1||1|
Who should incorporate a vitamin D3 and K2 supplement into their diet?
- Those over 60 years old
- Strict vegans or vegetarians
- Individuals with limited exposure to sunlight
- Postmenopausal women, especially if they suffer from loss of bone density
- Obese individuals
- People who have undergone bariatric surgery or some type of intestinal resection
- People with cardiovascular problems (hypertension, heart failure)
- People who follow very restrictive or unbalanced diets
- People with renal insufficiency
The combination of vitamin D3 and K2 will especially benefit those with a family or personal history of cardiac events associated with arterial calcification and obstruction. In these cases, vitamin K2 will act as a shielding agent to mitigate the effects of ongoing vitamin D supplementation, basically regulating calcium deposits in the arteries.
What kind of vitamin D3 and K2 supplements are there?
In the case of vitamin K2, there are several isoforms (molecular variants) available for its use as a food supplement. The most commonly used vitamin K2 supplements are those known as "vitamin K2 MK-4" and "vitamin K2 MK-7". Their effects and processes within the body are summarised below:
- Vitamin K2 MK-4: MK-4 is the most active form of vitamin K2. This substance is rapidly absorbed and stored in the brain, arteries, pancreas and salivary glands.
- Vitamin K2 MK-7: This form of vitamin K2 absorbs more easily into bone and liver tissues, where vitamin K2 MK-4 is then metabolised so it can carry out its beneficial effects within a multitude of processes in the body.
Experts advise using a vitamin D3 and K2 supplement containing a balanced combination of both menaquinone isoforms. This way, vitamin K2 can reach all parts of the body equally, protecting bones, arteries, kidneys and brain tissue equally.
How do I take my vitamin D3 and K2 supplement?
- Which supplement should I choose? It is advisable to choose a supplement that provides the recommended daily amount of vitamin D3 and K2 for your needs in one dose. Generally, items on sale offer much higher amounts than the RDA of cholecalciferol and menaquinone, so a single daily dose of the supplement will suffice in most cases.
- In what proportion should these vitamins come? Remember that an adequate amount of vitamin K2 will ensure the correct use of vitamin D3 and prevent the arterial calcification caused by excessive calcium deposits. Most experts recommend that the chosen supplement contains at least 45 ɥg of vitamin K2 per 1,000 IU of cholecalciferol.
- When should these supplements be consumed? As vitamin D3 and vitamin K2 are fat-soluble molecules, their absorption is enhanced if they are taken with meals, accompanied preferably by fatty or seasoned foods. A salad dressed with olive oil, for example, will favour the assimilation of both vitamins into the body.
What benefits can I expect from taking a vitamin D3 and K2 supplement?
- Increased muscle performance (increased capacity for contraction, strength and endurance)
- Drop in blood pressure
- Increased bone density with decreased incidence of fractures
- Decreased incidence of heart or coronary disease
- Improved state of blood vessels, decreased occurrence of varicose veins
- Strengthening of tooth enamel and a lowered incidence of cavities
- Increased energy
- Protection against infections (colds and flues)
- Improved mood
- Preservation of intellectual capacities (especially memory)
- Decrease in LDL cholesterol ("bad" cholesterol)
- Improvement in blood coagulation
- Overall improvement of the skin tissue
- Alleviation of symptoms from psoriasis and other chronic inflammatory diseases
- Quicker recovery from haematomas ("bruises")
- Regulation of testosterone production in men
- Improvement of symptoms of Polycystic Ovary Syndrome in women
- Decreased sensitivity to insulin, with reduced blood glucose levels
Furthermore, some studies have also come to establish a relationship between optimal levels of these vitamins and a lower incidence of cancer. Different studies have been published (on breast cancer, colon cancer and prostate cancer, among others) that offer promising results on the tumour-reducing capacity of these substances.
Is it possible to take too much vitamin D3 and K2 through supplements?
Moreover, vitamin K2 is also a fat-soluble substance. Paradoxically, no toxic side-effects have been described in the consumption of this molecule, even at very high doses (100 or more times the RDA). For this reason, there has been no consensus on a maximum daily intake limit for menaquinone.
Therefore, it’s advisable not to exceed a daily limit of 4,000 IU for vitamin D3. In addition, it is important to choose a supplement containing 45 ɥg of menaquinone per 1,000 IU of cholecalciferol, in order to avoid any negative side effects. It is important to remember that although there is no established limit for vitamin K2, the RDA should not be exceeded.
What adverse effects can a vitamin D3 and K2 supplement have on the body?
- Frequent adverse effects: Some uncomfortable, but minor, side effects may occur, such as flatulence, abdominal discomfort, and a feeling of abdominal bloating. This discomfort will gradually disappear once the body becomes accustomed to the digestion of the newly incorporated supplement.
- More severe and less frequent side effects: Some people have experienced very unpleasant side effects during vitamin D3 and K2 supplementation including nausea, vomiting, and severe abdominal pain. These effects are much less frequent than those described in the previous paragraph, but will require for an immediate adjustment of the dose or even ceasing supplementation altogether. If you experience any of these symptoms, be sure to consult your family doctor at your earliest convenience.
- Very rare adverse effects: Very rarely, even more severe side effects may occur, such as intense vomiting and diarrhoea, loss of appetite and muscle weakness. In this case, it is recommended that you stop taking the supplement immediately and go to a medical centre as soon as possible.
When is it not recommended to take a vitamin D3 and K2 supplement?
Moreover, individuals who suffer form liver or kidney problems have a delicate metabolism and should consult their family doctor before taking any kind of vitamin D or K supplement. As a general rule, unsupervised vitamin intake is not recommended for pregnant or breastfeeding women.
Finally, it’s necessary to take into account the possibility of any drug interactions between these vitamins and other forms of medical treatment. If you are a regular user of any of the drugs listed below, consult your doctor before starting supplementation:
- Warfarin (vitamin K antagonist anticoagulant)
- Treatment for chronic renal failure
- Hipolipemiantes (cholesterol-lowering drugs) such as Orlistat
- Medicine for the treatment of psoriasis
- Some antibiotics, such as tetracyclines
- Digoxin (anti-arrhythmic treatment)
- Treatment for hypertension
- Thyroid hormones
- Some diuretics
In this next section we include some purchase criteria to keep in mind, which we hope will help you choose the vitamin D3 and K2 supplement that best suits your needs. The following list contains all of the most outstanding features these products can have. Make sure not to overlook any of them if you want to ensure the purchase of a top quality item.
- Vegan or vegetarian restrictions
- Added minerals
- Method of ingestion
- Best value for your money
Very rarely, allergic reactions may occur after to the use of vitamin D3 and K2 supplements. Hypersensitivity symptoms will usually be due to intolerance of one of the excipients within the product, not the actual vitamin itself. Check the ingredients of your chosen product very carefully if you are intolerant of any other food compound such as gluten or lactose.
Vegan or vegetarian restrictions
It’s important to remember that plant-based vitamin D3 and vegan K2 supplements are difficult to find. Cholecalciferol is a compound found almost exclusively in foods of animal origin, which is why many vegans and vegetarians prefer to use vitamin D2 supplements, which are easily obtained from plant sources.
Nonetheless, some vitamin D3 and K2 supplements suitable for vegans have begun to emerge. In these products, according to the manufacturers, the cholecalciferol has been obtained from specially cultivated fungi or lichens. This may be a good option for vegans who want to continue supplementation.
Some vitamin D3 and K2 supplements may contain added minerals such as calcium, phosphorus, or magnesium. If you’re given this choice, most experts recommend choosing a supplement that contains magnesium. An increased vitamin D3 intake will help increase the absorption of phosphorus and calcium, making their supplementation unnecessary.
You may want to take a closer look at the dose of vitamin D3 in your menaquinone-cholecalciferol supplement. The dose of D3 should never exceed 4,000 UI. It is much safer to use amounts close to CDR (800-1,000 UI).
Method of ingestion
In the case of vitamin D3 and K2 supplements, the method of ingestion will not usually influence the absorption or overall effectiveness of the product. For this reason, we recommend that you choose the the format that fits your needs and preferences. You can find these supplements in many forms and presentations:
- Tablets: These are surrounded by special coating that gives them a pleasant taste and facilitates their ingestion.
- Soft-gels: This type of supplement is especially suitable for those individuals who find it difficult to swallow large pills.
- Oral spray: This ingenious form allows you to forget any aversion you may have towards taking pills. Fun fact: Some products are suitable for spraying on food or even served as a dressing.
- Drops: This form of supplement contains an easy to administer dropper that allows to adjust the supplement dosage precisely.
- Powder: This type of supplement can be easily mixed into purees, drinks or shakes, providing large amounts of nutrition in a delicious drinkable form. It also allows you to adjust the doses more accurately.
Best value for your money
The effects of vitamin D3 and K2 supplements begin to manifest within just a few weeks of starting treatment. However, these items need to be used for six or more months to resolve any complications you’re experience due to hypovitaminosis. If you anticipate the need for prolonged supplementation, we suggest you invest in "extra large" packaging, which will save you money in the long run.
The combination of vitamin D3 and K2 has increased substantially in the world of supplementation. These two molecules form an unparalleled team that allows you to reap all the benefits of cholecalciferol, while limiting its negative side effects. Moreover, their combined antioxidant qualities have made this supplement an indispensable health product.
If you follow our advice, you’ll be able to get the most out of your vitamin D3 and K2 supplement. Remember that the intelligent use of this product will help protect your bones and support the health of your cardiovascular system at the same time, allowing you to enjoy an active, disease-free life for many years to come. Don't lose sight of this wonderful supplement!
If you liked our guide to vitamin D3 and K2, please leave a comment with your thoughts and share this article.
(Featured image source: McAdam: 76443287/ 123rf.com)