Health Claim for High Oleic Oils Under Consideration by FDA

By Mark Messina, PhD, MS

Clinical evidence clearly indicates that replacing saturated fat with unsaturated fat (either polyunsaturated fat or monounsaturated fat) lowers circulating cholesterol levels and therefore should reduce risk of cardiovascular disease (CVD); a supposition that is supported by observational data. Not surprisingly, both commodity soybean oil, which is rich in polyunsaturated fat, and high oleic soybean oil (HOSO), which is rich in monounsaturated fat, have been shown to lower circulating cholesterol levels – which is recognized by U.S. Food and Drug Administration (FDA) as a surrogate endpoint for CVD and therefore capable of substantiating health claims.

The relationship between dietary fat intake and CVD has been investigated for more than 50 years beginning in earnest with the Seven Countries Study.¹ CVD is the leading global cause of mortality, accounting for over 17 million deaths per year. Given past recommendations, the American Heart Association recently strongly concluded that “lowering intake of saturated fat and replacing it with unsaturated fats, especially polyunsaturated fats, will lower the incidence of CVD.”² (See related article on Page 5.) Consistent with this recommendation is the FDA’s recent authorization of a strong qualified health claim for commodity (conventional) soybean oil, based on its ability to lower blood cholesterol levels. Language supporting this claim is much stronger than the language supporting the qualified claims for corn oil, olive oil, and canola oil.

FDA Language for Qualified Claims

Source: U.S. Food and Drug Administration

Commodity soybean oil, which dominates the edible oil market, is comprised of 50-55% linoleic acid, the essential omega-6 polyunsaturated fat, and about 20-25% monounsaturated fat (oleic acid).³ It also provides substantial amounts of the essential omega-3 fatty acid, alpha-linolenic acid.

Commodity soybean oil plays a huge role in the U.S. food supply accounting for approximately 7% of U.S. caloric intake.⁴ However, in response to demand from the food industry, two different HOSOs have recently been developed. These HOSOs are comprised of >70% oleic acid. A petition seeking a health claim for oils high in oleic acid (at least 10 grams per serving) is currently being evaluated by the FDA. 

Surveys indicate that consumers rate olive oil, which is rich in oleic acid, as the healthiest of oils even though, as noted, language supporting the qualified health claim for this oil is weaker than the claim for soybean oil. Furthermore, U.S. prospective epidemiologic data show that the replacement of saturated fat with polyunsaturated fat reduces risk of coronary heart disease (CHD) more than replacement with monounsaturated fat.⁵ More specifically, analysis of 84,628 women from the Nurses' Health Study and 42,908 men from the Health Professionals Follow-up Study, found that replacing 5% of energy from saturated fat with 5% of energy from polyunsaturated fat reduced risk of developing CHD by 25% whereas replacement with monounsaturated fat lowered risk by only 15%. 

Despite this evidence, the favorable consumer perception of olive oil is understandable considering the extensive amount of attention given to the health benefits associated with the Mediterranean diet over the past decade or so. Although monounsaturated fat is derived from multiple sources (e.g., HOSO, canola) olive oil is unique in that it contains compounds independent of its fatty acids (e.g., polyphenols) that potentially reduce CHD risk.⁶

Regardless of the source, substantial human data indicate that replacing saturated fat in the diet with oleic acid is cardioprotective. The petition submitted to the FDA seeking a health claim for high oleic oils suggested the following language be used for the claim:

"Daily consumption of edible oil with at least 10 grams of oleic acid per serving (one tablespoon) reduces the risk of coronary heart disease. To achieve this benefit, oleic acid containing oils with at least 10 grams of oleic acid per serving should replace a similar amount of saturated fat and not increase the total number of calories you eat in a day.”

The petition for the health claim is based on the hypocholesterolemic effect of oleic acid. Two clinical trials were cited as the primary support for the cholesterol-lowering effect and a third trial was considered important, but carried less weight.

In the first trial cited (a randomized, controlled, single-blind, crossover clinical study), 36 hypercholesterolemic adult men and women consumed a typical Western diet containing either high oleic rapeseed (canola) oil (73.7% oleic acid) or a flaxseed/high oleic canola oil blend.⁷ The diets derived 50% of their energy from carbohydrates, 15% from protein, and 35% from fats. Only the fat, and thus the fatty acid composition, was modulated between the control and intervention groups. Diets were consumed for 28 days followed by a 4-8 week washout period. Diets were prepared in the metabolic kitchen at the Richardson Centre Clinical Nutrition Research Unit at the University of Manitoba, where study participants consumed breakfast daily and were supplied cold-packed takeout lunches and dinners for consumption outside of the research unit.

As seen in Table 1, total and LDL-cholesterol values were significantly lower in the rapeseed-containing diets. Reduction in cholesterol in the blend diet occurred, despite containing similar amounts of monounsaturated fat as the Western diet; the former was much lower in saturated fat (7.5% vs 28.6%) and much higher in alpha linolenic acid (32.4% vs 0.8%).

Table 1. Lipid concentrations (mmol/l) at the end of each of the three experimental diets*

Source: Reference.⁷ Mean values within a row with unlike superscript letters significantly different between treatment groups (P<0.05).

The second study cited in the petition examined the effect of dietary fat saturation on cholesterol levels in 21 normolipidemic women (13 premenopausal and 8 postmenopausal) during three consecutive diet periods.⁸ During the first 4 weeks, participants consumed a diet high in saturated fat rich in palm oil and butter [19% saturated fatty acids (S), 14% monounsaturated fatty acids (M), and 3.5% polyunsaturated fatty acids (P)], followed by 6 weeks of a monounsaturated diet rich in olive oil (11% S, 22% M, and 3.6% P), and 6 weeks of a polyunsaturated diet rich in sunflower oil (10.7% S, 12.5% M, and 12.8% P). Approximately 36% of the calories on each of the diets was derived from fat. As can be seen from Table 2, compared with the diet rich in saturated fatty acids, both diets rich in unsaturated fatty acids lowered total and low-density lipoprotein cholesterol. Although not shown in Table 1, high-density lipoprotein cholesterol and apolipoprotein A-I were higher during the monounsaturated-rich period than in the polyunsaturated-rich (10.5% and 12.7% respectively, P < 0.001) and the saturated-rich periods (5.3% and 7.9% respectively, P < 0.05).

Table 2. Lipid concentrations (mmol/l) at the end of each of the three experimental diets*

Source: Reference.^{8 a}Significantly different from saturated fat diet

As noted above, a third trial was also cited in the petition but, because of some design weaknesses, was not relied upon as heavily to support the health claim.⁹ In this randomized, single-blind study, changes in serum lipid levels were assessed in 16 men consuming diets that provided 39% of calories as fat from either safflower oil or canola oil-based diets for 8 weeks after initially being stabilized for 3 weeks on a typical American (baseline) diet. Compared with baseline, LDL-cholesterol decreased from 3.78 to 3.03 mmol/l in response to the high polyunsaturated fat diet and from 3.64 to 3.21 mmol/l in response to the diet high in monounsaturated fat. The decreases were statistically significant in both cases. The high polyunsaturated diet contained 7% saturated fat, 9% monounsaturated fat, and 22% polyunsaturated fat, whereas the high monounsaturated fat diet contained 7% saturated, 22% monounsaturated and 11% polyunsaturated.

Conclusions

If the FDA approves the pending petition for a health claim for oils high in oleic acid, HOSO will qualify for a health claim. The claim will help to increase public awareness that oil produced from the soybean can meet the demand for foods high in polyunsaturated fat and monounsaturated fat. It bears emphasizing that the benefits of unsaturated fat are not necessarily limited to lowering LDL-cholesterol levels but may also include reducing insulin resistance¹⁰ and visceral fat,¹¹ and enhancing endothelial function¹² and cholesterol efflux capacity.¹³ Thus, there are multiple reasons for replacing dietary saturated fat with unsaturated fat.

References

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