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Acid-base analysis of individuals following two weight loss diets

European Journal of Clinical Nutrition volume 61, pages 1416–1422 (2007)Cite this article

Abstract

Objective:

To examine the effects of low-carbohydrate, ketogenic (LCKD) and low-fat (LFD) diets on acid-base status.

Design:

Prospective analysis of volunteers from two clinical trials.

Participants:

Subset of 39 volunteers from a randomized trial comparing the effects of an LCKD with an LFD, and a single-arm trial of an LCKD.

Setting:

Outpatient research clinic.

Intervention:

LCKD (initially <20 g of carbohydrate daily) or LFD (<30% of energy from fat, 500–1000 kcal energy reduction) instruction.

Measurements:

Arterial blood gas analysis, serum chemistries (electrolytes, urea nitrogen/creatinine, glucose, ketone bodies, lactate), anion gap, and urine ketone bodies measured at weeks 0, 2, 8, and 24.

Results:

Participants had a mean (±standard deviation) age of 43.5±9.3 years; 28 (72%) were female, 29 (74%) were Caucasian. Using linear mixed-model analysis to examine blood test changes from baseline to 24 weeks, the LFD group experienced a decrease in arterial blood pH from a mean of 7.43 at week 0 to 7.40 at week 24 (P=0.03), and the LCKD group experienced a decrease from 7.42 at week 0 to 7.40 at week 24 (P=0.01). The lowest pH measurements observed were 7.34 in the LFD group and 7.37 in the LCKD group. Although serum bicarbonate appeared to decrease from baseline at weeks 2 and 8 in the LCKD group, the change at 24 weeks was not statistically significant in either diet group, and only four of 131 (two of 92 from the LCKD group) measurements were less than 22 mmol/l. The proportion of participants with elevated urine and serum ketone body levels rose in the LCKD group only, was highest at week 2, and decreased over the subsequent time points.

Conclusion:

In individuals following an LCKD or an LFD, blood pH decreased mildly and the LCKD group experienced a small, transient decrease in serum bicarbonate in conjunction with mild ketosis. This suggests that an LCKD induced a mild compensated metabolic acidosis, but no individual showed evidence of significant metabolic derangement.

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Acknowledgements

The authors thank Keith Tomlin, Bill Bryson, and Juanita Hepburn for assistance with data collection. Dr Yancy is supported by Health Services Research Career Development Award RCD 02-183-1 from the Department of Veterans Affairs, Washington, DC, USA

Author information

Authors and Affiliations

  1. Department of Veterans' Affairs Medical Center, Center for Health Services Research in Primary Care, Durham, NC, USA

    W S Yancy Jr, M K Olsen & T Dudley

  2. Department of Medicine, Duke University Medical Center, Durham, NC, USA

    W S Yancy Jr, M K Olsen & E C Westman

  3. Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC, USA

    M K Olsen

Authors
  1. W S Yancy Jr
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  2. M K Olsen
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  3. T Dudley
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  4. E C Westman
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Corresponding author

Correspondence to W S Yancy Jr.

Additional information

Guarantor: WS Yancy Jr.

Contributors: WSY conceived, designed and coordinated the study; participated in data collection; performed statistical analysis and drafted the paper. MKO and TD performed statistical analysis. ECW conceived and designed the study, provided personnel and funding for laboratory tests and facilitated recruitment of participants. All authors assisted with interpretation of the data and contributed to the intellectual content of and approved the final paper.

Appendix

Appendix

Nutritional supplement ingredients (Atkins nutritionals, Inc.)

Multivitamin formula (administered per day in 6 capsules): Vitamin A as acetate (3000 IU), vitamin A as β-carotene w/mixed carotenoids (1200 IU), vitamin C (360 mg), vitamin D-3 (400 IU), vitamin E (300 IU), vitamin B1 (50 mg), vitamin B2 (50 mg), niacin (40 mg), vitamin B6 (50 mg), folate (1600 mg), vitamin B12 (800 mcg), vitamin K (10 mcg), biotin (600 mcg), pantothenic acid (120 mg), calcium (500 mg), magnesium (250 mg), zinc (50 mg), selenium (200 mcg), manganese (10 mg), chromium (600 mcg), molybdenum (60 mcg), potassium (20 mg), inositol hexanicotinate (100 mg), choline bitartrate (100 mg), para-amino benzoic acid (100 mg), vanadyl (80 mcg), n-acetyl-l-cysteine (120 mg), pantethine (150 mg), quercetin (100 mg), boron (2 mg), grape seed extract (40 mg), green tea (80 mg). Unspecified amounts of lecithin extracts, garlic, arginine, licorice, bromelain, pantethine, spirulina, inulin, lactoferrin, bioperine, and acidophilus.

Essential oil formula (administered per day in 3 capsules): flaxseed oil (1200 mg), borage seed oil (1200 mg), fish oil (1200 mg), vitamin E (15 IU).

Diet formula (administered per day in 6 capsules): Citrin (2700 mg), chromium (1200 mcg), soy extract (9000 mg), methionine (1500 mg), L-carnitine (3000 mg), vitamin B6 (120 mg), pantethine (120 mg), asparagus (300 mg), parsley (300 mg), kelp (120 mg), spirulina (300 mg), potassium citrate (594 mg), magnesium (360 mg), L-glutamine (450 mg), Dl-phenylalanine (900 mg), L-tyrosine (450 mg), piperine (30 mg).

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Yancy, W., Olsen, M., Dudley, T. et al. Acid-base analysis of individuals following two weight loss diets. Eur J Clin Nutr 61, 1416–1422 (2007). https://doi.org/10.1038/sj.ejcn.1602661

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