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CAC Score (Coronary Calcium): Nutrition and Fasting Impact

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At a glance

  • Test / CT scan that scores calcified coronary plaque [1]
  • Fasting before scan / Effect on the score not established [1]
  • Diet and CAC progression / Diet studies used non-CAC endpoints [2][3]
  • Calcium supplements / Heart attack signal debated, not a CAC endpoint [4][5]
  • CAC 101 to 300 / Coronary event risk 7.73 times the risk at zero in MESA [1]
  • CAC above 300 / Coronary event risk 9.67 times the risk at zero in MESA [1]

What a CAC score measures

A CAC score comes from a CT scan of the coronary arteries and grades calcified plaque. In MESA, 6,722 adults without clinical cardiovascular disease were followed for a median of 3.8 years. There were 162 coronary events, 89 major. Compared with a score of zero, adjusted coronary event risk was 7.73 times higher for scores of 101 to 300 and 9.67 times higher above 300 [1]. Each doubling was linked to 15% to 35% higher major-event risk and 18% to 39% higher risk of any coronary event [1].

Does fasting before the scan matter?

A CAC scan measures calcified plaque in the coronary arteries on CT [1]. Whether a fast or a meal changes a same-day Agatston score has not been established.

Can diet change CAC over time?

The diet studies cited here used other endpoints. The CALERIE trial assigned 218 non-obese adults to 25% calorie restriction or an ad libitum diet for 2 years; the restriction group cut intake by 11.9% and lost 7.5 kg, with improved LDL cholesterol and blood pressure [2]. The EPIC cohort followed 448,568 adults; each 50 g/day increment in processed meat was associated with an all-cause mortality hazard ratio of 1.18 (95% CI 1.11 to 1.25) after correction for measurement error [3]. The TREAT trial randomized 116 adults with overweight or obesity to 16:8 time-restricted eating or three structured meals for 12 weeks; between-group weight change was not significant (-0.26 kg, 95% CI -1.30 to 0.78; P=.63) [6]. None of these reported a change in CAC.

Do calcium supplements affect coronary calcium?

A CAC score counts calcium in plaque; it does not measure calcium intake. The supplement heart-risk question comes from analyses of trials that tracked heart attacks and strokes. In a 2010 meta-analysis of 15 placebo-controlled trials, the 5 with patient-level data included 8,151 participants followed a median of 3.6 years. Myocardial infarction occurred in 143 on calcium and 111 on placebo (HR 1.31, 95% CI 1.02 to 1.67); stroke and death were not significant [4]. A 2011 WHI reanalysis found cardiovascular event hazard ratios of 1.13 to 1.22 with calcium plus vitamin D in 16,718 women not taking personal calcium supplements, with no change in those who were [5]. These were secondary analyses of trials not designed for cardiovascular outcomes, and the question is unsettled. In the WHI trial itself, 36,282 postmenopausal women took 1,000 mg calcium as carbonate plus 400 IU vitamin D3 daily for 7 years, and kidney stones rose (HR 1.17, 95% CI 1.02 to 1.34) [7].

Frequently asked questions

Does fasting change a CAC score?
CAC measures calcified coronary plaque on CT [1]. Whether fasting or meal timing changes the score has not been established.
Can diet lower an existing CAC score?
The diet studies cited here measured weight, blood pressure, lipids and mortality, not CAC change. CALERIE found improved LDL cholesterol and blood pressure with 25% calorie restriction over 2 years, but its endpoints were cardiometabolic risk factors [2].
Do calcium supplements raise coronary calcium?
Calcium supplement analyses tracked heart attacks and strokes, not CAC. In the 2010 meta-analysis with patient-level data, myocardial infarction occurred in 143 on calcium versus 111 on placebo, HR 1.31 (95% CI 1.02 to 1.67) [4].

References

  1. Detrano R, Guerci AD, Carr JJ, Bild DE, Burke G, Folsom AR, et al. Coronary calcium as a predictor of coronary events in four racial or ethnic groups. N Engl J Med. 2008;358(13):1336-45. Coronary calcium as a predictor of coronary events in four racial or ethnic groups
  2. Kraus WE, Bhapkar M, Huffman KM, Pieper CF, Krupa Das S, Redman LM, et al. 2 years of calorie restriction and cardiometabolic risk (CALERIE): exploratory outcomes of a multicentre, phase 2, randomised controlled trial. Lancet Diabetes Endocrinol. 2019;7(9):673-683. 2 years of calorie restriction and cardiometabolic risk (CALERIE): exploratory outcomes of a multicentre, phase 2, randomised controlled trial
  3. Rohrmann S, Overvad K, Bueno-de-Mesquita HB, Jakobsen MU, Egeberg R, Tjønneland A, et al. Meat consumption and mortality--results from the European Prospective Investigation into Cancer and Nutrition. BMC Med. 2013;11:63. Meat consumption and mortality--results from the European Prospective Investigation into Cancer and Nutrition
  4. Bolland MJ, Avenell A, Baron JA, Grey A, MacLennan GS, Gamble GD, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010;341:c3691. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis
  5. Bolland MJ, Grey A, Avenell A, Gamble GD, Reid IR. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women's Health Initiative limited access dataset and meta-analysis. BMJ. 2011;342:d2040. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women's Health Initiative limited access dataset and meta-analysis
  6. Lowe DA, Wu N, Rohdin-Bibby L, Moore AH, Kelly N, Liu YE, et al. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med. 2020;180(11):1491-1499. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial
  7. Jackson RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-83. Calcium plus vitamin D supplementation and the risk of fractures
  8. Daily Value on the Nutrition and Supplement Facts Labels | FDA. Daily Value on the Nutrition and Supplement Facts Labels | FDA
Evidence overview for CAC Score (Coronary Calcium): Nutrition and Fasting Impact