Wpływ diety laktoowowegetariańskiej na stężenie witaminy B12 w surowicy krwi – pięcioletnie badanie prospektywne (ang.).pdf - Rozne - katasza1982

ACTA Acta Sci. Pol., Technol. Aliment. 8(4) 2009, 71-76

ISSN 1644-0730 (print) ISSN 1889-9594 (online)

EFFECT OF LACTO-OVO-VEGETARIAN DIET

ON SERUM VITAMIN B12 CONCENTRATIONS

– FIVE-YEAR PROSPECTIVE STUDY

Edyta Mądry 1 , Aleksandra Lisowska 1 , Małgorzata Chabasińska 1 ,

Juliusz Przysławski 1 , Małgorzata Schlegel-Zawadzka 2 ,

Jarosław Walkowiak 1

1 Poznań University of Medical Sciences

2 Institute of Public Health, Collegium Medicum, Jagiellonian University in Krakow

Background. Avoiding of meat is the basic principle of vegetarian diet with several va-

riants existing. In the present study we have focused on lacto-ovo-vegetarian (LOV) diet

which includes dairy products and eggs. We have aimed to assess its long-term effect on

vitamin B12 status and intended to verify the influence of natural and vitamin B12-

-fortified food.

Material and methods. The prospective study was carried out comprising 16 healthy

omnivores (12 females, 4 males) who intentionally declared to follow strict LOV diet for

at least 5 years. The studied group was divided into 2 subgroups. First subgroup followed

LOV diet based entirely on natural products while the second consumed food fortified

with B12 vitamin. Evaluation of vitamin B12 concentration was performed before and af-

ter 6, 12, 24 and 60 months from LOV diet implementation.

Results. Five-years of LOV diet resulted in significant decrease of serum vitamin B12

concentrations in the whole studied group (p < 0.05). However, the significant drop of vi-

tamin B 12 level was in fact limited to the subgroup consuming exclusively natural prod-

ucts (p < 0.05). In none of the subjects abnormal serum vitamin B12 levels were observed.

Conclusions. Five-year lacto-ovo-vegetarian diet did not result in a risk of vitamin B12

deficiency in healthy subjects. However, the levels of serum vitamin B12 concentrations

in a subgroup consuming natural diet tend to be significantly lower as compared with the

group consuming fortified food. It confirms the need of follow-up (and potentially vita-

min B12 fortification of food and/or its supplementation) in long-term lacto-ovo-

-vegetarians.

Key words: lacto-ovo-vegetarians, omnivores, nutrition, vitamin B12, fortified food

Corresponding author – Adres do korespondencji: Dr Edyta Mądry, Department of Physiology

of Poznań University of Medical Sciences, Święcickiego 6, 60-781 Poznań, Poland, e-mail: edy-

tamadry@poczta.onet.pl

E. Mądry ...

INTRODUCTION

Vegetarianism is the practice of following a diet which excludes meat or meat and

other animal-derived products. The diet is very often linked with specific life-style and

usually adopted for ethical, health, environmental, culture or religious reasons. Most

of vegetarians in the world do not eat meat for the economic situation [Asok 2003].

Regardless of the cause, the issue concerns huge part of the world’s population and in

the western countries is presently more popular than ever before.

The number of vegetarians is continuing to grow at an astonishing rate. In UK dur-

ing the last ten years it has been more than doubled, reaching 7% of all British and 12%

of adolescents and young adults. In other European countries vegetarian population

varies from 0.3% in Portugal to 4.3% in Netherlands. Data from 2008 put the number of

U.S. adult vegetarians at 7.3 million (3.2%), while in Poland more than 1% declare

vegetarianism [Herrmann and Knapp 2002]. A 2006 survey in India found that 40% of

the population (399 million people) are vegetarians [www.raw-food-health.net 2009].

There are many reports about beneficial effects of vegetarian diet on general health.

People following modern vegetarian diet demonstrate lower risk of obesity, osteoporosis

and cardiovascular diseases, decreased total cholesterol level and declined mortality due

to some cancers [Messina and Burke 1997, Key et al. 2009, Newby et al. 2005, Obeid et

al. 2002]. However, the elimination of animal products from the diet diminishes the

intake of some essential nutrients, such as vitamin B 12, calcium, iron, zinc or selected

amino acids [Hronek and Kudlackova 2005, Janelle and Barr 1995, Suter and Moser

2005]. Lower plasma vitamin B 12 levels in vegetarians than in omnivores have been

clearly demonstrated [Huang et al. 2003, Mezzano et al. 2000, Obeid et al. 2002]. Nev-

ertheless, the importance of adequate vitamin B 12 status is often underestimated because

the dietary intake of vitamin B 12 is usually far above dietary reference intakes in mixed

Western diets and overt clinical manifestation of its deficiency has been so far a rare

clinical condition in children and young adults. Vitamin B 12 (cobalamin) functions

as a coenzyme for a critical methyl transfer reaction that converts homocysteine to me-

thionine and for a separate reaction that converts L-methylmalonyl-coenzyme A (CoA)

to succinyl-CoA. Its deficiency results in impairment of the above enzymes and may

result in elevated levels, respectively of homocysteine and methylmalonic acid.

Increased serum homocysteine level above 15 µmol/l is strongly related to the risk of

ischemic heart disease, deep vein thrombosis and stroke [Wald et al. 2002].

Nowadays there are few long-term prospective studies assessing the impact of vege-

tarian diets on vitamin B12 status. Avoiding of meat is the basic principle of all vegeta-

rian diets but there are several variants [Abdulla et al. 1981]. In the present study

we have focused on lacto-ovo-vegetarian diet that includes dairy products and eggs. We

have aimed to assess its long-term effect on vitamin B12 status and intended to verify

the influence of natural and vitamin B12-fortified food.

MATERIAL AND METHODS

The prospective study was carried out comprising 16 healthy omnivores (12 fe-

males, 4 males) who intentionally declare to follow strict lacto-ovo-vegetarian diet for

www.food.actapol.net

Effect of lacto-ovo-vegetarian diet on serum vitamin B12 concentrations ...

Table 1. Characteristics of the studied group

Parameter

Range

Mean +SEM (median)

Age (years)

21-26

23.5 ±0.4 (24.0)

BMI

18.5-26.6

21.6 0.6 (21.2)

at least 5 years (Table 1). The studied group was divided into 2 subgroups. First sub-

group followed lacto-ovo-vegetarian diet based entirely on natural products while the

second consumed the food fortified in B12 vitamin.

In all subjects serum vitamin B12 levels were determined before and after 6, 12, 24

and 60 months from the implementation of the diet. Vitamin B12 was assessed with the

use of chemiluminescence immunoassay. (Immunolite-Vitamin B12 test, Diagnostic

Products Corporation; IMX Foliate Calibration, Abbott). Values lower than 193 pg/ml

were considered as abnormal.

The differences in B12 concentrations were analysed with the use of Friedman test

(dependent samples). The level of statistical significance was set at p < 0.05. The study

protocol was approved by Bioethics Committee of Poznań University of Medical

Sciences.

RESULTS

Five-year lacto-ovo-vegetarian diet resulted in a significant decrease of serum vita-

min B12 concentrations in the whole studied group (p < 0.05). However, the significant

drop of vitamin levels was in fact limited to the subgroup consuming exclusively natural

products (p < 0.05). In none of the subjects abnormal serum vitamin B12 levels were

observed (Table 2).

Table 2. Serum Vitamin B12 concentrations within 60 months period of the study

Vitamin B12, pg/ml

Type of diet

(month of the

observation)

subgroups

whole group

natural diet*

fortified products

mean ±SEM

(median)

range

mean ±SEM

(median)

range

mean ±SEM

(median)

range

Omnivore (0)

396 ±34 (372) 211-712 390 ±48 (307) 211-712 403 ±17 (402) 306-534

LOV (6)

372 ±29 (344) 197-622 353 ±35 (299) 197-622 391 ±20 (377) 299-534

LOV (12)

346 ±23 (345) 205-512 321 ±27 (299) 205-512 371 ±20 (387) 267-498

LOV (24)

342 ±22 (328) 203-488 326 ±26 (290) 203-488 358 ±19 (361) 254-458

LOV (60)

345 ±24 (330) 196-475 310 ±27 (260) 196-455 380 ±20 (384) 249-462

LOV – lacto-ovo-vegetarian.

Acta Scientiarum Polonorum, Technologia Alimentaria 8(4) 2009

E. Mądry ...

DISCUSSION

Despite existing evidence that well-planned vegetarian diets provide numerous

health benefits and are appropriate for all stages of the life cycle it is also known that

animal foods provide micronutrients that are nonexistent or available only in limited

amounts in plant foods [Elmadfa and Singer 2009]. The above facts indicate the possi-

bility of insufficient intake of some macro, microelements and vitamins in diet based on

fruits and vegetables with elimination of meat. The problem concerns zinc, calcium,

iron, iodine some amino acids, vitamins B12 and D3 [Larsson and Johansson 2005,

Miller et al. 1991].

The only reliable unfortified sources of vitamin B12 in human diet are meat, dairy

products and eggs [Linnel and Mattews 1984]. Thus different vegetarian diets could

potentially exert varied effects. In a cross-sectional study Chabasińska et al. have dem-

onstrated that type of vegetarian diet and length of its application influences vitamin B 12

body resources [Chabasińska et al. 2008]. Allen underlined that inadequate intake, due

to low consumption of animal-source foods, is the main cause of low serum vitamin

B12 in younger adults [Allen 2009]. Therefore, in the current study we have followed

lacto-ovo-vegetarians subjects for 5 years. Although changes were statistically signifi-

cant, in none of the subjects abnormal vitamin B12 concentrations were stated. Our

finding confirms Allen’s observations that low intakes of animal-source foods, such as

the ones that occur in some lacto-ovo vegetarians may cause vitamin B12 depletion [Allen

2009]. Cobalamin can be stored in small amounts by humans. Total body store is about

2-5 mg in adults, around 80% of it is stored in the liver. Vitamin B12 is excreted in the bile

and in healthy subjects is effectively reabsorbed (entherohepatic circulation). Therefore,

diets with low content of vitamin B12 do not lead in a short period of time to its deficien-

cy. This process may take even up to 20 years. On the contrary, malabsorption may create

such a situation in 3 years time [Dwyer 1999, Linnel and Mattews 1984]. It should be

thoroughly considered since some of vegetarians started their diet due to certain gastroin-

testinal complaints. Early noticeable symptoms of vitamin B 12 deficiency are nonspecific

(unusual fatigue, digestion problems, frequent upper respiratory infections) and can be

very easily ignored by patients as well as medical professionals.

In view of our results we agree that vegetarians must be advised to carefully plan

their diets and to monitor their plasma vitamin B12 on a regular basis to facilitate early

detection of low cobalamin status [Elmadfa and Singer 2009]. In the present study we

proved that fortified foods potentially could in a significant degree influence vitamin

B12 resources. Hoey et al documented that voluntary consumption of fortified food is

associated with an increase in dietary intake of B12 vitamin and has potential beneficial

effects on health. However, those who do not consume fortified foods regularly may

have insufficient B12 vitamin status to achieve the known and potential health benefits

[Hoey et al. 2007]. A wide range of B12 fortified foods are available. Fermented soya

products, seaweeds, and algae have all been suggested as containing significant B12

contents. The other option is simple vitamin B12 supplementation [Hoey et al. 2007].

CONCLUSIONS

Five-year lacto-ovo-vegetarian diet did not result in the risk of vitamin B12 defi-

ciency in healthy subjects. Nevertheless, serum vitamin B12 concentrations in the sub-

www.food.actapol.net

Effect of lacto-ovo-vegetarian diet on serum vitamin B12 concentrations ...

group consuming natural diet were significantly lower as compared with the group

consuming fortified food. It confirms the need of follow-up (and potentially vitamin

B12 fortification of food and/or its supplementation) in long-term lacto-ovo-vegetarians.

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Acta Scientiarum Polonorum, Technologia Alimentaria 8(4) 2009

Wpływ diety laktoowowegetariańskiej na stężenie witaminy B12 w surowicy krwi – pięcioletnie badanie prospektywne (ang.).pdf

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