Colby cheese: the trials are on Cheddar, the numbers are on Colby

We found no study that names Colby, so the trials on this page used Cheddar, a close relative that is firmer and drier. In a randomized crossover trial in 24 healthy young adults, a portion of Cheddar with 20 g of protein did not change insulin at any point over 5 hours, while protein-matched milk spiked it at 20 minutes. Cheese also released its amino acids more slowly, peaking around 120 minutes. Over the full 5 hours the total that reached the blood matched milk. Each of these was a single test meal, so none of it says what months of eating cheese would do. What Colby itself carries comes from one USDA record with no sample spread behind it: per 3.5 oz (100 g), 20 g of saturated fat, a full Daily Value, with 685 mg of calcium and 24 g of protein. A 21 g slice works out to about 4.2 g of saturated fat and 144 mg of calcium, recalculated from the 100 g values rather than measured.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• 3.5 oz (100 g) of Colby cheese carries about 20 g of saturated fat, 685 mg of calcium and 24 g of protein, and this rests on a single USDA reference record with no sample spread behind it. — USDA SR Legacy reference record Cheese, colby (FDC 173416) Evidence E source
  Saturated fat 20.2 g (101% DV), calcium 685 mg (53% DV), protein 23.8 g (48% DV) per 3.5 oz (100 g)
• US law defines Colby as at most 40% moisture with at least 50% milkfat in the solids, and Colby made from raw milk must be aged at least 60 days at 35 F or warmer. — US standard of identity for Colby cheese, 21 CFR 133.118 Evidence E source
  Moisture <= 40%; milkfat >= 50% of solids; unpasteurised milk requires >= 60 days curing at >= 35 F

What a real portion looks like

• A typical slice of Colby weighs 21 g in US dietary survey measures, which works out to about 144 mg of calcium and 4.2 g of saturated fat. — FNDDS food Cheese, Colby (code 14104200, FDC 2705712), US household measures Evidence E source
  1 slice 21 g; 1 cracker-size slice 9 g; 1 cubic inch 17 g; 1 stick 28 g; 1 cup shredded 113 g; per 21 g slice about 144 mg calcium, 4.2 g saturated fat, 5.0 g protein (recalculated from 100 g SR Legacy values)

What your body absorbs

• In a crossover RCT in 24 young adults, 20 g of protein from Cheddar cheese released branched-chain amino acids into the blood more slowly than milk, peaking around 120 minutes and staying up longer. — 24 healthy young adults (12 men, 12 women, about 27 years, BMI about 23), cheese providing 20 g protein versus an isonitrogenous amount of milk, single test meals (n = 24) Evidence B source
  BCAA appearance slower with cheese, peak at about 120 min versus earlier with milk
• Over 5 hours the total amount of amino acids absorbed from Cheddar cheese matched milk in 24 adults: cheese changed the timing, not the total. — 24 healthy young adults (12 men, 12 women), protein-matched Cheddar cheese versus milk, blood sampled for 300 min (n = 24) Evidence B source
  Area under the curve over 5 h for total BCAA, leucine, isoleucine, valine, essential and non-essential amino acids not different between cheese and milk
• The cheese structure itself matters: in a crossover RCT in 18 men, a casein gel with the same fat and protein raised blood triglycerides by 21 mg/dL (0.24 mmol/L) more than Cheddar. — normal-weight men aged 18 to 40, 25 enrolled and 18 completed, four fat- and protein-matched dairy meals, 8 h follow-up (n = 18) Evidence B source
  Postprandial triglycerides 0.24 +/- 6.2 mg/dL (0.07 mmol/L) higher after the casein gel than after Cheddar (P <= 0.05); apoB-48 unaffected

What cooking and storage change

• Melting cheese in the oven or under a grill keeps all of its calcium but, by the USDA table, about 45% of vitamin B12 and 25% of thiamin are lost, while simple reheating loses about 5%. — USDA retention factors for the group Dairy and Egg Products, the group Colby belongs to by its own USDA record Evidence E source
  Baked or broiled cheese: calcium, phosphorus, zinc, riboflavin 100% retained; vitamin B12 55%; thiamin, vitamin B6, choline 75%; folate 80%. Reheated cheese: B vitamins 95%

What it does to your health

• In the same trial, milk spiked insulin at 20 minutes while a protein-matched portion of Cheddar did not change insulin at any time point. — 24 healthy young adults, Cheddar cheese with 20 g protein versus milk, blood sampled for 300 min (n = 24) Evidence B source
  Milk: insulin spike at 20 min, different from cheese at 20 and 40 min (p < 0.0001); cheese: no significant change from baseline
• A meta-analysis of 9 observational studies found no significant link between cheese and Parkinson disease. — meta-analysis of 9 observational studies (8 cohorts, 634,327 participants, 4285 cases) (n = 634327) Evidence C source
  No significant association for cheese; total dairy RR 1.21 (95% CI 1.07-1.37)
• A dose-response meta-analysis of 29 prospective cohorts linked each extra 10 g of cheese a day with 4% higher Parkinson disease risk. — 29 prospective cohort studies with 1,307,337 participants (n = 1307337) Evidence C source
  4% higher risk per 10 g cheese per day (linear dose-response); milk 13% per cup per day

Safety, limits and interactions

• In a small Turkish case-control study, mothers of infants with cow's milk allergy had eaten slightly less cheese in pregnancy, 210 versus 225 g a week. — 95 children aged 0 to 3 years, 46 with cow's milk protein allergy and 49 controls, maternal diet by interview (n = 95) Evidence C source
  Maternal cheese 210 g/week in cases versus 225 g/week in controls (p = 0.042); yogurt 230 versus 420 g/week
• FDA says pregnant women, older people and people with weakened immune systems should not eat unpasteurized milk products, which carry a high Listeria risk. — pregnant women, the elderly, people with weakened immune systems Evidence E source
  Advised not to eat unpasteurized milk products or any queso fresco-type cheeses (high Listeria risk)

What people believe that the data does not support

• The EU refused to let milk and cheese be marketed as promoting dental health in children. — EU Register on nutrition and health claims, claim POL-HC-6306 Evidence E source
  Status Non-authorized
• The EU also refused the claim that three portions of dairy a day help children and teenagers keep a healthy weight. — EU Register on nutrition and health claims, claim POL-HC-6305 Evidence E source
  Status Non-authorized

The bottom line

A second crossover trial looked at the structure of cheese. In 18 men aged 18 to 40, a casein gel with the same fat and protein as Cheddar raised blood triglycerides by 21 mg/dL (0.24 mmol/L) more over the following hours (standard error 0.07). Only men took part, the cheese was again Cheddar, and homogenizing it made no difference. Melting cheese in the oven or under a grill keeps all of its calcium by the USDA table, while vitamin B12 drops to 55% and thiamin to 75%. Those factors are set for cheese as a group, date from 1975 and do not name Colby. Observational data on cheese and Parkinson disease disagree. A meta-analysis of 9 studies with 634,327 people found no significant link for cheese. A dose-response meta-analysis of 29 cohorts with 1.3 million people reported 4% higher risk for every 10 g of cheese a day, and its abstract gives no confidence interval for that figure. Both are associations. When two syntheses reach different answers, the honest reading is that the question is open. The EU refused two dairy claims aimed at children: that milk and cheese promote dental health, and that three portions of dairy a day help keep a healthy weight through childhood and adolescence. A refusal means the evidence fell short when it was assessed. It does not prove the opposite. The only safety-related card we hold on Colby is a legal rule, and a legal rule is not a safety guarantee. US rules allow Colby made from unpasteurised milk only if it has been cured for at least 60 days at 35 F or warmer. We have no card on how well that curing controls germs in raw-milk cheese. FDA says pregnant women, older people and people with weakened immune systems should not eat unpasteurized milk products, which carry a high risk of Listeria, and raw-milk Colby is an unpasteurized milk product. We have no card on Colby for allergy or medicines. One small Turkish case-control study of 95 children found that mothers of infants with cow's milk allergy recalled eating slightly less cheese in pregnancy, 210 against 225 g a week. It relied on memory, the gap is 15 g, and the cheese type was not recorded, so it tells a pregnant reader nothing either way about allergy or about safety.

Sources

1. colby-r2-01 · USDA FoodData Central SR Legacy, dataset
   Cheese, colby (FDC 173416, SR Legacy, Dairy and Egg Products): saturated fat 20.218 g per 100 g = 101% DV; calcium 685 mg = 53% DV; protein 23.76 g = 48% DV; Foundation samples 0, CoFID match none
   USDA FoodData Central, SR Legacy, FDC 173416 · checked 2026-09-29
2. colby-r2-12 · US standard of identity
   It contains not more than 40 percent of moisture, and its solids contain not less than 50 percent of milkfat, as determined by the methods prescribed in § 133.5 (a), (b), and (d). ... If the milk used is not pasteurized, the cheese so made is cured at a temperature of not less than 35 °F for not less than 60 days.
   21 CFR 133.118, Colby cheese (CFR edition April 1, 2025) · checked 2026-09-29
3. colby-r2-02 · USDA FNDDS portion weights, dataset
   Cheese, Colby (FNDDS 14104200, FDC 2705712): 1 cracker-size slice 9 g; 1 slice 21 g; 1 stick 28 g; 1 cup, shredded 113 g; 1 cup, diced 132 g; 1 cubic inch 17 g; Quantity not specified 21 g
   USDA FNDDS 2021-2023, food code 14104200 (FDC 2705712) · checked 2026-09-29
4. colby-r2-04 · randomized crossover trial in humans
   We found that cheese ingestion had a slower yet more sustained branched-chain amino acid circulation appearance over the postprandial period peaking at ~120 min.
   Nutrients, 2021 · checked 2026-09-29
5. colby-r2-05 · randomized crossover trial in humans
   Despite differences in amino acid kinetics between the products, the area under the curve over 5 h for total BCAA, leucine, isoleucine, valine, total EAA, and total NEAA were not different between cheese and milk products (Figure 3A–F).
   Nutrients, 2021 · checked 2026-09-29
6. colby-r2-07 · randomized crossover trial in humans
   Postprandial triglycerides (TGs) (primary outcome) increased by (mean ± SEM) 0.24 ± 0.07 and 0.19 ± 0.07 mmol/L after MCI Gel compared with Cheese and Hom. Cheese, respectively (both P ≤ 0.05).
   Am J Clin Nutr, 2021 · checked 2026-09-29
7. colby-r2-03 · USDA Table of Nutrient Retention Factors, dataset
   USDA-RETN-R6:1 CHEESE,BAKED, group Dairy and Egg Products: vitamin_b12_ug 55% retained, thiamin_mg 75%, vitamin_b6_mg 75%, choline_mg 75%, folate_total_ug 80%, calcium_mg 100%, riboflavin_mg 100%; USDA-RETN-R6:3 CHEESE,BROILED: vitamin_b12_ug 55%, thiamin_mg 75%, calcium_mg 100%; USDA-RETN-R6:7 CHEESE,REHEATED: vitamin_b12_ug 95%, thiamin_mg 95%, folate_total_ug 95%, calcium_mg 100%
   USDA Table of Nutrient Retention Factors, Release 6, 2007, Retn_Codes 1, 3 and 7 · checked 2026-09-29
8. colby-r2-06 · randomized crossover trial in humans
   Milk induced a rapid spike in insulin 20 min after ingestion ... while cheese consumption did not significantly change insulin at any time point (Figure 2A).
   Nutrients, 2021 · checked 2026-09-29
9. colby-r2-08 · systematic review and meta-analysis of cohort and case-control studies
   No significant associations were found for yogurt/fermented milk, cheese, butter, or ice cream.
   Public Health, 2026 · checked 2026-09-29
10. colby-r2-09 · systematic review and dose-response meta-analysis of prospective cohorts
    Linear dose-response analysis showed a 5%-7% increased risk for every 100-g/day dairy and low-fat dairy intake, 4% increased risk per 10-g cheese/day, and 13% increased risk per 1 cup milk/day.
    Nutr Rev, 2026 · checked 2026-09-29
11. colby-r2-13 · case-control study in humans
    Yogurt intake during pregnancy was lower in cases (230 g/week) than in controls (420 g/week) (p = 0.011), while cheese intake was 210 g/week and 225 g/week, respectively (p = 0.042).
    Int Arch Allergy Immunol, 2026 · checked 2026-09-29
12. sf-lsc-r3-colby-1 · agency advice
    Pregnant women, the elderly, and those with weakened immune systems should not eat certain foods, including unpasteurized milk and unpasteurized milk products, any queso fresco-type cheeses, raw and smoked fish, raw sprouts, and certain other raw foods, which carry a high risk for L. monocytogenes.
    Listeria (Listeriosis), US Food and Drug Administration, Preventing Foodborne Illness at Home · checked 2026-10-08
13. colby-r2-10 · EU health claim decision
    POL-HC-6306 Dairy products (milk and cheese) Dairy foods (milk and cheese) promote dental health in children. -/- Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6306, snapshot 2026-09-21 · checked 2026-09-29
14. colby-r2-11 · EU health claim decision
    POL-HC-6305 Dairy products (milk, cheese and yoghurt) Three portions of dairy food everyday, as part of a balanced diet, may help promote a healthy body weight during childhood and adolescence. -/- Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6305, snapshot 2026-09-21 · checked 2026-09-29