Anti-Nutrient

Molecule:

Oxalates

Foods:

Grains bran, nuts, soy, spinach, rhubarb, swisschard, chocolate, black tea, some fruits and vegetables. Metabolite of fungus and dysbiotic flora. Metabolism of the amino acids glycine and serine, vitamin C and sugar.
Oxalates

How to Neutralize:

Partially by cooking.

Negative Effects:

Binding with calcium: Calcium and magnesium deficiency, kidney stones, disturb digestive enzymes. Hyperoxaluria may play a significant role in autism, COPD/asthma, thyroid disease, fibromyalgia, interstitial cystitis, vulvodynia, depression, arthritis. Researchers believed that "Oxalate hyperabsorptionmay be the main reason for stone formation in more than half of the idiopathic calcium oxalate stone formers".

Oxalates affects calcium and magnesium metabolism and react with proteins to form complexes which have an inhibitory effect in peptic digestion. Ruminants, however unlike monogastric animals can ingest considerable amounts of high-oxalate plants without adverse effects, due principally to microbial decomposition in the rumen (Oke, 1969). The hulls of sesame seeds contain oxalates and it is essential that meals should be completely decorticated in order to avoid toxicities (McDonald et al., 1995). Chemical analysis carried by Alabi et al. (2005) on locust bean seeds revealed that the testa of locust bean seeds had the highest concentration of oxalate (4.96 mg/100 g) followed by the pulp (3.40 mg/100 g) and the cotyledon (1.15 mg/100 g). Olomu (1995) reported that pigeon pea contains about 0.38% oxalic acid. Oxalic acid binds calcium and forms calcium oxalate which is insoluble. Calcium oxalate adversely affects the absorption and utilization of calcium in the animal body (Olomu, 1995).

Food Name
Food Group
Protein (g)
Fat (g)
Carbohydrates (g)
Calories
Starch (g)
SucroseG
Glucose (g)
Fructose (g)
Lactose (g)
Maltose (g)
Alcohol (g)
Water (g)
Caffeine (mg)
Theobromine (mg)
Sugar (g)
Fiber (g)
Calcium (mg)
Iron (mg)
Magnesium (mg)
Phosphorus (mg)
Potassium (mg)
Sodium (mg)
Zinc (mg)
Copper (mg)
Flouride (mcg)
Manganese (mg)
Selenium(mcg)
Vitamin A(IU)
Retinol (mcg)
Beta Carotene (mcg)
Alpha Carotene (mcg)
Vitamin E (mg)
Vitamin D (mcg)
Lutein and Zeaxanthin
Vitamin C (mg)
Thiamin (B1) (mg)
Riboflavin (B2)(mg)
Niacin(B3)(mg)
Vitamin B5(mg)
Vitamin B6 (mg)
Folate (B9) (mg)
Choline (mg)
Cholesterol (mg)
Saturated Fat (g)
Net Carbs
Quinoa, uncooked
Cereal Grains and Pasta
14.12
6.07
64.16
368
52.22
NULL
NULL
NULL
NULL
NULL
NULL
13.28
NULL
NULL
NULL
7
47
4.57
197
457
563
5
3.1
0.59
NULL
2.033
8.5
14
0
8
0
2.44
0
163
NULL
0.36
0.318
1.52
0.772
0.487
184
70.2
0
0.706
57.16
Oats
Cereal Grains and Pasta
16.89
6.9
66.27
389
NULL
NULL
NULL
NULL
NULL
NULL
0
8.22
NULL
NULL
NULL
10.6
54
4.72
177
523
429
2
3.97
0.626
NULL
4.916
NULL
0
0
NULL
NULL
NULL
0
NULL
0
0.763
0.139
0.961
1.349
0.119
56
NULL
0
1.217
55.67
Wheat bran, crude
Cereal Grains and Pasta
15.55
4.25
64.51
216
NULL
NULL
NULL
NULL
NULL
NULL
0
9.89
0
0
0.41
42.8
73
10.57
611
1013
1182
2
7.27
0.998
NULL
11.5
77.6
9
0
6
0
1.49
0
240
0
0.523
0.577
13.578
2.181
1.303
79
74.4
0
0.63
21.71
Amaranth grain, uncooked
Cereal Grains and Pasta
13.56
7.02
65.25
371
57.27
1.4
0.27
0.01
0
0.01
0
11.29
NULL
NULL
1.69
6.7
159
7.61
248
557
508
4
2.87
0.525
NULL
3.333
18.7
2
0
1
0
1.19
0
28
4.2
0.116
0.2
0.923
1.457
0.591
82
69.8
0
1.459
58.55
Baking chocolate, MARS SNACKFOOD US, M&M's Semisweet Chocolate Mini Baking Bits
Sweets
4.44
26.15
65.96
517
NULL
NULL
NULL
NULL
NULL
NULL
NULL
1.27
NULL
NULL
53.07
6.7
34
2.91
NULL
NULL
NULL
2
NULL
NULL
NULL
NULL
NULL
74
NULL
NULL
NULL
NULL
NULL
NULL
0
NULL
NULL
NULL
NULL
NULL
NULL
NULL
3
15.618
59.26
Bread, wheat bran
Baked Products
8.8
3.4
47.8
248
NULL
NULL
NULL
NULL
NULL
NULL
0
37.8
0
0
9.68
4
74
3.07
81
185
227
486
1.35
0.221
NULL
1.668
31
0
0
0
0
0.32
0
54
0
0.397
0.287
4.402
0.536
0.176
105
18.7
0
0.779
43.8
Soybeans, mature seeds, cooked, boiled, with salt
Legumes and Legume Products
18.21
8.97
8.36
172
NULL
NULL
NULL
NULL
NULL
NULL
NULL
62.55
NULL
NULL
2.36
6
102
5.14
86
245
515
237
1.15
0.407
NULL
0.824
7.3
9
0
5
0
0.35
0
0
1.7
0.155
0.285
0.399
0.179
0.234
54
NULL
0
1.297
2.36
Peanuts, all types, raw
Legumes and Legume Products
25.8
49.24
16.13
567
NULL
NULL
NULL
NULL
NULL
NULL
0
6.5
0
0
4.72
8.5
92
4.58
168
376
705
18
3.27
1.144
NULL
1.934
7.2
0
0
0
0
8.33
0
0
0
0.64
0.135
12.066
1.767
0.348
240
52.5
0
6.279
7.63
Nuts, macadamia nuts, raw
Nut and Seed Products
7.91
75.77
13.82
718
1.05
4.43
0.07
0.07
0
0
0
1.36
0
0
4.57
8.6
85
3.69
130
188
368
5
1.3
0.756
NULL
4.131
3.6
0
0
NULL
NULL
0.54
0
NULL
1.2
1.195
0.162
2.473
0.758
0.275
11
NULL
0
12.061
5.22
Seeds, sesame seeds, whole, dried
Nut and Seed Products
17.73
49.67
23.45
573
NULL
NULL
NULL
NULL
NULL
NULL
0
4.69
0
0
0.3
11.8
975
14.55
351
629
468
11
7.75
4.082
NULL
2.46
34.4
9
0
5
0
0.25
0
0
0
0.791
0.247
4.515
0.05
0.79
97
25.6
0
6.957
11.65
Nuts, almonds
Nut and Seed Products
21.15
49.93
21.55
579
0.72
3.95
0.17
0.11
0
0.04
0
4.41
0
0
4.35
12.5
269
3.71
270
481
733
1
3.12
1.031
NULL
2.179
4.1
2
0
1
0
25.63
0
1
0
0.205
1.138
3.618
0.471
0.137
44
52.1
0
3.802
9.05
Nuts, brazilnuts, dried, unblanched
Nut and Seed Products
14.32
67.1
11.74
659
0.25
2.33
0
0
0
0
0
3.42
0
0
2.33
7.5
160
2.43
376
725
659
3
4.06
1.743
NULL
1.223
1917
0
0
0
0
5.65
0
0
0.7
0.617
0.035
0.295
0.184
0.101
22
28.8
0
16.134
4.24
Nuts, cashew nuts, raw
Nut and Seed Products
18.22
43.85
30.19
553
23.49
5.81
0.05
0.05
0
0
NULL
5.2
NULL
NULL
5.91
3.3
37
6.68
292
593
660
12
5.78
2.195
NULL
1.655
19.9
0
0
0
0
0.9
0
22
0.5
0.423
0.058
1.062
0.864
0.417
25
NULL
0
7.783
26.89
Carrots, baby, raw
Vegetables and Vegetable Products
0.64
0.13
8.24
35
0
2.72
1.04
1
0
0
NULL
90.35
NULL
NULL
4.76
2.9
32
0.89
10
28
237
78
0.17
0.1
NULL
0.151
0.9
13790
0
6391
3767
NULL
0
358
2.6
0.03
0.036
0.556
0.401
0.105
27
7.5
0
0.023
5.34
Spinach, cooked, boiled, drained, with salt
Vegetables and Vegetable Products
2.97
0.26
3.75
23
NULL
NULL
NULL
NULL
NULL
NULL
0
91.21
0
0
0.43
2.4
136
3.57
87
56
466
306
0.76
0.174
37.8
0.935
1.5
10481
0
6288
0
2.08
0
11308
9.8
0.095
0.236
0.49
0.145
0.242
146
19.7
0
0.043
1.35
Sweet potato, cooked, baked in skin, flesh, with salt
Vegetables and Vegetable Products
2.01
0.15
20.71
92
7.05
2.28
0.57
0.5
0
3.12
0
75.78
0
0
6.48
3.3
38
0.69
27
54
475
246
0.32
0.161
NULL
0.497
0.2
NULL
0
NULL
NULL
0.71
0
NULL
19.6
0.107
0.106
1.487
0.884
0.286
6
13.1
0
0.052
17.41
Taro, cooked, with salt
Vegetables and Vegetable Products
0.52
0.11
34.6
142
NULL
NULL
NULL
NULL
NULL
NULL
0
63.8
0
0
0.49
5.1
18
0.72
30
76
484
251
0.27
0.201
NULL
0.449
0.9
84
0
39
0
2.93
0
0
5
0.107
0.028
0.51
0.336
0.331
19
21.3
0
0.023
29.5
Beets, cooked, boiled. drained, with salt
Vegetables and Vegetable Products
1.68
0.18
9.96
44
NULL
NULL
NULL
NULL
NULL
NULL
NULL
87.06
NULL
NULL
7.96
2
16
0.79
23
38
305
285
0.35
0.074
NULL
0.326
0.7
35
0
21
0
0.04
0
0
3.6
0.027
0.04
0.331
0.145
0.067
80
6.3
0
0.028
7.96
Spinach, raw
Vegetables and Vegetable Products
2.86
0.39
3.63
23
NULL
0.07
0.11
0.15
0
0
0
91.4
0
0
0.42
2.2
99
2.71
79
49
558
79
0.53
0.13
NULL
0.897
1
9377
0
5626
0
2.03
0
12198
28.1
0.078
0.189
0.724
0.065
0.195
194
19.3
0
0.063
1.43
Chard, swiss, raw
Vegetables and Vegetable Products
1.8
0.2
3.74
19
NULL
NULL
NULL
NULL
NULL
NULL
0
92.66
0
0
1.1
1.6
51
1.8
81
46
379
213
0.36
0.179
NULL
0.366
0.9
6116
0
3647
45
1.89
0
11000
30
0.04
0.09
0.4
0.172
0.099
14
18
0
0.03
2.14
Rhubarb, raw
Fruits and Fruit Juices
0.9
0.2
4.54
21
NULL
NULL
NULL
NULL
NULL
NULL
0
93.61
0
0
1.1
1.8
86
0.22
12
14
288
4
0.1
0.021
NULL
0.196
1.1
102
0
61
0
0.27
0
170
8
0.02
0.03
0.3
0.085
0.024
7
6.1
0
0.053
2.74
Plantains, raw
Fruits and Fruit Juices
1.3
0.37
31.89
122
NULL
NULL
NULL
NULL
NULL
NULL
0
65.28
0
0
15
2.3
3
0.6
37
34
499
4
0.14
0.081
NULL
NULL
1.5
1127
0
457
438
0.14
0
30
18.4
0.052
0.054
0.686
0.26
0.299
22
13.5
0
0.143
29.59
Spices, cinnamon, ground
Spices and Herbs
3.99
1.24
80.59
247
NULL
0.02
1.04
1.11
0
0
0
10.58
0
0
2.17
53.1
1002
8.32
60
64
431
10
1.83
0.339
NULL
17.466
3.1
295
0
112
1
2.32
0
222
3.8
0.022
0.041
1.332
0.358
0.158
6
11
0
0.345
27.49
Spices, cumin seed
Spices and Herbs
17.81
22.27
44.24
375
NULL
NULL
NULL
NULL
NULL
NULL
0
8.06
0
0
2.25
10.5
931
66.36
366
499
1788
168
4.8
0.867
NULL
3.333
5.2
1270
0
762
0
3.33
0
448
7.7
0.628
0.327
4.579
NULL
0.435
10
24.7
0
1.535
33.74
Spices, curry powder
Spices and Herbs
14.29
14.01
55.83
325
NULL
0.62
1.14
0.79
0
0
0
8.8
0
0
2.76
53.2
525
19.1
255
367
1170
52
4.7
1.2
NULL
8.3
40.3
19
0
11
0
25.24
0
0
0.7
0.176
0.2
3.26
1.07
0.105
56
64.2
0
1.648
2.63
Spices, onion powder
Spices and Herbs
10.41
1.04
79.12
341
NULL
3.87
0.73
1.67
0
0
0
5.39
0
0
6.63
15.2
384
3.9
113
322
985
73
4.05
0.59
NULL
1.3
14.3
0
0
0
0
0.27
0
0
23.4
0.457
0.08
0.321
0.732
0.718
64
39
0
0.219
63.92
Spices, parsley, dried
Spices and Herbs
26.63
5.48
50.64
292
NULL
4.09
2.76
0.42
0
0
0
5.89
0
0
7.27
26.7
1140
22.04
400
436
2683
452
5.44
0.78
NULL
9.81
14.1
1939
0
1152
17
8.96
0
2428
125
0.196
2.383
9.943
1.062
0.9
180
97.1
0
1.378
23.94
Spices, pepper, black
Spices and Herbs
10.39
3.26
63.95
251
NULL
0.02
0.24
0.23
0
0
0
12.46
0
0
0.64
25.3
443
9.71
171
158
1329
20
1.19
1.33
34.2
12.753
4.9
547
0
310
12
1.04
0
454
0
0.108
0.18
1.143
1.399
0.291
17
11.3
0
1.392
38.65
Spices, poppy seed
Spices and Herbs
17.99
41.56
28.13
525
NULL
2.33
0.37
0.29
0
0
0
5.95
0
0
2.99
19.5
1438
9.76
347
870
719
26
7.9
1.627
NULL
6.707
13.5
0
0
0
0
1.77
0
0
1
0.854
0.1
0.896
0.324
0.247
82
8.8
0
4.517
8.63
Spices, turmeric, ground
Spices and Herbs
9.68
3.25
67.14
312
NULL
2.38
0.38
0.45
0
0
0
12.85
0
0
3.21
22.7
168
55
208
299
2080
27
4.5
1.3
NULL
19.8
6.2
0
0
0
0
4.43
0
0
0.7
0.058
0.15
1.35
0.542
0.107
20
49.2
0
1.838
44.44
Spices, caraway seed
Spices and Herbs
19.77
14.59
49.9
333
NULL
NULL
NULL
NULL
NULL
NULL
0
9.87
0
0
0.64
38
689
16.23
258
568
1351
17
5.5
0.91
NULL
1.3
12.1
363
0
206
8
2.5
0
454
21
0.383
0.379
3.606
NULL
0.36
10
24.7
0
0.62
11.9

3.1. Definition 


Oxalate, or oxalic acid, is a substance that can form insoluble salts with minerals, including sodium, potassium, calcium, iron, and magnesium. These compounds are produced in small amounts in both plants, and mammals. All major groups of photosynthetic organisms produce oxalate. It is suggested that plants manufacture oxalate for a variety of functions including calcium regulation, plant protection, and detoxification of heavy metals [51]. In mammals, endogenous oxalate is a metabolite of ascorbate, glyoxylate, hydroxyproline and glycine. Urinary oxalate mostly consists of endogenous oxalate, as opposed to exogenous dietary oxalate. Plant-derived oxalate is available in several different forms; as either water-soluble oxalate (oxalic acid, potassium, sodium and ammonium oxalates) or insoluble oxalate salts (primarily as calcium oxalate) [52]. Soluble (unbound) oxalates can chelate minerals, reducing absorption, or are absorbed through the intestines and colon. Absorbed dietary oxalates are believed to contribute to calcium oxalate kidney stone formation [53]. Insoluble oxalates, on the other hand, are excreted in the feces [54]. Due to their effects on nutrient absorption and possible role in kidney stone formation, oxalates are considered by some to be ‘antinutrients’. Although events of toxicity have occurred in livestock chiefly grazing on oxalate-rich plants [51], a balanced human diet typically contains only small amounts of oxalates [53]. 


3.2. Background 


Oxalates are present in many commonly consumed plant foods. Plant foods with the highest oxalate content include spinach, swiss chard, amaranth, taro, sweet potatoes, beets, rhubarb, and sorrel. Raw legumes, whole grains, nuts, baking cocoa and tea also contain oxalate, though in smaller amounts. Distribution of oxalate within a plant can vary. Leaves (spinach, beet greens) are reported to have far greater oxalate content than stalks (rhubarb) or roots (beets, carrots). A distinction should be made between total oxalate, soluble and insoluble oxalate, as excess soluble oxalate has more of an effect on bioavailability and kidney stone formation [54]. Chai and Liebman reported fresh spinach to contain an average of 1145 mg/100 g fresh weight (FW) total oxalate, 803 mg being in the soluble form, and 343 mg being insoluble oxalate [54]. Another group found spinach to contain 978 mg/100 g FW of total oxalate, 543 mg of that being soluble oxalate [55]. Nuts are also reported to be rich in oxalates, ranging from 42 mg/100 g in raw macadamia nuts, to 140, 262, and 469 mg/100 g in roasted peanuts, cashews and almonds, respectively. Soluble content in peanuts and almonds were found to be 108 mg and 153 mg/100 g [56]. Wheat bran contains a somewhat higher amount of soluble oxalate (113 mg/100 g dry weight (DW)), while whole grain products contain much less (13.8 mg in oats, 44 mg/100 g in whole wheat flour) [57]. Rawlegumes vary widelyin oxalate content. Soybeans contain the greatest amount (370 mg/100 g DW), followed by lentils and peas (168–293 mg/100 g DW), chickpeas (192 mg/100 g DW), and common beans (98–117 mg/100 g DW) [19]. Soluble oxalate in raw chickpeas and lentils is only a fraction of total oxalate [58]. Beet root, another vegetable known for its oxalate content, averages 65 mg/100 g FW of oxalate, with 47 mg being soluble oxalate [54,55]. Differences in total oxalate content is variable among cultivars, season, and growing conditions. For example, among 310 different cultivars of spinach, oxalate concentration ranged from 647.2 to 1286.9 mg/100 g FW, with an average of 984 mg/100 g [59]. Savage et al., on the other hand, found only 266.2 mg/100 g FW in New Zealand grown spinach [53]. Horner and colleagues found over a two-fold difference in oxalate values among 116 cultivars of soy, ranging from 82 to 285 mg/100 g dry weight [60]. Time of harvest can have additional impacts on oxalate concentrations [61]. Research has not demonstrated any differences in oxalate between organic and conventional cultivars [62]. Oxalate values in raw food items are not representative of actual content consumed, as items like legumes and greens are typically cooked prior to consumption. Traditional preparation methods have demonstrated efficacy in significantly reducing oxalate content. 


3.3. Effects of Cooking/Processing 


Like lectins, the cooking, preparation, and processing of food can impact the oxalate content and, therefore, mineral availability of food items (Table 2). Due to oxalate’s solubility in water, wet processing methods such as boiling, and steaming seem to be the most efficient solutions to decreasing oxalate content. Chai and Liebman reported significant reductions of soluble oxalate in vegetables by boiling for 12 min, ranging from 30 to 87% [54]. Spinach and Swiss chard experienced the largest losses (87 and 85%, respectively). Steaming has a lesser impact, though still resulted in losses of 46% and 42% in green Swiss chard and spinach, respectively [54]. Vegetables with lesser exposed surface area and relatively small amounts of oxalate, such as beets, carrots and Brussels sprouts, did not experience similar reductions in soluble oxalate [54]. These results are in agreement with a previous analysis on New Zealand vegetables [53]. Traditional and industrial cooking methods such as soaking overnight and boiling or autoclaving, significantly reduces total and soluble oxalate content in legumes. Cooking lentils on a hot plate for just fifteen minutes reduced soluble oxalate content by 42.6%, and in chickpeas (60 min) by 19.5% [58]. Common beans (cooked for 45 min) experienced a 59.61% loss in oxalate. Even further reductions of 85.7–92.9% were observed in canning (autoclaving) and microwaving of legumes [58]. It has also been found that an overnight soak, followed by a 2-h boil reduced soluble oxalate in red beans by 40.5% [58]. In contrast, there was a 76.9% loss of soluble oxalate in white beans [55]. These differences may be due to variations in genetics, growing conditions, cooking times and exact cooking temperatures. Roasting of peanuts, cashews and almonds did not have any significant impact on oxalate content [56]. In most cases, cooking techniques significantly reduces soluble oxalate, and should therefore enhance mineral availability. Aside from cooking, pairing high-oxalate foods with calcium-rich foods may offset soluble oxalate absorption. A normal calcium diet (800–1,000 mg/day) should be able to offset potential inhibitory effects from dietary oxalates [63]. 


3.4. Safety 


Despite evidence of relatively low soluble oxalate concentration in most ‘problematic foods’, dietary oxalate is thought to play a role in hyperoxaluria, a risk factor in the formation of calcium oxalate kidney stones (Table 1). Total dietary oxalate intake is only in the range of 50–200 mg, though in some individuals could be as high as 1000 mg [64]. It has been suggested that dietary oxalate may contribute up to 50% of total urinary oxalate excretion, and that one-third of stone formers hyper-absorb oxalate at a rate of more than 10% total oxalate consumed [65]. 


3.5. Human Studies 


A study of 20 healthy men and women found that an oxalate-rich diet (600 mg/day from rhubarb juice) significantly increased urinary excretion from 0.354 to 0.542 mmol/24 h [64]. However, oxalate is not typically consumed every day in such a concentrated form as rhubarb juice, but is, instead, a small fragment in an intricate web of dietary factors. Observing dietary patterns, a prospective analysis from the Nurses’ Health Study (NHS) found only a modest association between dietary oxalate and kidney stone formation after multivariate adjustment [66]. Participants in the highest quintile as compared to the lowest quintile of dietary oxalate, experienced a relative risk of 1.22 for men and 1.21 for older women. Even more significant, in men with lower calcium intake (<755 mg/day), the risk in the highest quintile of dietary oxalate jumped to 1.46. Conversely, in men with calcium intake at or above the median, the multivariate risk dropped to 0.83. Overall, authors concluded that dietary oxalate is not a major risk factor for stone formation [66]. In a more recent NHS I and NHS II analysis, authors again concluded that dietary oxalate had little impact on kidney stone formation, while dietary calcium intake was inversely associated with kidney stone formation [67]. Additionally, dietary potassium, magnesium, and phytate all decrease kidney stone formation through an array of mechanisms [68]. Despite significantly more dietary oxalates (254 mg/day) and oxalate-containing foods such as nuts, vegetables, and whole grains, participants with higher DASH scores have a 40–50% decreased risk of kidney stones [68]. This is perhaps attributed to the protective and synergistic effects of phytate, potassium, calcium, and other phytochemicals all abundant in the DASH dietary pattern. Similar findings regarding the protective role of vegetables on urolithiasis risk were reported by Zhuo et al. [69]. While animal protein consumption was associated with higher kidney stone risk, vegetable and tea consumption were associated with a decreased risk of stone formation. Tea is a rich source of oxalate, yet it is believed that polyphenols and other antioxidant phytochemicals may contribute to the prevention of stone formation [69]. Although there is a connection between calcium oxalate excretion, exogenous (dietary) oxalate, and stone risk, the association may be more complex than once believed. Gastrointestinal health may also play a role in oxalate absorption and associated health risks. Those with digestive disorders such as inflammatory bowel disease (IBD) have been shown to be at higher risk for calcium-oxalate kidney stones, assumed to be partially caused by oxalate hyperabsorption [70]. Patients with bowel disorders often experience deranged intestinal barrier function, characterized by increased intestinal permeability [70]. Fat malabsorption, secondary to epithelial damage, may also contribute to excess calcium-fatty acid salts, in turn increasing the availability of soluble oxalate [71]. The combination of these factors is theorized to increase oxalate absorption, however, the association between intestinal permeability and oxalate hyperabsorption has yet to be proven. Interestingly, children with autism have demonstrated increased plasma and urinary oxalate levels, but not increased risks of kidney stone formation [72]. This result may be partially explained by increased intestinal permeability and additional dysbiosis found in those with autism spectrum disorders, though is yet to be completely elucidated [73,74]. The gut microbiome, or oxalobiome, may also play a role in reducing dietary oxalates, as bacterial species like Oxalobacter formigenes possess oxalate-degrading genes [75]. Nonetheless, human trials using oxalate-degrading probiotics have been mixed, and for the most part, unsuccessful [76,77]. 


3.6. Conclusions 


Despite the demonization of oxalate and promotion of a low-oxalate diet in kidney stone patients, more recent observational studies of dietary patterns may prompt a reevaluation of current guidelines. Certain segments of the population do seem to be at greater risk of increased oxalate excretion, and consuming oxalate-rich foods may play a possible role in kidney stone formation, but other factors such as food preparation techniques, calcium intake, endogenous oxalate production, and intestinal health may play a larger role than once thought. Cooking oxalate-rich foods, as well as consuming adequate amounts of calcium and potassium demonstrate efficiency in significantly minimizing available soluble oxalate from dietary sources. Furthermore, oxalate containing foods possess an array of protective, beneficial compounds which may outweigh any possible negative effects of oxalate.