Betaine is a non-essential nutrient which performs several important physiological functions in organisms. Abundant data exist to suggest that betaine has a potential for prevention of chronic diseases and that its dietary intake may contribute to overall health enhancement.
1. Introduction
Betaine (N,N,N-trimethylglycine, glycine betaine) is an organic nitrogenous compound, found for the first time in sugar beet juice (Beta vulgaris).
Betaine is a zwitterion of quaternary ammonium which is still named trimethylglycine and glycine betaine (
Figure 1). It is a methyl derivative of the amino acid glycine ((CH
3)
3N
+CH
2COO
− and molecular weight 117.2). It is characterized as methylamine due to its three free methyl groups
[1].
Figure 1. Betaine chemical structure.
Various analogues of glycine betaine exist in plants: proline betaine (stachydrine), trigonelline, arsenobetaine, betonicine, butirobetaine, ergothionine, propionobetaine, and sulfur analogues. The sulfur analogues are several in type: β-alaninebetaine, dimethylsulfonioacetate, and dimethylsulfoniopropionate (DMSP). The food survey study by de Zwart et al.
[2] showed that only some betaine analogues were present in food at appreciable levels (>10 µg/g)—glycine betaine, proline betaine, trigonelline, and DMSP. Slow et al.
[3] indicated glycine betaine as dominant in grain products, proline betaine in citruses, and trigonelline in coffee. Most recently, some rare forms of betaine were identified in the grains of most common cereals: pipercolic acid betaine in rye flour and valine betaine and glutamine betaine in flours of barley, rye, oat, durum, and winter wheat
[4]. The content of betaine analogues was found to be vastly variable in grains; higher betaine levels seem to be induced by plant growth under stress conditions (drought, salt stress, cold, freezing, hypoxia, etc.)
[2,3][2][3]. Since the potential health effects of betaine analogues, particularly trigonelline and proline, have not yet been fully resolved, currently only glycine betaine has dietary relevance.
Betaine represents a bioactive compound that has significant physiological functions in the human organism as an osmolite and donor of methyl groups for many biochemical processes. As such, it is indispensable to preserve the health of kidneys, liver, and heart
[5]. This compound has an important role in preventing and treating many chronic diseases, among which lowering of plasma homocysteine levels has gained the most attention
[5,6,7][5][6][7]. High serum homocysteine levels have been associated with increased risk for cardiovascular diseases (stroke, heart attack, atherosclerosis), cancer, peripheral neuropathy, etc. Moreover, betaine has been shown to improve athletic performance by enhancing muscle endurance
[7,8][7][8].
2. Cereal Grains as a Source of Betaine
Data on the distribution of betaine in various cereals and pseudocereals are scarce and there is definitely a lack of detailed study. Most data come from various studies that were focused on estimation of betaine dietary intake. Nevertheless, available studies report on wide variations in betaine content in cereals. Different types of cereals may have different amounts of betaine
[22][9]. The following ranges were found by de Zwart et al.
[2]: 270–1110 µg/g (dry solids) in wheat flour, and 200–1000 µg/g in oats. More detailed overview of betaine levels in various cereals and pseudocereals from different studies is displayed in
Table 1. The displayed data showed that betaine content spanned in wide ranges within the studied grains. According to Corol et al.
[22][9], betaine content in cereals varies depending on multiple factors including genotype and environmental differences such as geographical and/or year-to-year variations and their interactions with genotype. This study revealed a three-fold difference in glycine betaine content within bread wheat genotypes and a 3.8-fold difference across six environments. The highest glycine betaine levels were found in Hungarian wheat grains whereas the lowest in those grown in the UK
[22][9]. Slow et al.
[3] and de Zwart et al.
[2] indicated that the level of betaine depends on the level of stress under which the crop grows. This is due to osmoprotectant and cryoprotectant function of betaine. For example, growth under drought can cause higher levels of betaine compared to well-watered crops.
Table 1. Betaine content in different samples of cereals and pseudocereals.
Cereals and Pseudocereals
|
Betaine
|
References
|
(µg/g Dry Weight)
|
(µg/g Dry Weight)
|
Wheat (Triticum aestivum)
|
|
Bread
| |
|
|
], proso millet 280 µg/g
[23][11]. Buckwheat is a frequent ingredient in gluten-free products. According to Ross et al.
[11][13], buckwheat was among those ingredients low in betaine (<20 µg/g) although as high as 390 µg/g betaine was found in buckwheat uncooked pasta (
Table 3).
Table 3. Betaine content in gluten-free products.
Product
|
Betaine Content
(µg/g Dry Weight)
|
References
|
Bread and biscuits
|
|
|
raw grain
|
1150–1320
|
[18][10]
|
rye bread
|
855–1377
|
[11][13]
|
|
490–574
|
[ |
|
gluten-free crispbread
|
9–107
|
[11][13]
|
wholegrain spelt
|
savory biscuits
|
n.d.–104
| 23][11]
|
| 913
|
[11][13]
|
[23][11]
|
bran
|
5047–5383
|
wholemeal
|
|
wholegrain gluten-free bread
| 670–790
|
12–68
[23][11]
|
| [ | 3]
|
[11][13]
|
|
wholegrain
|
oatmeal biscuits |
2717
|
|
[21][12]
|
| 499–781
|
[11 |
3
][13]
|
[11][13]
|
|
2300–7200
|
gluten-free flour enriched with fibers |
| [3]
|
|
560–620
|
[ |
1
3]
|
[11][ |
aleurone
|
4538–6242
|
multigrain
|
247–678
|
[11][13]
|
13 | ] |
|
[11][13]
|
germ
|
|
white (refined)
| 3414
|
360–520
[11][13]
|
wholegrain flour
|
792
|
[11][13]
|
| [ | 21][12]
|
sweet biscuits
|
n.d.
|
[21][12]
|
flour mixture for gluten-free bread
|
n.d.
|
[21][12]
|
gluten-free cookies with almonds, crackers, salty sticks
|
n.d.
|
[21][12]
|
|
730 *
|
[ |
expanded maize
| 24 | ][14]
|
| n.d.
|
[21][12]
|
|
604
|
[ |
Pasta
| 19 | ][15]
|
|
540
|
[23][11]
|
refined flour
|
718 *
|
[25][16]
|
|
700 *
|
[24][14]
|
|
415–593
|
[21,23][12][11]
|
|
398
|
[11][13]
|
|
durum wheat pasta, uncooked
|
188
|
[21][12]
|
| 180 *
|
[4]
|
|
141.2
|
[19][15]
|
flour (not specified by origin)
|
270–1110
|
[2]
|
Wheat Emmer (T. dicoccum)
|
|
|
|
| [3]
|
|
174–287
|
[11][13]
|
raw grain
|
various (white, sourdough)
|
|
one–egg spelt pasta
830–940
|
|
243–516
[18][ |
[11][13]
|
barley pasta
|
211
|
[11][13]
|
|
noodles with egg, enriched, uncooked
|
1300 *
|
[24][14]
|
buckwheat pasta, uncooked
|
390
|
[23][11]
|
|
382
|
[11][13]
|
|
175
|
[21][12]
|
maize-based pasta
|
2–20
|
[11][13]
|
maize and rice-based pasta, uncooked
|
n.d.
|
[21][12]
|
rice-based pasta, uncooked
|
n.d.
|
[21][12]
|
10 |
Breakfast cereals and related products
|
|
|
soy bran
|
182
|
[21][12]
|
] |
unseasoned popcorn
|
19
|
[11][13]
|
|
cornflakes
|
14
|
[11][13]
|
refined flour
|
|
buckwheat flakes
|
195 *
|
10
|
[4]
|
| [ | 11][13]
|
Wheat Einkorn (T. monococcum)
|
noodles with egg, enriched, cooked |
rice-based breakfast cereals
| |
|
| 4–5
|
[11][13]
|
refined flour
|
|
367.3 *
|
|
expanded rice
|
190 *
|
n.d.
[4]
|
| [ | 24][14]
|
| [ | 21][12]
Durum wheat (T. durum)
|
|
|
refined couscous
|
691
|
[11][13]
|
semolina
|
1227
|
[23][11]
|
bulghur
|
1311
|
[11][13]
|
|
483
|
[21][12]
|
cooked bulghur
|
830 *
|
[24][14]
|
|
Breakfast cereals
|
683
|
[11][13]
|
310–590 * |
|
[24][14]
|
|
|
refined flour
|
253–303
|
|
ready-to-eat wheat germ, toasted, plain
|
4100 *
| [23][11]
|
| [ | 24][14]
|
|
310
|
[ |
ready-to-eat wheat bran, toasted
| 21 | ][12]
|
| 3200 *
|
[24][14]
|
wholegrain flour
|
|
713
|
wholegrain rye flakes
[ |
1640
11][13]
|
| [ | 11][13]
|
|
|
wholegrain wheat-based cereals
| 245 *
|
732–915
|
[4]
|
| [ | 11][13]
|
Spelt wheat (T. aestivum ssp. spelta)
|
|
|
wholegrain oat and wheat-based muesli
|
310
|
[11][13]
|
raw grain
|
|
wholegrain oat-based muesli
| 973–2723
|
|
117–226
[23][11]
|
| [ | 11][13]
|
|
565–714
|
breakfast cereals, not specified
|
180–300
|
[21][12]
|
| [ | 21][12]
|
wholegrain flour
|
1296–1442
|
muesli bar
|
171
|
[23][11]
|
| [ | 11][13]
|
|
1370–1430
|
[18][10]
|
wholegrain porridge oats
|
128–167
|
[11][13]
|
refined flour
|
978
|
[11][13]
|
|
522–593
|
[23][11]
|
|
extruded whole grain oat cereals
|
73–91
|
[11][13]410 |
|
[21][12]
|
|
cereal bar
|
74–75
|
[11][13 |
Kamut wheat, Khorasan (T. turgidum ssp. turanicum)
|
|
|
] |
|
various ready-to-eat cereals
|
7–3600 * |
raw grains
|
1100
|
[24][14]
|
|
Triticale (xTriticosecale)
|
|
|
raw grain
|
986–1030
|
[23][11]
|
| [ | 24][14]
|
Snacks, cookies, crackers, crispbread, cakes, pastry
|
|
|
wholegrain rye crispbread
|
1428–1527
|
[11][13]
|
frozen, read-to-eat pancakes
|
690–720 *
|
[24][14]
|
Rye |
wholegrain wheat crackers
|
293–649
|
[11][13]
|
|
|
crackers, classic, saltines, cheese
|
| |
340–580 * |
|
[24][14]
|
raw grain
|
2213
|
|
wholegrain wheat rusks
|
556–564
| [23][11]
|
| [ | 11][13]
|
|
wholegrain wheat muffin
|
1530–1760
|
437–501
[18][10]
|
| [ | 11][13]
|
|
various commercial cakes
|
444
|
190–480 *
[21][12]
|
| [ | 24][14]
|
bran
|
1651
|
|
wholegrain wheat biscuit
| [ | 19][15]
|
| 425
|
[21][12]
|
refined flour
|
310 *
|
[4]
|
Graham cookies
|
390 *
|
[24][14]
|
wholegrain flour
|
1500 *
|
doughnuts
|
| [ |
270–380 *
24][14]
|
| [ | 24][14]
|
|
1182
|
English muffins
|
220–360 *
|
[23][11]
|
| [ | 24][14]
|
|
extruded spelt |
986
|
|
308
|
[21][12]
|
| [ | 21][12]
|
Barley
|
refined wheat crackers | |
|
258–332
| |
| [ | 11][13]
|
raw grain
|
460
|
[18][10]
|
raw grain from naked var.
|
|
digestive biscuit
|
271–309
|
[11][13]
980
|
[18][10]
|
apple pie, commercial
|
160 *
|
[24][14]
|
wholegrain flour
|
biscuit
|
776–1023
|
[23][11]
|
| 4–144
|
[11][13]
|
|
|
Danish pastry, fruit enriched
| 779
|
|
140 *
[21][12]
|
| [ | 24][14]
|
refined flour
|
250 *
|
[4]
|
plain Danish pastry
|
|
flour from naked var
|
424
|
[21][12]
|
|
574
|
[23][11]
|
pearled grain
|
274
|
[21][12]
|
Oats
|
|
|
raw grain
|
280
|
[18][10]
|
|
388
|
[21] |
[24][14]
|
flour
|
404–688
|
[23][11]
|
|
53 *
|
[4]
|
bran
|
200 *
|
[24][14]
|
|
|
380 *
|
[24][14] |
190
|
[11][13]
|
Maize
|
|
|
|
raw grain
|
107–304
|
[23][11]
|
|
175
|
[21][12]
|
|
|
579
|
[19][15]81 * |
|
wholegrain meal
|
120 *
|
[24][14]
|
degermed meal
|
4 *
|
[24][14]
|
semolina
|
3–22
|
[11][13]
|
refined corn grits
|
37
|
[11][13]
|
flour, enriched
|
20 *
|
[24][14]
|
refined flour
|
2.1 *
|
[4]
|
| [ | 24 |
bran
|
184
|
[21][12]
|
|
104
|
[23][11]
|
|
wheat tortilla
|
311
|
[11][13]
|
|
Pasta
|
|
|
wholegrain wheat pasta
|
710–1286
|
[11][13]][14] |
|
46 *
|
[24][14]
|
flakes
|
103–120
|
[23][11]
|
|
7–9
|
[11][13]
|
|
n.d.
|
[21][12]
|
starch
|
n.d.
|
[21][12]
|
popped
|
19
|
[11][13]
|
| |
|
|
375
|
[19][15]
|
pasta, not specified
|
480–1350
|
[12]
|
raw grain from naked var.
|
|
n.d.
|
[21][12]
|
Rice
|
|
|
grain
|
1–5
|
[11][13]
|
|
n.d.
|
[21][12]
|
refined flour
|
8.4 *
|
[4]
|
expanded
|
n.d.
|
[21][12]
|
starch
|
n.d.
|
[21][12]
|
Amaranth (Amaranthus cruentus)
|
|
|
| [ | 2]
|
refined wheat pasta
|
628–706
|
[11][ |
|
440
|
[18][10]
|
wholegrain flour
|
raw grain
|
7420
|
[23][11]
|
13 | ] |
|
|
680 *
|
[24][14]
|
|
646
|
[11][13]
|
expanded grain
|
669
|
[23][11]
|
|
607
|
[21][12]
|
flour
|
895–1225
|
[23][11]
|
|
871
|
[21][12]
|
sample type not specified
|
|
refined wheat (T. aestivum) pasta, uncooked
| 310 *
|
| 95–112
|
[11][13]
|
dehulled grain
|
281
|
[23][11]
|
| 253
| Proso millet
|
refined flour
|
1320 *
|
[4]
|
Buckwheat
|
|
|
wholegrain flour
|
108
|
[23][11]
|
|
7–20
|
[11][13]
|
refined flour
|
n.d.
|
[21][12]
|
groats, roasted
|
10 *
|
[4]
|
|
26 *
|
[24][14]
|
Sorghum
|
|
|
refined flour
|
425 *
|
[4]
|
Quinoa
|
|
|
grains
|
6300 *
|
[24][14]
|
3042–4428
|
[11][13]
|
610.8 *
|
[4]
|
n.d. not detected; * result expressed on wet weight.
3. Betaine Content in Cereal-Based Products
The betaine content in cereal products depends on the processing method. Two to four times lower betaine content were found in refined grain products compared to equivalent whole grain products
[11][13]. Betaine content is notably dependent on the loss of bran fraction during processing. The higher the abrasion of aleurone layer, the lower the betaine content in the product. Outstanding betaine levels were determined in wheat bran, up to 7200 µg/g (
Table 1). Likes et al.
[25][16] analyzed the betaine contents in different milling streams and reported the lowest betaine level in the cleanest milling fractions. In the study of de Zwart et al.
[2], a wide range of different foods was analyzed for betaine content and flour was denoted as an item high in betaine (730 µg/g), however it was not specified the type of flour, except that it was available from retail markets. Betaine ranges in bread, pasta, breakfast cereals and snacks are given in
Table 2. As it can be seen, the variation within each product category is high due to versatility of ingredients in product formulations. In each product category, the highest betaine content was reported for wholegrain products or products containing bran or germ. Among breads, rye, spelt, and wholemeal breads were abundant in betaine. Moderate to high betaine contents were reported for pasta products, but it must be noted that mainly uncooked samples were analyzed (
Table 2). Breakfast cereals are a mixture of cereal and non-cereal ingredients and the betaine content will depend on the contribution of each ingredient. In the study of Filipčev et al.
[23][11], two samples of commercially available breakfast cereals were analyzed, one of which contained no detectable levels of betaine whereas the other had 471 µg/g (on dry solids). A similar concluded was made by Ross et al.
[11][13] for muesli and muesli bars which were found to contain only low-to-moderate betaine levels. These products were mainly based on oats and contained other low-betaine ingredients such as dried fruits. In contrast to Ross et al.
[11][13], the USDA data
[24][14] report on much wider span of betaine in breakfast cereals, from 7 µg/greaching to as much as 3600 µg/g (on wet weight) betaine.
Table 2. Betaine content in various grain-based products.
Product
|
Betaine Content
|
References
|
* Result expressed on wet weight.
4. Betaine Content in Gluten-Free Cereal Products
Gluten-free products have been generally recognized to be low in betaine content
[11,19][13][15]. In the majority of commercially available gluten-free products, a very low level of betaine (<50 μg/g) was observed
[11][13].
Table 3 lists the betaine levels reported for commercial gluten-free products from several studies. In the bread and biscuits category, betaine levels ranged from non-detectable to 107 µg/g. Similar findings were reported by Kojić et al.
[21][12], who also found that gluten-free samples (starch, corn extrudates, pasta, cornflakes, and rice) contained no detectable levels of betaine. Gluten-free cereals contained much lower amounts of betaine in comparison to glutenous cereals: corn had 107–304 µg/g betaine
[23][11]; teff and millet between 50–150 µg/g
[11][13
n.d. not detected.
5. Stability of Betaine in Grain-Based Products
Betaine is known to be a thermostable compound that survives the severe treatment during sugar beet processing (extracting with water, treatment with CaOH
2 and CO
2, concentration, crystallization) and almost quantitatively accumulates in molasses
[29][17]. Pure anhydrous betaine decomposes at > 245 °C. Since food processing practices do not employ such high temperatures, betaine losses caused by food thermal treatments were initially not expected
[30][18]. However, some data suggest that certain cooking and baking losses of betaine may exist in spite of its thermostability in the pure form. Being a water-soluble compound with a small molecule, it is not unlikely that some betaine losses will occur, depending on the type of food processing and cooking. Available data suggest that losses are very high if processing involves water
removal after cooking or boiling due to its solubility in water. Very high losses were observed
during the baking of betaine-enriched bread, implying that fermentation by baker’s yeast may be one of
the causes but future research is needed to understand the possible mechanisms.