IF YOU LIVE North of San Francisco, California or Richmond, Virginia you should be taking at least 1000 IU of vitamin D per day within the months of October until March.
If you notice you get SAD (seasonal affective disorder) in the winter months, likely you need a lot more.
The best way to know if you need to start taking vitamin D and how much is to get tested. Optimal levels of plasma (or serum) 25(OH)D concentration is above 75nmol/L.
Getting the down low on vitamin D
Vitamin D insufficiency is a global problem. Let’s see how vitamin D is not only helpful for your mood, but also bone health, blood sugar and immune support:
Seasonal Affective Disorder (SAD)
Seasonal affective disorder (SAD) is defined as a bipolar or recurrent major depressive disorder. SAD was at first believed to be related to abnormal melatonin metabolism, but now we know this to be untrue.
Criteria for a diagnosis of SAD include:
- Previous depressive episode
- Fall–winter depression alternating with non-depressed periods during spring–summer
- No other variables accounting for mood changes
Typical depressive characteristics are experienced along with increased sleep and appetite. What’s most interesting is that SAD symptoms tend to remit with exposure to daylight or bright light therapy.
Vitamin D promotes calcium and phosphorous absorption, which is necessary to build and maintain bones and teeth. It increases absorption of calcium from foods and reduces the amount of calcium lost in urine.
However, vitamin D can also pull calcium from the bone to balance blood levels. Therefore sufficient levels of dietary or supplemental calcium is required. Adding vitamin K will increase calcium bone absorption while phosphates (ie. soda) will leach calcium out.
Insufficient levels of vitamin D, vitamin K, calcium and other bone forming minerals leads to softening or malformation of bones. In children, this condition is called rickets. In adults, it is called osteomalacia. Inadequate bone health was found at vitamin D concentrations below 37.5 nmol/L, while concentrations above 75 nmol/L reduce fracture risk and improve calcium absorption.
Blood Glucose, Insulin and Diabetes
In 2008, it was estimated that 1 billion individuals presented with vitamin D insufficiency or deficiency. Studies show a positive correlation between circulating vitamin D levels and insulin sensitivity. Low vitamin D levels demonstrate an increased risk of glucose intolerance (high blood sugar), altered insulin secretion and type 2 diabetes.
Studies show a 12-weeks supplement of vitamin D and circuit training has positive effects on abdominal fat and blood lipid levels in vitamin D deficient elderly women with type 2 diabetes. Vitamin D supplementation was especially effective when it was complemented with exercise training.
Your vitamin D status impacts thyroid function. If you have signs of thyroid imbalance but your thyroid tests are normal, this could be due to insufficient vitamin D levels. If you are taking thyroid medication but it is ineffective, have your vitamin D levels checked. This could be a potential reason why the medications are not working.
Circulating vitamin D also functions as a potent anti-estrogenic/anti-progesteronic agent that may be a treatment option for uterine fibroids.
Vitamin D is one of many hormones involved in the white blood cells development. White blood cells are our first line against most types of infection.
Low vitamin D levels have shown an increased risk of respiratory infection and a higher incidence of influenza in the winter months compared to any other times of the year.
A double-blind trial had 208 African-American women received vitamin D3 or placebo for three years. The dosage was 800 IU per day for two years, followed by 2,000 IU per day for one year. During the study, 8 women in the vitamin D group and 26 in the placebo group reported cold and influenza symptoms.
What are the best sources of D?
Sun or light therapy
When UV B light from the sun or artificial light hits skin cells, a molecule in our skin cells called 7-dehydrocholesterol is converted into a preliminary form of vitamin D, cholecalciferol.
Cholecalciferol is transferred into the bloodstream to liver cells to produce 25-hydroxycholecalciferol or 25(OH)D, which is the measurement blood tests look for. Finally, 25(OH)D goes back into the bloodstream to kidney cells, where 25(OH)D is converted into the active form of vitamin D, 1,25-dihydroxycholecalciferol, or 1,25(OH)D.
Salmon, sardines, tuna, cow’s milk, eggs, and shiitake mushrooms have the highest amounts of dietary vitamin D.
Any bony fish, including sardines or canned salmon, would potentially be a rich source of both vitamin D and calcium to encourage strong bone health.
The frequency of milk consumption is significantly related to vitamin D status. Those consuming more than one glass a milk per day have an increase of 12 nmol/L 25(OH)D, compared with those having less.
With so many vegans or people sensitive to dairy it’s important to get your vitamin D from the sun, other food sources or supplementation, especially during the winter months.
Supplemental vitamin D should be in D3 form. Vitamin D is a fat soluble vitamin and is best absorbed when taken with other fats. For example avocado, fish oil, nuts, coconut or olive oil, dairy, or meat.
How do I know how much to take?
The best way to know exactly how much vitamin D to take is to get testing done twice a year (once in winter and once in summer). Comparing your current levels and from season to season will help you determine the appropriate amount of vitamin D supplementation for optimal health.
Plasma (or serum) 25(OH)D concentration is generally considered to be the best form to reflect vitamin D status. It’s the total 25(OH)D from diet, sun conversion and supplementation.
There is a growing consensus that higher concentrations of 25(OH)D, above 75 nmol/L, is desirable for overall health and disease prevention. Concentrations exceeding 375 nmol/L pose a risk of adverse effects and toxicity, but have not been measured during Canadian surveys.
The Recommended Daily Intake (RDI) is a conservative:
- 0-12 months: 400 IU (10 micrograms of cholecalciferol)
- 1-70 years: 600 IU (15 micrograms of cholecalciferol)
- 70+ years: 800 IU (20 micrograms of cholecalciferol)
- Pregnant women: 600 IU (15 micrograms of cholecalciferol)
- Lactating women: 600 IU (15 micrograms of cholecalciferol)
Given the prominence of vitamin D deficiency, these are very conservative recommendations with the goal of avoiding negative vitamin D deficiency symptoms rather than obtaining optimal levels.
If your vitamin D levels are insufficient, increasing your dose to 1000IU per day, especially between October- March, is safe and still a very moderate dose. The tolerable Upper Intake Limit (UL) is 4000 IU per day for vitamin D.
Effects of low vitamin D
Vitamin D deficiencies is a world-wide issue. Lower levels of vitamin D have been associated with a greater risk of:
- Rickets in children
- Osteomalacia in adults
- Loss of balance, increased falls and fractures
- Diabetes and metabolic syndrome
- Rheumatoid arthritis
- Low immune function
- Cardiovascular dysfunction
- Multiple sclerosis
25(OH)D concentrations below 75 nmol/L are also associated with a greater risk of breast cancer, colorectal cancer and adenomas.
Why are we deficient?
According to Health Canada, only 1/3 have healthy levels of vitamin D (above 75 nmol/L). That means over 18 million Canadians have insufficient levels of vitamin D (without one measured participant with toxic measurements of > 375 nmol/L)
The epidemic of vitamin D deficiency is due to several factors:
- Reduced exposure to sunlight
- Winter season in locations North of the 37th parallel
- Strength of the UVB light
- Overall skin health
- Sunscreen use
- Being indoors
- Clothing coverage
- Pregnancy and lactation
- Elevated body mass index (adiposity)
- Darker skin pigmentation
- Age and sex
Get your vitamin D levels checked this winter and start taking at least 1000 IU of D3 per day until March. Eat more fish and when you go outside let your skin be bare and allow at least 10 minutes a day of uninhibited UV-B absorption to boost your mood, bone health, hormonal function and immune system.
What About Skin Cancer?
While over-exposure of UV light (especially UV B) poses a real concern to developing skin cancer, especially in people with a personal or family history of malignant cancer, we should not be afraid of the sun. Use healthy skin prevention and enjoy the outdoors:
- Minimize skin exposure (ie. sunscreen or coverage) between 10am-3pm in the summer months when the sun is strongest.
- Use safe sunscreens or sunblock (non-nano zinc oxide base) if you are going to be out for >30 minute of direct sun exposures.
- Choose an SPF of 15 and reapply often. The SPF rating only extends the time it takes for your skin to “burn” it doesn’t stop it.
- Reapply every time you swim or sweat excessively, even with water-proof or high SPF sunscreens.
- If you use sunscreen, it needs 30 minutes to absorb into your skin so that the chemicals within can alter the UV rays when they penetrate the skin.
- If you use sunblock, you can go out into the sun immediately. Sunblock are mineral-based and provide a protective layer on the skin so that the UV light doesn’t penetrate in.
- Sunblocks often leave white marks once applied because of the zinc oxide.
- All skin colors are affected by UV light, however fair-skinned individuals need to take extra precautions.
- Also practice wearing a hat, long sleeves, sunglasses and staying in the shade if you burn easily.
Be cautious of some sunscreens (purchased and DIY) for they may contain harmful ingredients. Focus on finding a sunscreen or sunblock that includes non-nano zinc oxide and natural oils. Here are some things to avoid when choosing your sunscreen:
- Nano particles are extremely small and can be easily absorbed into the skin causing potential harm.
- Other sun protecting ingredients (such as Oxybenzone) can disrupt hormones and accumulate over time. Use the ewg.org for general product safety.
- Higher SPF doesn’t always translate to being able to stay out in the sun longer. More frequent applications of SPF 15 is often best.
- Many sunscreens can cause allergic reactions, so test a patch of skin first, especially with small children.
- Be careful if you make your own sunblocks. Your combinations are not tested and may be dangerous for your health and skin. There are many DIY recipes out there. The common bases and their SPF ratings are the following:
- Zinc Oxide SPF 2-20 depending on how much used (~2 tbsp per cup of sunscreen is common)
- Almond Oil- SPF ~ 5
- Coconut Oil- SPF 4-6
- Red Raspberry Seed Oil SPF 25-50
- Carrot Seed Oil – SPF 35-40
- Shea Butter – SPF 4-6
Kim HJ, Kang CK, Park H, Lee MG. Effects of vitamin D supplementation and circuit training on indices of obesity and insulin resistance in T2D and vitamin D deficient elderly women. J Exerc Nutrition Biochem. 2014 Sep;18(3):249-57.
Magnusson A, Partonen T. The diagnosis, symptomatology, and epidemiology of seasonal affective disorder. CNS Spectr. 2005 Aug;10(8):625-34;
Mackawy AM, Badawi ME. Association of vitamin D and vitamin D receptor gene polymorphisms with chronic inflammation, insulin resistance and metabolic syndrome components in type 2 diabetic Egyptian patients. Meta Gene. 2014 Aug 7;2:540-56.