Yes, this has been studied (ref. 1) and it's a healthy thing to do in
many ways,
but is very expensive and time-consuming. You will still need to
supplement,
for B12, possibly D and long-chain omega3 fatty acids (EPA+DHA) and maybe
even a few other things such as zinc and taurine.

It is probably a good idea to limit crucifers to 2.5% of daily calories
(ref 2)
and to include a wide variety of plant foods in many colors.

It is also probably a good idea to limit intake of oxalic acid. There is
a small
list of oxalic acid contents of common vegetables here:
http://www.nal.usda.gov/fnic/foodcomp/Data/Other/oxalic.html

Of all the leaf foods, lettuces are probably safest in large quantities
(ref 3).

Okinawans and some other Asian populations get the bulk of their
calories from sticky roots (not always orange, though, refs 4, 5) but
they also make at least modest use of animal food source, too..

You can track your micronutrient intakes using the pantry here:
http://www.nutritiondata.com/

It is a nice tool because it also tracks individual fatty and amino acids,
unlike some of the other online nutrient intake analysis programs.

You can also use the tools section to search on particular foods that
contain the highest or lowest levels of specified nutrients

Refts:

1.
Metabolism. 2001 Apr;50(4):494-503.    

    Effect of a very-high-fiber vegetable, fruit, and nut diet on serum
lipids and colonic function.

    Jenkins DJ, Kendall CW, Popovich DG, Vidgen E, Mehling CC, Vuksan
V, Ransom TP, Rao AV, Rosenberg-Zand R, Tariq N, Corey P, Jones PJ,
Raeini M, Story JA, Furumoto EJ, Illingworth DR, Pappu AS, Connelly PW.

    Clinical Nutrition and Risk Factor Modification Center, Department
of Medicine, Division of Endocrinology and Metabolism, St. Michael's
Hospital, Toronto, Quebec, Canada.

    We tested the effects of feeding a diet very high in fiber from
fruit and vegetables. The levels fed were those, which had originally
inspired the dietary fiber hypothesis related to colon cancer and heart
disease prevention and also may have been eaten early in human
evolution. Ten healthy volunteers each took 3 metabolic diets of 2 weeks
duration. The diets were: high-vegetable, fruit, and nut
(very-high-fiber, 55 g/1,000 kcal); starch-based containing cereals and
legumes (early agricultural diet); or low-fat (contemporary therapeutic
diet). All diets were intended to be weight-maintaining (mean intake,
2,577 kcal/d). Compared with the starch-based and low-fat diets, the
high-fiber vegetable diet resulted in the largest reduction in
low-density lipoprotein (LDL) cholesterol (33% +/- 4%, P <.001) and the
greatest fecal bile acid output (1.13 +/- 0.30 g/d, P =.002), fecal bulk
(906 +/- 130 g/d, P <.001), and fecal short-chain fatty acid outputs (78
+/- 13 mmol/d, P <.001). Nevertheless, due to the increase in fecal
bulk, the actual concentrations of fecal bile acids were lowest on the
vegetable diet (1.2 mg/g wet weight, P =.002). Maximum lipid reductions
occurred within 1 week. Urinary mevalonic acid excretion increased (P
=.036) on the high-vegetable diet reflecting large fecal steroid losses.
We conclude that very high-vegetable fiber intakes reduce risk factors
for cardiovascular disease and possibly colon cancer. Vegetable and
fruit fibers therefore warrant further detailed investigation. Copyright
2001 by W.B. Saunders Company

    Publication Types:

        * Clinical Trial
        * Randomized Controlled Trial

    PMID: 11288049 [PubMed - indexed for MEDLINE]

2.
Food Chem Toxicol. 1991 Dec;29(12):829-37.

Effects of high levels of brussels sprouts in the diet of rats.

de Groot AP, Willems MI, de Vos RH.

Department of Biological Toxicology, TNO Toxicology and Nutrition
Institute, Zeist, The Netherlands.

To examine the possible harmful effects of feeding Brussels sprouts to
rats, groups of 10 male, weanling rats received the non-dehydrated
vegetable in moist diets at levels providing 2.5-30% of the dry matter
for 4 wk. A first study comprised test diets with 15 and 30% of the dry
matter as uncooked or cooked Brussels sprouts and control diets without
and with 0.2% potassium thiocyanate (KSCN) for comparison. The second
study comprised diets with 0, 2.5, 5, 10 and 20% of the cooked vegetable
and diets with 0 and 20% of the cooked vegetable with extra iodine.
Diets with the uncooked vegetable contained considerably less intact
glucosinolates than did diets with the cooked product, probably as a
result of more extensive enzymatic degradation in the uncooked product.
Growth depression and decreased food intake, not accompanied by
decreased food efficiency, occurred in rats fed 10% or more dry matter
as Brussels sprouts. These findings were less marked with the cooked
than with the uncooked vegetable, probably because of unpalatability.
Decreased levels of blood haemoglobin and plasma thyroxin were found
with 15% or more Brussels sprouts. Prothrombin times were increased if
2.5% or more was fed. Thyroid stimulating hormone was increased by
feeding potassium thiocyanate, but not by feeding the vegetable.
Increased kidney weights and impaired kidney function not accompanied by
microscopic renal changes were observed in rats fed 10% or more Brussels
sprouts. Increased liver weights, which occurred from the 5% level, were
accompanied by microscopic hepatic changes only at feeding levels from
10% of the cooked vegetable. 'Morphological activation' of the thyroid
was increased with 10% or more of the cooked vegetable and with 0.2%
KSCN. Iodine supplementation of the diets did not influence the results
obtained with the vegetable. These studies indicated that 2.5% Brussels
sprouts dry matter in the diet was not without effect, and that the
thyroid characteristics were less sensitive to Brussels sprouts than
were other criteria examined.

PMID: 1765328 [PubMed - indexed for MEDLINE]

3.
Clin Nutr. 2004 Aug;23(4):605-14.    

    Health effect of vegetable-based diet: lettuce consumption improves
cholesterol metabolism and antioxidant status in the rat.

    Nicolle C, Cardinault N, Gueux E, Jaffrelo L, Rock E, Mazur A,
Amouroux P, Remesy C.

    Vilmorin, Clause & Cie, Chappes, France. cnicolle@clermont.inra.fr

    BACKGROUND & AIMS: It is often assumed that fruits and vegetables
contribute to protect against degenerative pathologies such as
cardiovascular diseases. Besides epidemiological observations,
scientific evidences for their mechanism of action are scarce. In the
present study, we investigated the mean term and post-prandial effects
of lettuce ingestion on lipid metabolism and antioxidant protection in
the rat. RESULTS: Feeding rats a 20% lettuce diet for 3 weeks resulted
in a decrease cholesterol LDL/HDL ratio and a marked decrease of liver
cholesterol levels (-41%). Concurrently, fecal total steroid excretion
increased (+44%) and apparent absorption of dietary cholesterol was
significantly depressed (-37%) by the lettuce diet. Lettuce diet also
displayed an improvement of vitamin E/TG ratio in plasma and limited
lipid peroxidation in heart as evidenced by TBARS. In post-prandial
experiment, lettuce intake significantly increased both ascorbic acid
and alpha-tocopherol plasma levels which contribute to improve plasma
antioxidant capacity within 2 h of consumption. Other lipid-soluble
antioxidants (lutein and vitamin E) may also improve the plasma
antioxidant capacity. CONCLUSION: Lettuce consumption increases the
total cholesterol end-products excretion and improves antioxidant status
due to the richness in antioxidants (vitamins C, E and carotenoids). In
our model, lettuce clearly shows a beneficial effect on lipid metabolism
and on tissue oxidation. Therefore regular consumption of lettuce should
contribute to improve protection against cardiovascular diseases.
Copyright 2003 Elsevier Ltd.

    PMID: 15297097 [PubMed - in process]

4.
 Asia Pac J Clin Nutr. 2001;10(2):159-64.    
    History and characteristics of Okinawan longevity food.

    Sho H.

    University of The Air Okinawa Study Center, Japan.

    Okinawan food culture in the Ryukyu island is one of the world's
most interesting culture because its consumers have the longest life
expectancies and low disability rates. It is a product of cultural
synthesis, with a core of Chinese food culture, inputs through food
trade with South-East Asia and the Pacific and strong Japanese
influences in eating style and presentation. The Satsamu sweet potato
provides the largest part of the energy intake (and contributes to
self-sufficiency), there is a wide array of plant foods including
seaweed (especially konbu) and soy, and of herbaceous plants,
accompanied by fish and pork, and by green tea and kohencha tea.
Infusing multiple foodstuff and drinking the broth is characteristic.
Raw sugar is eaten. The concept that 'food is medicine' and a high
regard accorded medical practice are also intrinsic of Okinawan culture.
Again, food-centered and ancestral festivities keeep the health
dimensions well-developed. Pork, konbu and tofu (soy bean-curd) are
indispensable ingredients in festival menus, and the combination of tofu
and seaweed are used everyday. Okinawan food culture is intimately
linked with an enduring belief of the system and highly developed social
structure and network.

    Publication Types:

        * Historical Article

    PMID: 11710358 [PubMed - indexed for MEDLINE]

5.
Chin Med J (Engl). 2001 Oct;114(10):1095-7.    
    A survey of the dietary nutritional composition of centenarians.

    Chen C.

    Department of Geriatrics, People's Hospital, Linyi 276003, China.

    OBJECTIVE: To make a survey of the nutritional composition of the
diets of centenarians. METHODS: Thirty-four centenarians were selected
as subjects. Retrospective surveys were made on the variety and amounts
of food consumed and their nutritional composition. Physical
examinations with laboratory tests such as cardiograms, ultrasonic B
rays, and blood, urine and hair tests were performed. Neutron activation
testing was done on hair content. The transmission turbidimetric method
was used to measure apolipoprotein content. RESULTS: The main food of
the centenarians showed the characteristics of low calories, protein and
fat but high fiber and mineral content. Laboratory results showed that
the content of the elements of Cu, Se and Mn in hair was higher (P <
0.01). Zn was normal. The apoA1/apoB100 ratio was higher than in the
control group (P < 0.01), and total cholesterol (TC) was lower than in
the control group (P < 0.01). CONCLUSIONS: The variety of diet and its
nutritional composition may be the main factors influencing not only the
content of elements in body, but also the levels of apoA1 and apoB100,
which may be helpful in preventing arteriosclerosis and forming and
maintaining immunity. The diet of these centenarians might aid in
preventing cardiovascular and cerebrovascular diseases and malignant tumors.

    PMID: 11677774 [PubMed - in process]

full paper
http://www.cmj.org/information/full.asp?pmid=2001101095