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(Seasonal affective depression - SAD) 


Winter tiredness due to lack of sunlight is known as seasonal affective depression (SAD) and the Winter blues.


It can be prevented by taking vitamins D and K, using a daylight lamp and having a walk outdoors roundabout midday.  

Taking vitamin D unsupported by vitamin K can cause calcification of the blood vessels and increase the risk of heart disease. Also, combining with vitamin K increases the effectiveness of vitamin D.


A recommendable vitamin D/vitamin K preparation is K-Right (by Jarrow), one capsule to be taken daily. This product is available from iHerb (USA) - cost about £25 for 60 capsules. 

Content of each K-Right softgel

Vitamin D3 (Cholecalciferol) 50 micrograms (2000 i.u.) 

Vitamin K1 (phylloquinone) 500 micrograms

Vitamin K2 (MK-4) 500 micrograms

Vitamin K2 (as naturel MK-7) 180 micrograms



Do not self-medicate with vitamin K if you are pregnant, trying to conceive or taking anticoagulants such as warfarin and coumadin.

For optimal immune system support, it is advisable to take extra vitamin D. E.g. Vitamin D3 High Strength Tablets 5000 i.u. from Nutri (0800 043 5777).


Suggested daily supplementation for optimal immune system support during the Winter.

K-Right (iHerb)- one capsule daily.

Vitamin D3 5000 i.u (Nutri). - 2 tablets daily. 

Daylight lamp and SAD

Although vitamin D supports the immune system, research in Scandinavia has shown that it does not prevent Winter tiredness due to lack of daylight. It is therefore advisable to use a daylight lamp (goggles are unnecessary) and to spend time outdoors when the sun is at its highest roundabout midday.  

Daylight lamp

SAD Light, Elfeland SAD Light Therapy Lamp 10,000 Lux 6500K LED Sun Light Energy Lamp with Rotatable Holder & UK Adapter, Brightness Adjustable Ultrathin Sad Lights for Depression with Timer Setting.

About £30.

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