Sun exposure

• In 2011 the British Journal of Dermatology published a study in which 20 patients with moderate-to-severe psoriasis showed clinical improvement in psoriasis as well as rapid reduction in local and systemic inflammation after 16 days of controlled sun exposure. [Source]

Tanning Beds

• In 2003 Archives of Dermatology published a 12-week, 2-part study in which daily acitretin (drug used to treat psoriasis) therapy combined with commercial tanning bed UV exposure for 4 to 5 days per week resulted in clearance or near clearance of moderate-to-severe plaque-type psoriasis in 19 of 23 subjects in a retrospective trial and a 79 percent average improvement in a prospective trial of 17 patients. [Source]

Omega-3 fatty acids

• In 2002 the British Journal of Nutrition published a study in which psoriasis patients saw greater symptom improvement when treated intravenously with omega-3 fatty acids when compared to an omega-6-based treatment. [Source]

Vitamin D

• In 2013 Dermato-endocrinology published a study in which 9 patients with psoriasis and 16 patients with vitiligo (loss of skin pigmentation) were treated with 35000 IU’s of vitamin D3 daily for 6 months, combined with a low-calcium diet. At the end of the study all 9 psoriasis patients saw significant improvement, while 14 of 16 vitiligo patients saw a 25 to 75 percent repigmentation. [Source] 

Phototherapy

• In 2010 Archives of Dermatology published a 4-week study in which 30 patients with psoriasis were treated with narrow-band UV-B 3 times per week. At the end of the study all patients in the treatment group had sufficient vitamin D levels while 75 percent of a control group remained vitamin-D-insufficient. The researchers concluded that narrow band UV-B effectively increases serum vitamin D, while clearing psoriasis. [Source] 
• In 2007 Clinical and Experimental Dermatology published a study which used targeted UVB lamps to treat plaque psoriasis in 28 patients. After 16 weeks and between 6 and 18 sessions, 36 percent of patients had a greater than 75 percent improvement based on the psoriasis severity index, with 21 percent of patients showing complete clearance. [Source]
• In 2005 Archives of Dermatology published a 14-patient study in which specific doses of targeted UVB phototherapy administered 3 times weekly for a period of 4 weeks produced clearance in 77 percent of patients suffering from localized psoriasis. [Source]

Phototherapy with Methotrexate

• In 2006 the Journal of the American Academy of Dermatology published a study which showed that narrowband UV-B administered with methotrexate cleared plaque psoriasis significantly faster than narrowband UV-B combined with a placebo.  [Source]

B12 cream containing avocado oil

• In 2001 Dermatology published a study in which vitamin B12 cream containing avocado oil was compared with calcipotriol (a vitamin D derivative used to treat psoriasis) for the treatment of plaque psoriasis in 13 patents. The effects of calcipotriol reached a peak in the first 4 weeks and then begin to subside, while the vitamin B12/avocado cream showed consistent benefits over the 12-week study period. Additionally, both patients and researchers assessed the B12/avocado treatment as having significantly better tolerability compared to calcipotriol, making it a potential long-term treatment option. [Source]

Physical exercise and diet

• In 2014 the British Journal of Dermatology published a 303-subject study in which overweight or obese patients with moderate-to-severe chronic plaque psoriasis who were not able to achieve skin clearance with standard treatments reduced psoriasis severity by adhering to a 20-week dietary program combined with physical exercise. [Source]

Weight loss

• In 2013 JAMA Dermatology published a study in which 60 overweight patients with psoriasis were assigned to a control group or a low-calorie diet (800-1000 kcal/d) for 8 weeks, followed by 8 weeks of reintroduction of normal food intake. The low-calorie group experienced clinical improvements in psoriasis compared to the control group. [Source]   
• In 2015 the International Journal of Obesity published a meta-analysis of 5 clinical trials for which the data showed non-surgical weight loss is associated with a reduction in psoriasis severity in overweight and obese patients. [Source] 
• In 2008 the American Journal of Clinical Nutrition published a 24-week study in which 61 obese patients with moderate-to-severe psoriasis were treated with either 2.5 mg per day cyclosporine alone or combined with a low-calorie diet. The results showed that the low-calorie-diet group responded better to low-dose cyclosporine. [Source] 
• In 2013 Dermatology Research and Practice published a 24-week clinical trial in which 10 patients with chronic plaque-type psoriasis were assigned to a low-calorie diet along with a topical treatment. After 12 weeks average body weight lost was 9.6 percent. Half of the study participants saw a 50 percent or greater improvement in psoriasis severity scores. [Source] 
• In 2016 The American Journal of Clinical Nutrition published a study involving 32 psoriasis patients which demonstrated that a 16-week low-calorie diet resulting in an average weight loss of 33 lbs lead to positive, lasting effects on psoriasis severity. [Source]
• In 2014 Expert Opinion in Biological Therapy published a 262-patient study in which weight loss induced by a 1000 calorie (or less) per day diet for 8 weeks (averaging 28 total lbs lost) improved effectiveness of psoriasis drugs when compared to a control group who consumed a normal diet. [Source] 
• In 2014 Annals of the Rheumatoid Diseases published a study involving 126 subjects which found that overweight patients who successfully lost at least 5 percent of their body weight achieved improved results using psoriasis treatment drugs (TNFa blockers). Patients who lost greater than 10 percent body weight saw the most significant improvements, with 60 percent of these patients achieving minimal disease activity (MDA). [Source]

Hypertension

• In 2010 Acta Dermato-venereologica published a case-control study based on 12,502 psoriasis patients and 24,285 controls which found a significant association between hypertension and psoriasis. The authors of the study recommend that patients with psoriasis be routinely screened for hypertension. [Source]

Alcohol consumption

• In 2009 Clinical and Experimental Dermatology published a study which found that 15 out of 100 patients with alcoholic liver disease had a history of psoriasis. Based on the sample, prevalence of psoriasis in patients who misuse alcohol is significantly higher than the 1 to 3 percent estimated among the general population. [Source] 
• In 2017 The British Journal of Dermatology published a 609-patient study which found that alcohol use disorders (UAD) were significantly more prevalent in patients with inflammatory skin diseases – with UAD being prevalent in 30 percent of patients with psoriasis and 33 percent of patients with eczema. [Source]

NAFLD

• In 2009 the Journal of Hepatology published a study which found that non-alcoholic fatty liver disease (NAFLD) was present in nearly half of a sample of 130 patients with psoriasis. The presence of NAFLD was strongly correlated with psoriasis severity. [Source]  

Sleep disorders

• In 2016 Sleep Medicine Reviews published a review of 33 studies which found that obstructive sleep apnea was present in between 36 to 81 percent of individuals affected by psoriasis compared to 2 to 4 percent of the general population. [Source]

Smoking

• In 2014 the Indian Journal of Dermatology published a study involving 338 psoriasis patients which found that tobacco smoking was associated with increased psoriasis severity in adult males – though no link was found between alcohol use and psoriasis. [Source]

Smoking and alcohol intake

• In 2010 Dermatology published a retrospective study which found that, in a group of 1203 patients with severe psoriasis, 43 percent were active smokers. Both smoking and alcohol intake were independently associated with severe forms of psoriasis, with disease severity correlating with smoking in both males and females. [Source]