A placebo tablet was the attention control intervention for the folic acid + vitamin B12 intervention group. Participants received 1 bottle x 200 tablets in 6-month supplies at baseline, 6 months, 12 months, and 18 months. Adherence was monitored by telephone interviews (6 weeks, 6-, 12-, and 24 months) and 10 brief telephone tracking calls (1 - 5 weeks, and 4-, 8-, 13-, 18-, and 22-months) during which participants counted their left-over tablets.

The attention control intervention for the physical activity intervention was printed nutrition literacy and included information concerning the recommended dietary guidelines for older Australians, as well as strategies and additional information to facilitate beneficial dietary behaviours. The same procedure was adhered to as the physical activity intervention to ensure adequate attention control. Participants in the nutrition promotion intervention received 5 brief telephone calls from an interviewer to facilitate adherence to the intervention, and to offer support and clarification of the materials. Participants received five further brief telephone calls as well as nutrition newsletters that were delivered via postal mail at 4-, 8-, 13-, 18-, and 22- months.

Pain and Arthritis Information was used as the attention control intervention for the MHL intervention and comprised 10 modules. Modules 1 to 5 were contained in an Arthritis Australia consumer guide for arthritis management. Modules 6 to 10 were a series of information pamphlets on pain management, osteoporosis and falls prevention. The delivery of the Pain Information was identical to the MHL intervention with Modules 1 to 5 distributed via postal mail in five consecutive weeks (1-5 weeks), while the remaining intervention modules were delivered at 4- (Module 6), 8- (Module 7), 13- (Module 8), 18- (Module 9), and 22- months (Module 10). Participants also received 10 brief calls from a telephone interviewer that coincided with receiving the print intervention materials.

Individuals in the Physical Activity Promotion group received a manual designed to promote older individuals' physical activity participation to the level recommended to gain both physical and mental health benefits. The framework of the physical activity manual was informed by social cognitive theory and the transtheoretical model, and comprised five sections that reflect stages of behaviour change, including; precontemplation, contemplation, preparation, action, and maintenance. The manual contained evidence-based strategies and skills to assist people in increasing their physical activity levels. Participants received a pedometer at the commencement of the intervention as pedometry step / minute values are useful as an indicator of moderate to vigorous physical activity with total number of steps for one week recorded during the brief telephone calls at 1-5 weeks, and 4-, 8-, 13-, 18-, and 22- months.

Comprises 10 modules, with nine of these specifically written for older adults. Modules 1 to 5 comprised information on depression and the evidence-based treatment for older adults. The additional MHL modules were booklets addressing evidence-based strategies and treatments for depression. It was delivered in a way to foster support and ensure that participants worked through the material systematically. Modules 1 to 5 were delivered in consecutive weeks as previous research indicates that the maximum impact of MHL on depressive symptoms may occur within the first six weeks of the intervention. Telephone interviewers contacted participants once a week for 5 consecutive weeks to motivate and support participants. There were an additional 5 check-in telephone calls, and Modules 6 to 10 of the MHL material that were delivered via postal mail at 4- (Module 6), 8- (Module 7), 13- (Module 8), 18- (Module 9), and 22- months (Module 10).

A placebo tablet was the attention control intervention for the folic acid + vitamin B12 intervention group. Participants received 1 bottle x 200 tablets in 6-month supplies at baseline, 6 months, 12 months, and 18 months. Adherence was monitored by telephone interviews (6 weeks, 6-, 12-, and 24 months) and 10 brief telephone tracking calls (1 - 5 weeks, and 4-, 8-, 13-, 18-, and 22-months) during which participants counted their left-over tablets.

The attention control intervention for the physical activity intervention was printed nutrition literacy and included information concerning the recommended dietary guidelines for older Australians, as well as strategies and additional information to facilitate beneficial dietary behaviours. The same procedure was adhered to as the physical activity intervention to ensure adequate attention control. Participants in the nutrition promotion intervention received 5 brief telephone calls from an interviewer to facilitate adherence to the intervention, and to offer support and clarification of the materials. Participants received five further brief telephone calls as well as nutrition newsletters that were delivered via postal mail at 4-, 8-, 13-, 18-, and 22- months.

Pain and Arthritis Information was used as the attention control intervention for the MHL intervention and comprised 10 modules. Modules 1 to 5 were contained in an Arthritis Australia consumer guide for arthritis management. Modules 6 to 10 were a series of information pamphlets on pain management, osteoporosis and falls prevention. The delivery of the Pain Information was identical to the MHL intervention with Modules 1 to 5 distributed via postal mail in five consecutive weeks (1-5 weeks), while the remaining intervention modules were delivered at 4- (Module 6), 8- (Module 7), 13- (Module 8), 18- (Module 9), and 22- months (Module 10). Participants also received 10 brief calls from a telephone interviewer that coincided with receiving the print intervention materials.

The modified Telephone Interview of Cognitive Status has a max. total score= 39, and comprises 4 domains: orientation; recent memory and delayed recall; attention; and, semantic memory. It has excellent discrimination in cognitive performance in the general population. Processing speed was measured (Brief Test of Adult Cognition-Telephone) with the task to count backwards quickly from 100 by 1's for 30 seconds The Informant Questionnaire on Cognitive Decline in the Elderly was given at 2yr FU to a person who had known the participant for > 2yrs. It measures cognitive decline and dementia.

A health checklist was given to determine current health status with items addressing the following health domains: cardiovascular, pulmonary, musculoskeletal, psychiatric, vision, and renal health; cancer, diabetes, and epilepsy. Blood collections were also used at baseline, 12- and 24 months to further investigate health including: thyroid stimulating hormone; liver and kidney function; fasting cholesterol and blood glucose; C-reactive protein; and haematological parameters.

Serum vitamin B12 was measured using chemiluminscent microparticle assays (Architect i2000, Abbott Laboratories). This allowed a check on whether participants were taking the supplements, and to initially to comply with inclusion/exclusion criteria.

Red cell folate was measured using chemiluminscent microparticle assays (Architect i2000, Abbott Laboratories). This allowed a check on whether participants were taking the supplements, and as part of the initial screening process to comply with our inclusion/exclusion criteria.

A fluorescence polarization immunoassay was used for the quantitative determination of total L-homocysteine in plasma (AxSYM, Abbott Laboratories). This allowed us to establish any changes in Hcy concentration.